Wednesday, 30 October 2013

Backup? What backup?

You all take regular backups of the critical data on your computers, don't you? And backups of your entire hard drive? But do they work? A wise sage once said "Your backups are only as good as your last restore", and that's probably right.

Over the years I've heard a whole host of horror stories about the subject, some pretty ancient. There was a colleague who visited a local office where there was a problem and who asked for the disk copies - and was given a folder containing photocopies of their data floppy disks! (This was obviously a few years back in the days of 5.25 inch floppies) - fair play to the office staff, no one had explained what was needed. Someone had just installed this amazing new bit of kit, shown them how to use it, and then said "Don't forget to copy the disks every day" - and as far as they were concerned copies were made on the photocopier.

And there was another colleague (same sort of era) who discovered that the backup floppies (real floppy disks this time) were kept safely where everyone could find them - clamped to the side of a filing cabinet with a large magnet!

And some years ago in the Green Party office when the computer died, and someone asked for the backup. No problem, sitting in the filing cabinet, taken the previous afternoon. All was well - luckily - as yesterday was the first backup they had made in six months!

And the office in a large insurance company in the early days of IBM PCs, before networks, where PCs were stand alone, and they had installed a tape cartridge unit and software on the PC for daily backups - which they did. And one day the engineer was looking at something and discovered the cartridge drive door was covered in cobwebs - they'd been backing up onto the same cartridge daily for the previous year - and those cartridges had a recommended lifespan of 20 uses.

Of course we're much more sensible these days - aren't we?

Personally I'm paranoid when it comes to data backups. I look at a long list of scenarios and try and have a setup that can cope with (almost) all of theml:

1) Hard disk crashes
2) File gets overwritten
3) Office burns down
4) Burglar nicks computers from office
5) Computer gets lost
6) Global warming floods Taliesin
7) Meteorite hits Taliesin

As a result, my backup strategy has several strands. I have software on my main computer that automatically runs schedules backups. The entire hard disk is backed up weekly, and my data directories daily. I keep daily backups for several months, and occasional ones before then. The backups are written to a Network Storage Device in another building.

From time to time I mount one of the backup files to check it works - I haven't dared to run a full restore though! But I'm thinking of upgrading the hard drive on my laptop, so that may be an opportunity to try it out...

This setup can cope with (1) - the full disk backup should allow a straightforward restore to a new drive using a restore boot CD.
(2) - the daily data file backups mean I can go back to the state of every individual file, every day for the last couple of months
(3) - the backups are in a different building
(4) - ditto - it's embarassing if your backup is on a bit of kit next to the computer which the burglar also nicks.
(5) - buy a new computer and restore from the full disk image
(6) - hopefully I'll have time to escape clutching critical kit
(7) - if I'm at home at the time, I'm past caring. If I'm not, there is a weakness which I'll be addressing soon. I have a couple of large, cheap USB hard drives, and I'm going to do a monthly manual copy of the entire system and store it at the house of a colleague who lives 20 miles away. We'll meet up monthly and swap copies - I'll be doing the same for him.

Overkill? Maybe, but I don't think so. For a business that relies on data stored in electronic form, the security of that data is absolutely essential. Lose the data and you lose the business.

And what about individuals and their home computers? And websites? I'll discuss those later...

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