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.

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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