Losing data is something that none of us want to happen. Ever. Even trivial pieces of data might not really impact my life, but if I can't find something, it's really, really bothersome to me. I think it's why I have a 4GB Outlook file and lots of old files stuck in my "Documents" folders.
However losing data at work is a problem. As SQL Server professionals we try hard to prevent this, and usually counsel others to do the same. I've felt bad the many times that I've had to give someone the bad news that because they didn't make a backup, they can't recover their system.
Awhile back someone stumbled on this thread from 2005 over at AV Science Forum. It's a geek site for various topics, but they had to restore from backups, and lost a bunch of data. Not to beat on MySQL since I think this was just a bad situation, but apparently there was a corruption issue that crept into their system after an upgrade, they didn't catch it, a number of backups were run, and finally it was noticed for some reason. They had done backups, but all the backups since the upgrade were corrupted. Eventually they went back a day and found a good backup they could use to restore things.
That makes me wonder what would have happened if this had gone on for more than a week? Would they still have backups? What if they were doing disk only backups and they exceeded their retention window? It's one reason I'm wary of disk only backups. They're expensive and you might shorten your retention window more than with tape.
This is a good lesson in why you want to periodically test your restores, and why you need to examine the output from DBCCC CHECKDBs run on your databases on a regular basis. You never know when a disaster will strike and you need to recover data.
It's possible that you'll still lose data somehow, but a SQL Server professional will be doing their best to ensure if rarely happens.
Steve Jones
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