So, last week I managed to lose eight years’ worth of contact and calendar data. Coming less than three months after posting a blog entry entitled “My Backup Strategy Works!”, this is a little bit embarrassing.

I’ve been contacting friends and family to ask for the lost information, and many people have asked me how this data loss occurred. John Topley suggested that I “blog about how it went so catastrophically wrong, so that others might learn from your misfortune”, so here goes.

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I should explain that the vast majority of my personal data (photos, music, documents, etc) is duplicated on two external hard drives - a mains-powered one used by my desktop PC, and a portable USB one which I carry around the city and predominantly use with my laptop. I periodically synchronise most of the contents of these drives using SyncToy. Most of that data is then backed up to Mozy.com.

Where my data doesn’t naturally reside on these external hard drives (e.g. SQL Server databases), I try to ensure that I have scheduled tasks in place to periodically copy backups onto the drives. Unfortunately for me I failed to do this for my mobile phone, or for my laptop’s Outlook data. I didn’t worry about this too much though – the contact and calendar data on these two devices were synchronized on a daily basis, and what’s more my mobile phone was scheduled to back up to a 2Gb MicroSD card every evening.

So what went wrong? Human error, of course. I decided to rebuild my laptop, as it was getting a bit crufty. Then I ActiveSync’d it with the mobile phone, thinking that all the entries from the phone would be copied across to the laptop. But ActiveSync saw only already-synchronized entries on the phone which were not on the laptop, assumed that they had been deleted from the laptop, and synchronized the “deletion” over to the mobile phone. It would be nice to have a confirmation prompt when deleting a sizeable chunk of data!

Then, stupidly, I didn’t check the results of the synchronization. I didn’t realise what had happened until four days later when I went to send a text message. Guess how many days worth of Sprite Backup files I kept on the MicroSD card? Yup, three.

So, lessons learned:

  1. Consider all data (locations, devices) when designing a backup strategy.
  2. Verify data after performing unusual or large synchronizations.
  3. Keep more than three days’ worth of backups.
  4. Don’t write blog posts entitled “My Backup Strategy Works!”.