How much space do your Windows folders occupy?

My earliest days of earning a crust in the world of computers were spent designing database systems (using a clever but tricky program called “Everyman” – I bet not many people remember that one). One of the first tasks in any design was to calculate the probable size of the data files. This was crucial as we only had two floppy drives to contain everything. Typically, one drive held the operating system (DOS) and the Everyman program files, and the other drive held the data. Floppy discs of that era had a capacity of about 1/3mb. If the data didn’t fit on a disc then the project may not be feasible. It wasn’t a case of every megabyte being important: every kilobyte was important.

Things have moved on a lot. A modern hard drive will usually hold at least 500gb. That is about 1.5 million times the size of a 5.25 inch floppy drive of the early 1980’s. If I were still designing database systems, I can’t imagine ever worrying about the size of the data files.

Despite this humungous increase in the amount of storage capacity we now have on our computers, there are still many reasons why we might want to assess the amount of space that some things use. For instance:

  • Can I get all I want onto a USB thumb drive?
  • Can I back up all my important data to my cloud account?
  • What size of drive would I need to back up all of my photos, music, or video collection?
  • Would last year’s holiday photos fit onto a single DVD? A single CD?

File Explorer

File Explorer in Windows displays the size of files, but not folders (rightmost column)

If you’ve only ever used a Mac you’ll probably be wondering what I’m on about as Mac’s behave as you’d expect (in this respect, at least!). When you open a Finder window on a Mac, the size of the folders is displayed next to the folder name in the same way that file sizes are displayed next to their name. Not so in Windows: folder sizes are not displayed. You can find the size of any individual folder by right-clicking on it and then left-clicking on “properties”, but this can get tedious and doesn’t give you a good overall picture of the situation.

Mac Finder Window

..whereas Finder on a Mac does display folder size

A way to get a better idea of the size of folders in Windows is to install a free utility called Treesize Free.

Once installed, you will now find that, if you right-click on a drive or a folder in File Explorer, there is now a new option on the “context menu” called TreeSize Free. Left-click on this option to open the utility.

TreeSize Fee - Access Denied Window

Figure 1. Just click on “Yes” to re-open as an administrator

When you open TreeSize, you may see a window pop up like the one in figure 1. This just indicates that there are system items in the folder (or drive) that you wish to examine and you won’t see these unless you open TreeSize as an administrator. Just click on the “Yes” button and the program will re-start, showing you all items.

TreeSize Free then lists each folder at the first level within the folder (or drive) that you right-clicked on. It lists them in order of size with the largest at the top. You can now get a very good idea of what’s been eating up your space and how viable it would be to move or copy folders. If there is a triangle next to a folder name then there are sub-folders within that folder. Click on the triangle to open the folder and see the sizes of its constituent folders and files.

TreeSize Free Folder Sizes

TreeSize Free shows the size of all folders in a folder or drive (in this case, my D: drive)

Many of the normal File Explorer options are available while you are looking at a TreeSize breakdown. So, for instance, you can cut, copy, and paste items to or from the TreeSize window.

Some of the other things you can do in TreeSize include:

  • Changing the area of your system that you are scanning by clicking the “scan” option on the menu at the top of the screen.
  • Measuring the percentage of the total area examined that is occupied by each folder.
  • Switching between measuring in gb, mb or even kb.
  • Switching between measuring the size of folders and the number of files within them.

I don’t know why Microsoft have never built something like TreeSize directly into Windows. As far as I’m concerned, it certainly counts as one of the top ten “utilities” available for Windows. If you right-click on any folder and find that TreeSize is already present on the context menu, then it probably means that I, or another computer support consultant, has already installed this really useful utility.

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.

How do you check how much space is available on your drive(s), and how do you check the size of the files themselves?

The usual way of checking on file sizes and space is by using “Windows Explorer”. This is nothing to do with “Internet Explorer” (the Microsoft browser program used to view web pages). Rather, it is a part of the Windows programming that comes to the fore when you double-click on the desktop item or “Start Menu” item called either “Computer” or “My Computer” (depending on the version of Windows you are using).

Here is a typical screenshot of what you will see when you invoke Windows Explorer using Windows 7. This view varies slightly between the different versions of Windows and you can choose to display the computer’s contents in different ways. The following is typical:

Windows Explorer (in Windows 7)

A typical view of Windows Explorer

There appear to be four different hard drives on this computer. There is, in fact, just one but I have split it into 4 “partitions” because that suits the way I work. It is quite common these days for computer manufacturers to supply their machines with the hard drive split into at least two partitions – usually called something like “System” and “Data”. It is easy to see both the total size of each “partition” and the free space available.

Notice also that Windows Explorer treats any CD/DVD drive in the same way as a hard drive. In the screenshot above there is no disc in my DVD drive (called a “BD-ROM drive” in this instance) so there is no figure for total space or free space.

Also, there is a USB pen drive (aka “memory stick”, “flash drive” etc) connected at the moment that has a total capacity of 3.72gb and free space of 1.42gb. Actually, this is a “4gb” drive. See this blog for an explanation as to why Windows thinks it’s only 3.72gb.

Viewing the Contents of a Drive

If we double-click on any of the rows describing a drive or disk then Windows Explorer will open up to show us the folders and files that are on that drive. Here is a screenshot of the contents of a particular folder somewhere on my hard drive:

Windows Explorer

Folders and Files

“Folders” are identified by the yellow icon. This is confirmed by looking under the “Type” heading and seeing that they are, indeed, described as “File Folders”. Folders are just places into which we can place files. We can easily create, move, rename, and delete folders. It makes sense to use folders to store files of a similar nature, according to our own wishes. So, we may have a folder called “Family photos”. We can then have folders inside folders (eg “Family Holidays”, “Family Events”) and then the individual files in the appropriate folder. Unfortunately, Windows does not automatically give us a figure for the size of the folder (ie the total amount of space occupied by the files in that folder). To find out how much space is taken up by the folder and its contents, we can “hover” the mouse over the folder name so that an “information box” pops up showing us the space taken by the folder:

Folder Size

Assessing the Folder Size

In the example above, I just placed my mouse cursor over the name “Seagate” and the box popped up telling me that that folder and its contents occupy 188mb of space. I could find more information about the folder by right-clicking on it and then left-clicking on the “Properties” option that comes up at the bottom of the menu.

It is easy to see the size of individual files using Windows Explorer. When I’m training clients I usually also show them how to find the size of groups of files but there isn’t really the space here today.

Windows has always been a bit limited in the information it gives about the size of folders – which are the ones hogging all the space on your drive, and other useful information of this kind. For many years there has been an excellent program available called “Treesize” that gives more information and a much better idea of what is going on with your disc space. There are different versions available – just click on the appropriate link below:

Treesize Free
Treesize Personal
Treesize Professional

Treesize integrates itself into Windows and is very easy to use. Once installed, you just right-click on the folder or filename and Treesize appears in the context menu that pops up. I recommend it to all my PC computer clients.

Dropbox logoOne final topic this week. I keep banging on about how good Dropbox is. Well, it definitely saved me some grief yesterday. I was doing some database development and something went wrong. I wanted to step back to a situation about one hour earlier but I had not taken a deliberate backup since I started the session about three hours earlier. So, I logged into my Dropbox account online. Dropbox appears to keep a backup copy of EVERY saved version of a file for the last month. There were about 200 different backup versions of the (very important) file I was working on. It was a very simple matter to just choose a version from about an hour earlier and restore that to the current version. Brilliant. And all these backup copies do not eat in to the allocation of data storage that Dropbox provides. In this case, my one single database file was bigger than 100mb so the 200-odd versions being kept online by Dropbox take up about 20gb on their own. However, only the current version counts against the storage allocation! Remember, if you want a free Dropbox account – with 2.25gb storage – register using this Dropbox link to gain that extra last 0.25gb free space.

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.


Is your hard drive working properly? Is it likely to fail? What would you do if it did?

A hard drive melting and going down a drainHard drive manufacturers used to rate the reliability of their drives in terms of a number of hours “MTBF” (mean time between failures). This was supposed to tell you how long you could reasonably expect a drive to last before a problem is likely, on average, to occur. It seems they don’t do this any more and I haven’t found out whether it’s because the figure was misleading or meaningless. Certainly, a study by Carnegie Mellon University found that users change their drives 15 times more often than the manufacturers would think they should.

I have seen various figures that suggest that, in practice, the reliability of drives starts to plummet at anywhere between five and seven years. All of this is irrelevant, really. The only important, irrefutable, fact is that drives DO fail. Given that fact, does it really make any difference whether there is a 1% chance or a 20% chance that your drive will fail in the next year? I’m by no means the only person to have known drives fail within their first year of life. The fact that such a drive would still be under warranty is not the point. The value is in the contents – your Windows installation, the programs, and the data. The best computer advice I can offer is that you assume that any drive can fail at any time.

So how do you know if a drive is failing?

Under normal circumstances, you may not know. However, there are two very definite signs that might be present – alone or together – that clearly indicate that something is going wrong:

  • An increasing number of errors, freezes, and program crashes may be caused by a failing drive. Such problems could be caused by disc drive read/write errors or by many others causes. It’s definitely worth heeding the warning and making sure your important data is backed up. You can then investigate further, knowing that you’ve protected the most valuable part of your computer system – your data.
  • A clicking noise coming from the drive. Act immediately. The drive could fail at any time. If there’s any data on the drive that you don’t want to lose, back it up NOW. If you’re not sure whether what you can hear is serious, visit this link and listen to some death rattles of failing drives. Be warned, though, that if your drive is starting to fail it could go at any time, so backing up data is a better use of its dying moments than having it clicking away in the background while you decide which of the sounds on the above link is the best match.

Monitoring a Healthy Drive

Most drives have something called S.M.A.R.T. technology built in so that appropriate software can monitor the health of your drive. The software that I use on my own machines for this purpose – and when providing computer support for clients – is called Active@ Hard Disk Monitor Free. This keeps a constant check on many of the parameters that indicate the health of your drive. It also has a temperature gauge to warn you if the drive is overheating. The only real limitation of the software is that it can only monitor internal hard drives. You can’t use it to monitor the health of, for instance, your USB-connected external backup drive. Nevertheless, I consider this a useful computer support tool that can give valuable warning of problems ahead.

Replacing a Hard Drive

If your drive has failed and Windows won’t start then you need to take a deep breath. There are specialist data recovery companies who may be able to get some or all of your data back but the cost could run into four figures. You may need or choose to buy a new drive and re-install everything from scratch, re-loading any data backups that you do have or that recovery specialists have been able to rescue. You may or may not feel confident to do this yourself: this is the type of computer support that people such as I, myself, offer. Don’t necessarily jump to the wrong conclusion, though. If you’ve just turned on your computer and Windows won’t load then there could be a reason other than hard drive failure, so there could be less drastic and less expensive options.

If your drive does need replacing, but is working reliably at the moment, then the best plan is probably to employ software such as Paragon Partition Manager to clone the entire drive. This is not entirely risk-free. I’ve known such software completely trash the contents of a hard drive partition by making a simple error when creating the clone. My own strategy when using it is to back up important data by a different means first, and then to use the cloning software. This is much, much, quicker than installing Windows, programs, and data from scratch. It has to be said, though, that this kind of task is not for the faint-hearted and may be beyond the technical knowledge of the average reader of this blog. Nevertheless, I hope it’s useful to point out the kind of options you may have if you suspect that your hard drive may be going on the fritz.

To sum up, the best single piece of advice I can give on this subject is this – don’t ignore the signs of a failing drive. You might be able to prevent a problem from becoming a disaster if you heed the warnings and act immediately.

Hard disc with cover removed

Hard disc with cover removed - don't ever remove the cover if you want the drive to work again!

Disposing of your old computer may not be as easy as might imagine.

You can not simply put it in a wheelie bin, destined for landfill. Computers contain several metals that will poison the ground. There are EU laws banning disposal in this way. Either take it to a local authority waste disposal site or contact your council to make a special collection.

Before disposing of it, though, it is prudent to ensure that no-one can get at the data on it. This applies whether the machine is going to cyber heaven or on to a new owner. Here’s a list of the broad options available to you:

If the computer is condemned

1) Remove the hard drive and keep it.


    1) If the the drive is still readable then this gives you a backup of your data. You will need some means – such as an external USB drive case – to connect this drive to your new computer if you wish to read it.

    2) There is no possibility of its contents falling into the wrong hands.


    1) It can be a bit of a chore geting the drive out of the case (particularly on older laptops).

    2) You do have to keep the drive somewhere (although, as my mother used to say, “it won’t eat any meat”)

2) Remove the hard drive and destroy it.

If you open up the case of a hard drive and deface the mirror-like surfaces with a screwdriver or sandpaper then you are almost certainly putting it beyond any readability or use. I agree that it may be technically possible for someone with all the right (very expensive and specialist) equipment to read fragements of the drive, but I would rather start worrying about the possibility of being hit by a meteor than worry about this happening.


    1) There is virtually no possibility of data falling into the wrong hands

    2) You don’t have to keep the drive


    1) You haven’t retained any backup of your old machine

    2) It can be a bit of a chore actually geting the drive out of the case (particularly on older laptops).

    3) It can be difficult to open up the case of a hard drive in order to deface it

3) Delete everything off the hard drive

You could use a software utility such as CCleaner to completely wipe the drive (including the operating system and all programs and data – whether deleted or not)


    1) Easier than removing the drive

    2) You can’t forget to delete specific data files


    1) You need to install and run the software and it can then take quite a long time to “scrub” the drive in this way (particularly if you set the software to make multiple “passes” over the drive).

If the computer is going to a new home

Removing the drive is a bit drastic. It is likely that the new owner won’t have the expertise to source a new drive, install it, and re-install the operating system and software. In fact, even if s/he does have the knowledge and resources it is very likely that it just won’t be worth doing. So, the aim is to pass on the computer so that it can be used with the minimum of fuss but without compromising your data. The options are:

1) Delete sensitive information

This includes your data files, your browser history, saved passwords etc. You may also need to un-install software that is licensed to you that you intend to install on your new machine.


    1) This is the least amount of work you need to do in order to protect your data.


    1) You may miss some data when deleting.

    2) The deleted data may be recoverable. If you have the slightest doubt about the integrity of the new owner or the destiny of the drive then the data that you think you have deleted could be vulnerable. This is because “deleting” data in the normal way does no such thing. What actually happens is that the operating system maintains a directory of the files that occupy the different parts of the drive. When you delete a file it simply changes the directory such that the space occupied by the (deleted) file is now eligible for re-use (ie the space can be over-written with a new file). The file itself is still present on the disc until the space is re-used and it can be “un-deleted” using special software tools.

Scrubbing brush and hard disc

2) Delete sensitive information and then “scrub” the drive

This consists of deleting the data as above, but then running special software that over-writes the space that may still be occupied by readable data. The software that I recommend for this is Piriform’s CCleaner.

Even this process can sometimes be “reversed” by highly specialised people and facilities. Frankly, I’m back to worrying about the meteor before worrying about this possibility. And if you are as paranoid as this, then you may also wish to consider the possibility of data still being present on the drive due to the drive head having shifted fractionally over time such that data you wrote onto the disc a long long time ago is still readable at the very edge of the tracks of data.


    1) Fairly easy to do and should satisfy the non-paranoid


    1) You may still fail to delete important data

    2) Won’t satisfy the paranoid. If you belong in this category,then I recommend that you read this article on data remanence

3) Delete everything off the hard drive

You could use a software utility such as CCleaner to completely wipe and scrub the drive (including the operating system and all programs and data).


    1) You can be sure that you didn’t leave anything behind that you would rather have deleted.


    1) You need to install and run the software and it can then take quite a long time to “scrub” the drive in this way (particularly if you set the software to make multiple “passes” over the drive).

    2) The new owner will need to re-install the operating system and software.

Conclusion: whether your old computer is at the end of its life or going to a new home you will almost certainly need to take steps to protect your confidential data prior to disposal.

© 2011-2019 David Leonard
Computer Support in London
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