Should I schedule continuous or daily backups?

My brother, Laurie, has requested a credit for inspiring this week’s blog by asking this question, so “thank you, Laurie, consider yourself credited”. What does the question mean?

Backup Drive on a Laptop

If you leave it connected, how often should you back up?

Actually, this is a different slant on a recent blog post called “Should you leave backup drives connected?

A lot of external hard drives now come complete with their own backup software. Unfortunately, they are never “plug and play”. They need to be configured according to your own preferences. We are talking of Windows computers, here. If you have a Mac then just use the inbuilt “Time Machine” option in System Preferences.

One of the choices to be made on a Windows PC is “how often do you want the backups to happen?” The usual options are:

  • Continuous – files are backed up as soon they are newly detected or whenever they are updated
  • Hourly (not always available as an option) – additions and the latest version of changed files from the last hour are all backed up at once
  • Daily – as above but only once per day
  • Weekly – as above but only once per week

Seagate External Drive in a Box

Seagate include backup software with this 1tb USB 3 external drive.

Let’s dismiss the “weekly” option to begin with. Why would you go to the trouble of buying a backup drive and then configuring it, only to leave your data exposed for anything up to a week? There is hardly any more cost or effort required to back up daily than weekly.

If you’ve got a new(ish) computer that’s very quiet, you may not like the external drive whirring up every few minutes or so. If you have it on continuous or hourly update the noise might irritate you.

Continuous update will also use up the drive space on your external drive faster, of course, than a daily backup, but if the drive is at least twice as big as the initial (full) backup then that’s unlikely to be a problem.

Another argument against continuous (or hourly) backups is that the process of backing up might slow down your computer for anything else you are doing at the time. This isn’t a problem with daily backups as you can schedule the backup to take place at a time when the computer is switched on but you are unlikely to be using it (during a mealtime, for instance). In practice, a new(ish) mid-specification or high-specification machine is unlikely to be bothered by backups going on, but an older machine might be. If you think your computer is already slow, don’t hamper it further with continuous or hourly backups.

If you tend to do a lot of work in one day on the same file or several files, you may prefer continuous or hourly update to prevent losing loads of actual work all done on one day. However, my own way of dealing with that (when putting together proposals for computer support clients, for instance) is to keep saving different versions of the file as I go along (using “save as” instead of “save” and giving each file a different version number as part of the name). I then delete the interim ones when I’ve finished. Yes, this does mean that all the versions are equally exposed to hard drive failure, but that’s a risk I will take in exchange for ease of use.

Backup Strategy Joke - version 2Something else you may need to consider is how your backup software deals with backing up your emails. If you use webmail it’s not a consideration, of course, as your data is all at the server end and not on your computer. If you’re using an email client (program) – and particularly if you are connecting via POP – then you will have large data files on your computer and, since these constantly change throughout the day, you could end up with your backup program spending all its time backing up the latest version of a “pst” file (for instance). Some backup programs get over this by only backing up such files a maximum of once per day. With other programs, your email backup might not happen at all anyway as some backup programs can not back up open files. So, you would only have a backup if you remembered to close your email for at least 90 minutes at a time (if performing continuous or hourly backups) or if you closed it some time before the scheduled backup time (if performing daily backup).

All computer backups are analogous to insurance policies in that the more you pay in premiums (or the more time and effort you put into backups) the better the cover (or the less data you are likely to lose).

If setting a daily schedule actually works most of the time (ie the computer is switched on and capable of doing the daily backup most of the time) then I would probably favour daily backups.

Whichever method you decide on, I would strongly recommend checking the contents of the backup drive a few times to make sure that what you think is being backed up actually is being backed up. In particular, check for email backups if you use an email client (program) to handle your email.

Finally, I think I’m right in saying that some backup programs can work while the computer is asleep. By all means test this out if you prefer to do daily backups, but do make sure that you check to see that the backup is actually happening.

Checking your backup files may be simply a case of viewing the contents of the backup drive in Windows Explorer (now called File Explorer), but if the backup program has created its own proprietory backup file type then you would need to check the backups using the backup software itself. I’m afraid there’s also another potential complication in that Windows may be hiding from your view the folders that contain your emails and/or their backups on the external drive. There’s no room to go into that today, but give me a call if it’s a problem.

You may not need a new laptop to increase your storage capacity

It might be my imagination, but I think that my computer support clients are keeping their computers longer than they used to. If that’s the case, then one critical factor that could nudge them into the direction of replacing it is that the disc space is running out.

It’s always been possible to replace a hard drive with a larger one, but it’s not a job for the faint-hearted. The main choices are:

  • Buy a new, larger, drive, and fit this in place of your previous drive. This entails physically replacing the drive, re-installing Windows and all your programs, and then copying your data from the older drive. This can get complicated if you don’t have a Windows installation disc or other master discs. I think that most of my own computer support clients would not wish to tackle this. The problem (for me, at least!) is that it probably wouldn’t be worth calling me in to do it as the job would take so long that the money would probably be better spent on a new computer.
  • Clone the old drive to a new, larger, drive and swap them round. “Cloning” is a process that is meant to copy absolutely everything from the old drive and place it on the new drive in such a way that the computer won’t notice the difference (except that you’ll have more space on the larger replacement drive). Great in theory but it requires special software and sometimes it just doesn’t work.

Hard Drive Caddy for Optical Drive Bay

Hard Drive Caddy for Optical Drive Bay

The alternative to replacing the hard drive with a larger one (by whatever means) is to add a second drive. This can probably be done more easily on a “desktop” style of computer than a laptop because there’s more space in the case and the “wiring” might be already present.

But what if you’ve got a laptop? I used to think that adding a second internal drive wasn’t an option on a laptop, but I was wrong…

I have just replaced the hard drive in my main laptop with a solid state drive and then I installed a fresh, clean copy of Windows and my programs. I thought I was going to be faced with the dilemma of what data and/or programs to leave off because you can’t get a quart in a pint pot. My old 1tb drive (1000gb) has twice the capacity of my new, fast-as-greased-lightning solid state drive. I was assuming that I could put some of it on the new drive but then I’d just have to access the rest by attaching the old drive as an external drive. This is a bit clunky. It’s OK if the external drive is just being connected occasionally, but not if it’s going to be a semi-permanent attachment.

Nevertheless I started browsing Amazon (as you do), looking for a nice “enclosure” into which to place my old drive, when I came across a HDD caddy for a laptop drive.

Hard Drive Enclosure for 2.5 inch Hard Drive

Hard Drive Enclosure for 2.5 inch Hard Drive

What you do is remove the CD/DVD drive from your laptop, screw your second drive into this “caddy”, and replace it in the laptop in place of the CD/DVD drive. As long as your laptop is no more than three or four years old then the caddy should connect to it OK. Your drive will also need to fit the caddy. As long as it’s a new drive or not more than about five years old then it will also be a “SATA” drive so there will be no problem.

So, I ordered one of these instead of buying an external drive enclosure. Even taking it very carefully, it took me no more than about 20 minutes to fit my old drive as a second drive. No software to install or configure. Windows immediately recognised the second drive and gave me access to everything on it. No messing. The job’s a good ‘un.

External DVD Enclosure

External DVD Enclosure

Of course, this solution means that you will no longer have a CD/DVD drive, but you could buy an external CD/DVD drive for about £36. This link is to a Samsung external DVD drive offered by Amazon. Alternatively, if you’re enjoying messing around with a screwdriver, you can buy an enclosure into which to place the CD/DVD drive you took out of the laptop. This will then leave you with an external CD/DVD drive. It probably won’t be much of a problem having your DVD drive as an external one as we’re using these drives less and less and many laptops (particularly those described as “ultra” laptops) don’t even start off with a CD/DVD drive.

Just for clarification, in my own case I removed my original hard drive and it became my second drive (in the CD/DVD caddy) when the new solid state drive became my main drive. Unless you wanted (as I did) to start off a “clean” installation of Windows, you can leave your original drive where it is and just place a new hard drive in the CD/DVD caddy. This is a very quick and easy way to increase your internal storage capacity hugely at a stroke.

This solution works for machines that have a DVD drive on which the tray pops out when you press a button. I haven’t looked into whether it would work for the Apple-style of DVD drive where you just slide your DVD or CD into a slot.

How do I get rid of a computer but keep my private data private?

This is a simple question that I’m often asked by my computer support clients. Pity the answer isn’t as simple. In fact, it can be complicated – technically and/or financially.

If the drive is in situ in a complete computer and you wish to dispose of it as a working machine then you have to clean the private stuff off it by deleting it and then ensuring that the deleted data can not then be undeleted. I will be covering the principles of this in next week’s blog.

If the drive is already out of the machine and/or if the main intention is safe and secure disposal of the computer (without expecting the computer to continue to function) then it may be simplest just to keep the drive (as this is the only part of the computer that stores any of your private information) and dispose of the the rest of the machine without worrying about data security.

This strategy also has the advantage that the retained drive can be viewed as a backup of your data at the time you disposed of the machine. In theory, you should be able to read any data on the drive, even though you no longer have the computer it came from. In practice, I have found that hard drives that are not used for a length of time can fail to “spin up” when you try to read them – see this blog on Long Term Data Retention.

2.5 inch drive enclosure

2.5 inch drive enclosure – you can’t tell from the outside whether it is SATA or IDE (or both)

To try to read a drive that has been separated from its computer, you just need an external drive enclosure from somewhere like PC World, Maplin, or Amazon. This is a box into which the drive fits and which includes the electronics to allow the drive (in its new box) to be externally connected to another computer via a USB cable. In fact, all old drives can be fitted into enclosures this way and used, for instance, as backup drives. If possible, take the drive with you when going to buy such an enclosure as there are two questions that have to be answered correctly if you are to get the right enclosure:

  • Is this a 2.5 inch drive or a 3.5 inch drive? (in practice, laptop drives are 2.5 inch and desktop drives 3.5 inch)
  • Is it a SATA drive or an IDE drive? (if the computer is newer than about four years it’s likely to be SATA)

3 1/2 inch drive enclosure

3.5 inch drive enclosure – note that 3.5 inch enclosures have their own power supply

In practice, keeping old drives to use as backup drives in this way is not as useful as it used to be as the enclosures cost about £15 and the drive (since it is likely to be 2-5 years old) is probably quite small by today’s standards and might also be getting to the age at which the chances of it failing are starting to increase rapidly. If your main priority is getting a backup drive then it would probably be better to start from scratch and buy a new external drive for £45-£80. See this blog on External Backup Drives.

The conclusion from all this is that it’s worth retaining a drive from an old computer as this is a simple and secure method of (non)disposal. You also know that there’s a chance of reading it at a future date if you need to get some data off it.

The problem for a “normal” user is “how do you get the drive out of the computer”?

3.5 inch SATA drive

3.5 inch SATA drive

If it’s a desktop computer then there will be screws on the case of the main system unit that retain one or both of the side covers. After removing the cover(s), just look for a metal rectangular box similar to that captioned here as “3.5 inch SATA drive”. The precise method of removal varies between models of computer and varies between being “simple” to remove and “well nigh impossible: how on earth did they put this thing together?” The good news, of course, is that you’re probably not bothered about breaking anything as you are probably not passing this computer on to anyone as a potentially working machine.

2.5 inch IDE drive

2.5 inch IDE drive

If it’s a laptop computer then you are hoping to find one, two, or four screws on the bottom of the laptop that either retain a plate (the removal of which will reveal the hard drive), or which retain the drive itself (the removal of which allows the drive to be slid out from either the left or right edge of the laptop).

2.5 inch SATA drive

2.5 inch SATA drive – it is the connectors at the edge that differentiate it from an IDE drive

If you are unlucky, there are either no such screws or you can’t identify them. In that case, you will need to remove pretty well all of the many screws on the underside of the laptop in the hope that you can get the case apart and then remove the drive (which will be a 2.5 inch drive as shown). I strongly advise against pulling a laptop computer apart if you are hoping to keep the machine alive for another owner.

Next week I will look at the options for keeping your data safe when disposing of a computer with the drive left in situ.

Can you assume that your computer data will be safe and accessible for as long as you need it to be?

How should we store our important computerised data so as to be reasonably sure that it will be available to us for us long as we need it? Is there any electronic format that we are sure will do the job? I’m not sure that there is an obvious answer to this question.

Part of the personal computing revolution
at the beginning of the 1980’s included the ability to store programs and data on magnetic media in the form of the floppy disc. This was a circular disc that rotated inside a protective, semi-flexible (ie “floppy”), sleeve. I think there were discs measuring about 8 inches across at one time. When I got into the field in 1983 the current size was a 5 1/4 inch disc. These contained about 1/3mb of data.

I’m fairly sure that I’ve still got a drive to read these discs somewhere, but I’ve got no idea whether that drive is still compatible with modern computers. If I couldn’t read the disc myself then I would do some googling in the hope of finding a company specialised in reading old media formats. This would probably be expensive and I don’t know what the chances are that the discs themselves would still be readable – even if the “reader” were available and working.

So, if I’d written the greatest novel of the 20th century, stored it on 5 1/4 inch discs, and then forgotten about it, I may or may not be able to read the disc (and may or may not have a program capable of interpreting the data even if the disc itself were readable, but that’s a different story).

Scrunched Floppies

A client asked me to render these old 3 1/2 inch floppies unreadable by pulling out the discs and scrunching them up

The media that took over from the 5 1/4 inch floppy was the 3.5 inch version. This time the case was rigid and the capacity had increased about fourfold. If you have a computer that’s older than about five years then it may have a drive that can read/write these discs but the chances are that if you still actually use it then it will probably be because you have an old accounts package that wants to do data backups onto floppies (accounts data doesn’t take up much room, so it is still quite feasible to do this).

If you put the greatest novel of the 20th century onto 3.5 inch discs then you wouldn’t have a problem accessing it as you can still buy external 3.5 inch floppy drives that connect via a familiar USB interface. If the discs have been kept in a reasonable environment then you can probably still read them. You couldn’t use floppies for most of today’s data storage requirements as they just aren’t big enough.

You might expect that any storage discs newer than floppies would be straightforward as these would be CDs or DVDs. Again, if your computer doesn’t have a drive to read/write these then you could attach an external one.

Disintegrating CDs

You can see the coating starting to come off at the edge of these CDs

No problem there, then, but it’s not just the survivability of the drive to read the media that we need to worry about. It’s also the media itself. I recently dug out an oldish music CD that was disintegrating from the edge (see the illustration). OK, it wasn’t a proprietory disc (so the legality of the copy is somewhat challenged), but my point is that I don’t think the disc is more than about 10 years old. Another short while and the disintegration will have worked its way onto the data area and the disc will be useless. Is this going to happen to all CDs? Maybe I was just unlucky. Maybe the CD was cheap. The point is that the disc could have contained important stuff and that stuff would be at risk.

Where else can you put your data for long term safety?
Hard drives seem like a good bet at first sight. However, I recently dug out a pile of redundant hard drives that I thought were in perfect working order and two out of four refused to start up. Is this typical of what happens to a drive if it isn’t used? I don’t know, but I certainly won’t be trusting a unique copy of anything important to a single drive.

What about pen drives (aka thumb drives, USB drives, or (erroneously) “memory sticks”)? It’s possible that these fare better in the long term. After all, there are no moving parts. You can now buy these with capacities of 64gb. That’s usually plenty big enough to store all your important text data, if not photographs and music.

Pile of Hard Drives

Old hard drives may not “spin up” if not used for a long time

But maybe the safest bet is to commit your data to an online cloud storage service. I would still feel a bit queasy about putting all my eggs in one cloud basket (as it were), so would replicate the storage in two different services (eg Microsoft’s SkyDrive and Apple’s iCloud). It may not yet be practical to do this if you have lots of data as online storage costs money for large storage amounts. Nevertheless, this situation is bound to improve as storage continues to become cheaper and data transfer speeds continue to rise.

So, there doesn’t seem to be a single, obvious solution at the moment and I’ve got a lot of sympathy for all those people who only really feel safe with their data storage if they’ve got a hard copy on good old paper (which, itself, disintegrates in time of course). For my own stuff, I think I’ll continue spreading my backups around between hard drives, CDs, DVDs, pen drives, and keeping some of my old stuff handy in Dropbox etc.

And I always, always, have at least two archive copies of anything important.

“Should I buy an external backup drive” is one of the most common questions I am asked by my computer support clients

My answer is usually “yes”, because the question implies that the client is not backing up anything at the moment. The next question is, of course, “what should I buy?”

The main considerations are these:

Form Factor

Western Digital 3.5 inch external drive

Western Digital 3.5 inch external drive

External drives are either 2.5 inch or 3.5 inch. This is a measure of the width of the drive itself (not the housing in which it is contained). Functionally, the two sizes are the same. The physical size of the entire unit in its housing is, however, quite different. If you think you might want to carry the drive about with you then the smaller size would be more suitable. Apart from physical size, the other main difference is that 2.5 inch drives are usually powered via the USB connection, whereas 3.5 inch drives have their own power supply. This might make them slightly more reliable, but it does, of course, mean that you need to find yet another power socket within reach.

At the moment, capacity ranges from about 340gb to 3tb. A “tb” is a “terabyte” – ie 1000gb (gigabytes). So, the 340gb is approximately 1/9 the size of the 3tb. You might like to look at the comments I made on hard drives in this post on buying laptops as they also apply to buying an external drive for backup purposes.


USB3 port

A USB3 port, distinguishable by being blue inside

Connection to the computer is via either a USB2 or USB3 port. Drives with USB3 connections transfer data much faster then USB2 connections provided that the computer at the other end also has USB3. If it doesn’t have USB3 then transfer happens at the lower USB2 speed. I would definitely recommend buying a drive with USB3 even if your current computer does not have USB3 – your next computer will have. You can, by the way, always tell a USB3 connection as it is blue inside (as opposed to the black of a USB2 connection).

Rotation Speed

Different discs rotate at different speeds. 5400 rpm is a typical speed. Faster spin speeds result in faster data transfer rates but there are other factors that affect how fast a drive performs, so the “rpm” figure is not necessarily all that significant.

Backup Software

These notes about backup software are for Windows PCs only. Although the drives themselves are compatible with both Macs and PCs, backup strategy is different. If you own a Mac then you would undoubtedly use the external drive with the Mac’s inbuilt “Time Machine” software. This is much better and simpler than any backup software ether built into Windows or provided on an external drive.

However, if your are a PC owner it may be important for you to make sure that the drive you buy has its own inbuilt backup/restore software. This is usually fairly easy to set up to perform automatic incremental backups of data files in standard locations. This may need a bit of explanation:

  • “automatic” – the backups are automatically created according to a user-defined schedule.
  • “incremental backups” – files are backed up (according to the schedule) after they are first created (or, more precisely, when they are first saved), and also every time they are updated (ie when they are saved again).
  • “standard locations” – some software will only back up data files that are located in the “Documents” or “My Documents” folders (and their sub-folders). In other words, the software may or may not be configurable to back up files saved in other locations.

When it comes to backups, the devil tends to be in the detail. The principle is fairly easy – backups are copies of files that you create as potential replacements for lost, deleted, or damaged files. However, there are many types of backups, many different scheduling possibilities, many sorts of backup media, many different storage strategies and so on. My experience of many years with my computer support clients is that it is better to have a simple backup strategy that you actually carry out, than a complicated one that you don’t. The simple solutions provided with external drives are usually fairly quick to set up and are undoubtedly better than no backup at all provided that you normally save your data files in the default areas within “My Documents”.

Please note that this blog post is a general guide only. I am not promising that any specific software performs any specific backup task. You are urged to check the results of taking backups so that you can be fairly confident that the procedure works.


Seagate 2.5 inch external drive

Seagate 2.5 inch external drive

Larger drives tend to offer better value in terms of price per gigabyte, but it could be false economy to buy a 3tb drive if you will never use it. 500gb drives start at about £50.

As a very rough guide, if you rarely or never store movie/video files, music files, or very large numbers of photos in specialised formats (such as RAW or TIFF) then a 500gb is probably going to be plenty large enough. If you take a lot of photos, or have an increasing music and/or video collection, then maybe a larger drive will be better.

So, in conclusion, if you are thinking of getting an external drive for backups purposes, then do it! I have seen for myself just how upsetting and disruptive it can be to lose data completely. Any backup is better than no backup.

Years ago we used to have parallel ports, serial ports, scsi ports and goodness knows what else. Things are a lot cleaner and more straightforward now that most things connect to computers via a “USB port”. USB stands for “Universal Serial Bus“, strongly suggesting that this is a method for connecting all kinds of things via the same socket (or “port” as computer people call them).

Nowadays, we take USB ports and connections for granted, but there are a few things that it’s worth pointing out for the benefit of normal human beings (eg my own computer clients) who need to use them every day but don’t normally take any notice of them.


USB3 Ports

USB 3 ports are blue inside

USB3 is the latest “incarnation” of USB connections. The main improvement that we will notice is that USB3 is much faster. See this Wikipaedia article for more details. USB3 hasn’t yet completely replaced USB2 ports on new computers, but where they are present there seem to be one or two of them on a computer that also has one or two USB2 ports. As always with these things, I think we can get what my chemistry teacher used to call “delusions of accuracy” if we measure these things to the nth degree. However, I can tell you that transferring significant amounts of data (say 5gb or 10gb) to an external hard drive is definitely a lot faster with USB3 than USB2. Note, though, that it’s not enough to have a USB3 port on the computer: the destination (eg an external drive) also has to support it for the speed to be improved. It’s easy to tell which ports are USB3 as the inside of the port is blue (compared with black for USB2) – see photograph. USB3 ports are “backwardly compatible” so any USB2 device can be plugged into a USB3 port (and this will work at USB2 speed).

USB Sleep and Charge

Some computers now come with one or more USB ports that keep the power on when the computer is asleep or switched off. This means you can plug in a smartphone – or similar device that re-charges via a USB port – without having to keep the machine switched on or even plugged in (if it’s a laptop with its own battery connected).

Cables with Double Connectors

USB Cable With Double ConnectorHave you ever bought a USB-connected device that came with a cable that has two connectors at one end (see illustration)? If so, you may be wondering what the “spare” connection is for. Well, it’s just to ensure that the device is getting enough power from the computer it is connected to. Simply connect both of the “double ends” to ports on the computer. If you only connect one of the pair and the device doesn’t work then try the other. If it still doesn’t work then you definitely need both ends to be connected to get enough power to run the device. That can be a problem on laptops with limited USB ports. My old Samsung Q35 laptop only had 2 usb ports and they were on opposite sides of the case so the only way to connect power-hungry USB devices was to attach a USB extension cable to one port so that both ends of the USB cable were within reach. A bit messy and inconvenient.

Problems with USB Connections

The word “universal” suggests that you would expect a USB connection to work in any USB port. Generally speaking that’s true, but if you find that a USB-connected device doesn’t work it is definitely worth trying it in a different port. The port that didn’t appear to work for the first device may work with another device connected to it. I think this is all to do with the amount of power available to run the device and that some ports may be able to deliver more power than others (due to their position on the motherboard?) I’m not completely sure about the technicalities of this but I’m absolutely sure that it’s worth trying to swap them around. If you’ve got a lot of USB ports with lots of devices and you need to dis-connect them all (to pull the computer out from under a desk, for instance) then it’s well worth noting which device was connected to which USB port so that you can be sure of putting them back in the tried and tested configuration. When working on my own computer clients’ machines, I will sometimes take photographs of the connections before pulling things apart.

USB Ports Too Close Together

USB ports are often sited very close to each. This is usually OK if the connectors are of the standard size but some devices – such as wireless USB receivers and so-called “dongles” – are just too fat to place next to connectors in adjacent ports. The easiest solution in such situations is to buy one or more short USB extension cables and connect the fat device via the extension cable. The cheapest place to get things like this is at a computer fair but I wouldn’t expect normal people to frequent such places so you’ll have to bite the bullet and pay Maplin or PC World prices (or cadge one from me when I’m with you providing computer support or advice).

USB Hubs

4 port USB hub

4 port USB hub

These devices plug into a USB port and then allow you to plug two, four, or even more USB devices into them. In most cases they work fine, but try to avoid connecting external hard drives or CD/DVD drives into a hub unless the hub has its own power supply. This is because the computer may not be able to deliver enough power to the device if it’s going through a hub (that may also have other devices taking power from the same USB port). USB devices that are definitely suitable for connection via a hub include mice, keyboards, and cameras.

Hard drive with file iconsWhat are the factors that make file size relevant?

  • The first that comes to mind is the size of an email attachment. As discussed in a previous blog on emailing large attachments it’s possible that an attachment of greater than 5mb will not get through.
  • CD – if you are copying (“burning”) files to a CD then you have about 730MB available (less if it’s a re-writable CDRW). Depending on the software that you are using to do the copying it is possible that you may be able spread the copying over several CDs. You really wouldn’t want to be doing too much of that. If you have so much data that it needs to span several CDs then you’d probably be better off copying to a different medium (DVDs or USB pen drives, probably).
  • The size of a USB pen drive. These are also called “thumb drives”, “flash drives” or “memory sticks”, but the pedant in me insists on pointing out that “memory stick” is a misnomer since it is the name of a specific type of Sony device. An old pen drive may have a capacity of 64mb or even lower. These days the most common sizes are 2, 4, 8, and 16gb. The best value in terms of “£ per GB” is probably 8gb at the moment. My advice to my computer support clients is that if you are only going to take backups of your most important data files, and if this is going to happen on an ad hoc basis, then copying onto a pen drive (say 4gb or 8gb) is going to be your best bet.
  • DVD – if you are copying files to a DVD then you have about 4.3GB available. There are also “dual layer” DVDs that double the capacity but they need the right hardware and the right DVDs. I’ve found them unreadable sometimes (even with the right hardware) so I don’t use them.
  • “Cloud” storage – if you are saving data to an online server (either for backups or to make data available to different computers) then there will be specific limits that depend on your package. For instance, Dropbox will give you 2gb free storage but you can purchase much bigger amounts. If you want a free Dropbox account, by the way, please follow this link to sign up as you will get an extra 0.25gb free and they will also give me an extra 0.25gb for referring you! The other consideration for online storage is that it can take an appreciable length of time to actually upload large amounts of data to online storage and it’s possible that the performance of your computer might be affected while the uploading is going on. This could become irritating if it happens often and for long periods at a time.
  • Hard Drive storage (both internal and external). If you have an old computer your hard drive may be as small as 40gb or 80gb. It’s hard to buy a drive smaller than 160gb nowadays and you can go all the way up to 2 terabytes (where a terabyte is 1000 or 1024 GB). If you are using Windows XP then your Windows and “system files” and program files could be taking as little as 10gb between them. A Vista or Windows 7 machine could easily be taking 50gb for Windows and Program Files. In either case, take the requirement of Windows and Program Files from the disc size and you are left with the space available for your data files. Do take an unhealthily large pinch of salt with these figures, though, as there are other things that take up disc space (such as the virtual memory “paging file” that could be anything from 1gb to 12gb).

Please only think of rough estimates when doing calculations of file sizes, what will fit where, and so on. There are complicating factors not dealt with here. For example, the amount of space on a drive that a single file occupies is always going to be higher than the actual file size. This is just an inevitable result of the way the operating system allocates space and reads/writes files in “chunks” other than the actual file size. We needn’t be bothered about this as long as we’re always thinking in terms of approximate sizes and spaces.

So, all of this can get a bit complicated – not to say nerdy – and we should be wary of getting “delusions of accuracy” when trying to assess file sizes and space requirements. So why bother? Let’s take some extreme cases:

  • It wouldn’t be sensible to try and store a backup of your movie collection to an online account – especially if you are paying for the storage.
  • There’s no need to spend £60-£70 on an external drive if you just want to back up 1000 spreadsheets and word processing files of 1mb each. This could become an increasingly important aspect if the rise in hard drive prices (caused by the floods in Thailand) persists.

If you have no grasp of relative file sizes then it might – on the face of it – seem wise to store just 20 files (movies) online and 1000 spreadsheets on an external hard drive. In actual fact, ignoring for now any security implications, it could well be that the opposite would be the case – put the spreadsheets online and the movies on a spare external hard drive.

So, next week we’ll finally get to the details of how we can check the size of files and the space available on different media to accommodate them.

How big are files? Last week we looked at hard drives in terms of the different definitions of their size. Let’s have a look this week at the range of different sizes of files that will be stored on the drive.

File Icons - 1

The size of computer files can be important for a number of reasons:

  • The amount of space required to store them could be relevant. Will the file(s) fit onto the chosen medium – eg internal or external hard drive, CD/DVD, USB drive? An internal hard drive, by the way, is a sealed unit that stores data and which is more-or-less permanent in the computer. It can be removed fairly easily if necessary, but in normal circumstances it remains in the computer. When the computer is started it normally looks to the internal hard drive for the programming (eg Windows or Mac operating system) to get it started. An external drive is exactly the same type of drive but it is housed in a separate box that includes the electronics to allow it to be connected to the computer by a USB cable. An external drive can be attached or removed very easily.
  • The time it takes to copy or transfer the file(s) to any of the locations mentioned above might be relevant – eg if you ask me, during the course of computer support work that I am doing for you, to copy a dozen 4gb files from one hard drive to another then that could take an hour or more. You might decide to do that copying yourself.
  • It may be that the system that will handle the files may not be able to cope – eg email attachments might be too big to be delivered. See my previous blog on emailing large attachments.
  • There may be direct costs associated with moving/transferring files – eg the downloading costs of using a mobile phone data account, or caps on the amount of data that can be downloaded per month on a broadband account.

For all the above reasons it makes sense to have some grasp of the relative size of files so that you know whether size is an issue in any particular situation.

File Icons - 4

Let’s start by seeing how file sizes are measured:

  • 1 byte is the room taken by a single character (a letter or a digit, for instance)
  • 1KB (kilobyte) can either mean 1000 bytes or 1024 bytes
  • 1MB (megabyte) can either mean 1,000,000 bytes or 1024 X 1024 = 1,048,576 bytes
  • 1GB (gigabyte) can mean either 1,000,000,000 bytes or 1024 X 1024 X 1024 = 1073741824 bytes

This “dual definition” was touched on in last week’s blog. For a fuller explanation see

So, if you see a file size expressed in “KB” and the figure is less than 1000 (eg “580KB”) then you know that that file is “about half a megabyte”. Similarly, a file that is 256mb is “a quarter of a gigabyte”.

File Icons - 2

Size and importance are not necessarily related

As things have developed over the years, I have been struck by how much variation there is now between small files and large files. The largest files are now many many times bigger than the smallest files but that doesn’t mean they are any more important. A single page Word document of much less than 1mb (your CV, for instance) is probably more important than a movie that is 4000 times as big.

Also, it’s not necessarily true that large files are less convenient than small ones. A folder containing 70mb of music files (a typical size of a complete album digitised at a reasonably high quality) doesn’t change and doesn’t need backing up more than once at most. In contrast to that, you might choose to store all your usernames and passwords in a single (password-protected) spreadsheet file. That spreadsheet file could be less than 1mb but it would be absolutely crucial to take regular backups of such a file onto media other than the hard drive it normally sits on. This file would also be a prime candidate for storing online. So, you would need to be paying far more attention to the small file than the much larger music files.

File Icons - 3
What are some typical sizes of some popular file types?

  • Word document – anything from 5kb or less, to 1mb upwards
  • Spreadsheet – anything from 5kb or less, to 1mb upwards
  • A music track – probably about 1mb per minute of music
  • A jpg from a 3 megapixel camera at 90% quality – 504kb
  • A jpg from a 5 megapixel camera at 90% quality – 692kb
  • Video – hugely variable depending on the quality, the compression, the pixels per frame, etc. In any event, much bigger than other “data” files
  • Program files – hugely variable. It’s quite common now for a newly installed program to take up 100-200mb. Equally, you may have an indispensible little program of 5mb or less.

Next week we will look at some of the implications of dealing with files of different sizes and how we assess the size of files and the space to accommodate them.

Let’s suppose that you’ve finally decided to buy an external drive to back up at least some of your important files. Maybe you’re doing this just because you know it’s a good idea or maybe you are a computer support client of mine and you’re tired of me dropping very heavy hints about backups.

Windows Explorer Drive Capacity

How Windows Displays the Drive Capacity

I’m going to use a 160gb drive as my example for the rest of this blog. So, you connect the new drive to your computer, you open Windows Explorer to see what it makes of it and, lo and behold, it looks as if you’ve been sold a pup. Windows tells you that this is not a 160gb drive but a 149gb drive and although it’s brand new there’s less space available than the size of the drive. The difference between the 149gb (the capacity reported by Windows) and the 160gb (the capacity that the nice people in PC World sold you) is almost 7% of the total and that’s enough for a grumpy old man like me to feel cheated.

Actually, there are a number of things going on here. The most important is that the drive manufacturer and Windows are not agreeing on what constitutes a “gb” (gigabyte).

These days, 1gb = 1000,000,000 bytes (or 1000 megabytes). This is the designation that drive manufacturers use when labelling and selling their products. So, a 160gb hard drive means 160,000,000,000 bytes.

1gb used to be thought of as something different. This was derived from the fact that 1kb was not 1000 bytes but 2x2x2x2x2x2x2x2x2x2 bytes – ie 1024bytes. Calculating it this way, 1gb is actually 1,073,741,824 bytes. Strictly speaking, this unit is now called a gibibyte (GiB) but I don’t think I’ve ever heard anyone use that word.

So, I can multiply the 149gb that Windows thinks it has  X 1.073741824 bytes and get back to the 160gb which PC World claimed to have sold me.

Notice that Windows is reporting only 148gb of the 149gb as being available. There’s nothing I can do about that. It’s just pinched some space for its own use.

Seagate GoFlex 2.5 inch Drive

A Seagate GoFlex 2.5 inch Drive

Actually, your own brand new drive may be showing less space available for another reason. The drive may include free backup software. Defintely worth looking out for if you want a reasonably straightforward backup solution.

Does all this talk of space available on your new drive actually matter? Not really – unless you are paranoid or grumpy and think that the drive manufacturers are trying to cheat you.

So why am I telling you this? Mainly because you may have noticed the anomaly and wondered what was going on. I’m also taking advantage of the opportunity to emphasize that one of the best bits of computer advice I can give is that it’s a very good idea to have backups of at least your most important data files. Over the 27 years I have been providing computer support I have seen several instances of people losing their data because of something like a hard drive failure or virus attack. It can be very upsetting, and potentially serious if your livelihood is involved.

Another reason why we needn’t try to be too pedantic in working out how much space we’ve got available on the new drive is that we always need to leave a fair chunk of it unused. We need to allow a minimum free space of about 15% “wiggle room” if we are going to be regularly reading and re-writing the files on the drive. If any drive gets filled beyond about 85% capacity then the performance starts to degrade as the operating system struggles to effficiently store the data and read/write it from/to the drive. So, it’s always best to buy a drive that’s larger than your apparent needs.

Finally, the main reason that it doesn’t really matter too much about accurately measuring capacity against your precise needs is that the capacity of external drives is going up much faster than our need for all that space. It’s hard to buy a drive of smaller than 340gb nowadays and the best value in terms of “£ per gb” is probably a 500gb drive. The only thing that’s likely to use up that kind of capacity is a large movie collection. A large photo collection and a large music collection added together with all of your normal data files are unlikely to be a problem.

I know I’m always banging on about backups but there’s another reason why it may be a good time to act – external hard drive prices (in fact, all hard drive prices) may go up in the coming months. Floods in Thailand have wiped out a significant percentage of the manufacturing capacity and this could have a serious impact on prices.


Notice the rather ominous “1” in the title. This is a subject that will take more than one blog post. So, today let’s just think about what “backups” mean and what they don’t mean.

When I asked Google to define “backup” the first offering was

an accumulation caused by clogging or a stoppage; “a traffic backup on the main street”; “he discovered a backup in the toilet”

You’ll be pleased to learn that that’s not what we mean here. A better definition (offered by Wikipaedia) …

In information technology, a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. These additional copies are typically called “backups. …”

3.5 inch External Drive

3.5 inch External Drive

So at its simplest, a backup is a copy that can be used to replace an original if it is lost, deleted, damaged. This backup can be a copy of a single file (eg an important spreadsheet) or many files. At its simplest, a backup can reside on the same drive as the original. The problem is that if the entire drive fails then the backup is also lost. Having a backup on an external drive is a much better idea but that still wouldn’t avail you if all your computer stuff was stolen or in the event of flood or fire. The only way to be really sure that the backup will be there if you need it is to keep a backup in a location physically separated from the original. In practice, I’ve only ever very rarely managed to train my clients to such a degree!
What a Backup Isn’t

A backup is not usually a copy of any of the myriad files that make up the Windows (or Mac) operating system, nor a copy of the files that make up the programs on your computer (eg Microsoft Office, Photoshop). If we suspect that something has gone wrong with Windows or with a program file then the best thing to do usually is to un-install the program and re-install it. In other words, we don’t just copy back files that are in a backup, but set in motion the process of removing the program completely in the proper way and then putting it back from scratch from the original master CD/DVD or downloaded file. The reason for this is that program files have to be copied and set up so that they work in the specific situation and in concert with the other programs and operating system. Copying files is not enough to achieve this so we don’t back up program files.

What Data should be backed up?

Your own stuff. The documents and spreadsheets and pictures and videos and all the other stuff that is YOURS and that you would not want to lose.

There are also other types of file that are not quite so easily imaginable as data but which you wouldn’t want to lose – eg that huge list of bookmarks (also known as favorites (sic)) that you build up in your web browser (Internet Explorer, Firefox, Chrome, Safari, Opera or whichever browser you use). That list of websites is nothing more than that – a list – but I’ve seen a lot of clients looking very deflated when they realise they’ve lost it.

2.5 inch External Drive

2.5 inch External Drive

A hugely important part of backup data can be your email data. This is the email messages themselves, but can also be your contact information. If you only send, view, and receive your data through a web browser then your email data is not being stored on your own computer but on the computers of the service providers. This covers services such as Hotmail, Gmail, AOL mail, Yahoo, and others. This is known as webmail.


If, however, you access your email through a program on your computer (such as Windows Live Mail, Outlook, Outlook Express) then your email data is stored on your own computer. Your email provider may have a copy of your recent email history on their own computers (also known as mail servers) but it could be as little as the last seven days worth of data. Don’t rely on your mail servers as email data backups.

It’s also true that webmail can usually be accessed and downloaded with programs such as Outlook (as in the paragraph above), but we don’t need to split hairs about that now.

Having established an idea of what it is that we want to back up, let’s just finish this definition of what a backup is by considering some similar ideas:

An archive – in computer terms, an archive is just a backup but with one important difference. It is never over-written. Suppose you back up your data to an external hard drive. That drive is going to get full and you may wish to delete older backups to make room for newer ones. That means that you can’t always rely on your backups to tell you exactly what your accounts data (for instance) looked like on 23rd April 2009 (for instance). So, we often create archives in the knowledge that whatever happens we can see the data as it looked at a particular time in the past. Archives can be created in exactly the same way as a backup or by a different method. Often, for instance, archives are created on CDs or DVDs, whereas backups are made on external hard drives or USB pen drives (also known as thumb drives or memory sticks. A Memory Stick is actually a proprietary Sony device, so it is a misnomer to describe a generic USB pen drive as such).


An image – when we’re talking about backups an image is not a photograph. It’s a different meaning of the word and what it means is a complete, thorough, 100%, copy of EVERYTHING that is on your hard drive (or a sub-division of a hard drive such as a partition). An image can only be created using special software but it does seem to contradict what I said earlier about not being able to back up programs because a complete total image of your drive can actually be used to restore your computer to exactly what it looked like at the time the image was made – operating system, programs, data, the whole lot. But it’s not the panacea it sounds like because restoring an image could result in losing all the changes to the data that happened after the image was created.

Pen Drive

Pen Drive

A clone – similar to an image, a clone is the entire copying of one drive (or partition) to another similar drive so that it can be swapped with the original in case of disaster. The problem with images and clones is that they can take a while to create, you can only be completely certain they’ve worked by installing them, and they don’t change as data is added or changed.


That’s an introduction to backups. The next blog on this subject will look at the actual creating of backups in more detail.

One final word: I implore you to keep your master program discs all in one place and know where that place is. I would include in that any data backups and archives on “loose” media such as CDs or DVDs. So many times in the past I have been summoned by a distraught client with an apparent disaster on their hands who needs programs (and maybe data) to be re-installed but they can’t find their discs. This is already a fraught situation. It just makes it more stressful and more expensive if the client can’t find the discs. This doesn’t need to get complicated: just put everything in the same box and know where that box is.

© 2011-2019 David Leonard
Computer Support in London
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