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 which restore option is valid?

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nanolin8
Starting Member

17 Posts

Posted - 2012-06-20 : 21:25:10
We have a sql database which has two backup methods are in place. One is regular backup by sql server to disk with full db backup at 11pm daily and hourly Tlog backup 12:00am to 11:59pm. It also has full db backup (w/o Tlog backup) to virtual device via netbackup tool at 9:30pm daily. I would like to know which option below is valid if we need restore the db to 9:40pm?

option 1: use previous day 11pm db backup plus Tlog backups from 12:am to 10pm to make a complete restore

option 2: use current day 9:30pm db backup plus 10pm tlog backup to make a complete restore(In this case, two files are obtained by different tools).

option 3: use current day 9:30pm db backup, but only can restore to 9:30pm, not 9:40pm since tlog backup can't be applied.

Please advise.

Thanks!

nigelrivett
Master Smack Fu Yak Hacker

3385 Posts

Posted - 2012-06-21 : 03:58:51
You can use any of the full backups with all of the following tr log backups. The tr log backups are independent of the full you just need the complete sequence. It doesn't matter how the backups are taken.

So 1. is ok, 2 is ok,
3. You can do that but yoou can also apply the log backups

But you shoould know this from testing.
If you haven't tested it then you don't know if any of these will work.
If you don't periodically test it then you don't know if it still works.
When it's needed is not a good time to find if any of your backups are valid.

==========================================
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SSIS can be used in a similar way.
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nanolin8
Starting Member

17 Posts

Posted - 2012-06-21 : 09:45:21
Nigelrivett,

Thank you for your reply. Are you saying the following tlog backup will start from the last SCN of previous Tlog backup instead of last SCN of most recent db backup? is this why Tlog backups are independent from db backup?

You are right, we should test the restore. But I would like to get it straight in theory.

When we do testing, as long as the restore process doesn't generate error, does that mean it is successful? Since I don't know the application, I can't identify if any transactions are missing from data perspective.

Thanks again!



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