Remember: backup is not archive

Imagine you’re sitting at your PC and suddenly realise that you’re running out of disk space.

You’ll need to delete some files, but don’t want to lose them forever. What should you do? Most people would say, “Back up your files!”

You think so, too? Well think again. Recently, one of my colleagues – who should have known better, I might add – did just that. He used a website that allows 2GB of free online backup, and for an astonishingly small fee will allow you to back up your entire hard disk onto its servers.

My colleague decided that this was the way to go. “You don’t want to use local CDs,” he explained, “because they’ll get destroyed in the fire if your main PC gets burned up!.”

So he went onto the internet and prepared to back up his hard disk. But two nasty surprises awaited him as he pressed ‘Go’ and sat back.

The first was the discovery that this was going to be one of those Scott of the Antarctic moments. “I may be some time,” said Captain Oates, as he walked out of the tent to his death. My friend should have done the arithmetic.

Today’s typical £500 PC will rarely have less than 80GB of disk storage, and it might even have 250GB or more. No doubt when my friend bought his machine he thought he’d never fill up a disk that big.

But after spending several months on allofmp3.com and downloading from his 8-megapixel camera, and saving clips from YouTube.com, and using his PC as a personal digital video recorder, he was on the brink.

Your ADSL line runs at about 512Kbits/sec upload speed – if you’re lucky. It’s more likely to be half that, or even less, if you’re on a budget service. Yes, you can download at 8Mbits/sec, maybe even 10Mbits/sec, but backup over the internet is uploading, not downloading.

Here’s the arithmetic. An upload speed of 256Kbits/sec means 32Kbytes/sec (1 byte = 8 bits, of course). That’s a megabyte (1,024Kbytes) every 32 seconds. How many megabytes in a gigabyte? Yes – you’re looking at (for a hard drive maker’s gigabyte of 1,000MB) 32,000 seconds per GB. So for 80GB, that’s 2,560,000 seconds. And 250GB is 8,000,000 seconds.

In minutes, the number is 133,333, which won’t allow you to watch the progress bar while the data is backed up and still get down for supper. In fact, the 2,222 hour-long transfer will see you starve: it’s actually 92.5 days.

My friend soon realised this and speedily cancelled the transfer. He went through the menu, selecting ‘Urgent’ and ‘Important’ files to back up. He selected only 5GB. Still, two days? “That can’t be right!” he said. “I downloaded 5GB of Windows Vista in just an afternoon! Oh… right… that was downloading.”

Two days later, it still wasn’t done. Some of his fellow internet users had been uploading things, too; file sharing, Bit Torrent – that sort of thing. Contention on the line. But all things come to those who wait – and by the following weekend, it was done.

With a sigh of relief, he deleted the files, freeing up some space. He also deleted a few other files, less important ones that didn’t need to be backed up, and got about his business. A month later, he realised he needed one of those deleted files after all and went to the internet backup site. He searched and searched for the files, but they were gone.

A very little investigation produced the following response from the internet backup operator: “Yes, that’s the way we work. We keep backups of files on your disk. If you delete them, then you have a week to change your mind, and then we delete them too.”

My colleague was absolutely furious. Fortunately, he’d had the sense enough to take the precaution of writing a DVD with the contents of those files, and so managed to avert a complete tragedy. But when he rang me to say: “You’ll get a good story out of this, Guy!” I had to disappoint him.

“Robert,” I said, sadly, “you’re making a very simple mistake. You don’t want a backup service. You want an archive service!” You will remember the difference, won’t you?

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