Archive Log Mode
If I've said it once, I must have said it a billion times. Running a database in noarchivelog mode guarantees one thing and one thing only:
You will someday lose all of your data since your last full cold backup. Not might lose, not could lose, not likely will lose, not probably will lose - It means you WILL lose all of your data since your last full cold backup someday. (assuming of course, you haven't messed up your backups, in which case - you just lose your data period)
It happened again (sort of like clockwork). I believe I get an email like this once or twice a week at least. I feel sorry for them, but there isn’t too much one can do. I just got back from the Czech Republic last night, forced myself to stay up till 10pm east coast time (4am Czech time) but still got up on 5am and couldn’t get back to sleep. So, at 5:30am this morning, I read this (paraphrased):
We have one database in NOARCHIVE under version of xxxx. During night process heavy process is going on which is running since last 3 hrs. suddenly power was gone, UPS also not working. After receiving power when we start the database is is not started and giving following mess. We haven't any backup also. Backup was taken before 11 days back. If it is not recovered then, 11 days data entry will be made once again.
I feel really sorry for them, but I mostly feel sorry for the people that rely on this data – not so much for the DBA and technical team that
- made the conscious decision to run a production system in noarchivelog mode
- backs up so infrequently
They made these choices, purposely.
The only thing I can tell them now is “open a tar with support and see how much data you can scrape out of this instance” (I said that in this case based on other information in the email, I know the “fix”, we can get the instance open but only long enough to scrape out possibly inconsistent bits of data). I personally do not give recovery advice via email and tend not to do it on asktom either. You have to rely too much on the knowledge level of the person on the other end of the internet connection – far too easy for them to do something you never anticipated them doing and to REALLY mess up something big time.
Archivelog mode, it is the only thing that stands between you and your ability to recover your data in the event of a failure (well that and practice, practice, practice and – a test or two or three hundred).