File Sizes – 2

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.