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 backup restore

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craker
Starting Member

5 Posts

Posted - 2010-01-12 : 13:22:55
Hi everybody, i am new in this forum. I am spanish student that i am studing databases. Sorry if my english is horrible.

I need help. I made one database about spanish census. I must to describe the back-up plan for my aplication taking into account that this aplication must be enable 24 hours each day. I dont know how can i do this.

Please, any help is welcome. Thanks very much

tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2010-01-12 : 13:27:57
Here's our backup plan:

Full backup nightly
Diff backup 12 hours after full backup
Tlog backups every 15 minutes

Tara Kizer
Microsoft MVP for Windows Server System - SQL Server
http://weblogs.sqlteam.com/tarad/

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Kristen
Test

22859 Posts

Posted - 2010-01-12 : 13:48:22
"Diff backup 12 hours after full backup"

Do you feel strongly about that Tara?

I presume its to reduce the number of TLog backups files you have to restore if you have a disaster in second half of the day, but at a cost of quite a lot of / some disk space?

(Our DIFFs are a horrifically high percentage of the size of a FULL backup even just a few hours after FULL backup, maybe yours are a lot calmer )

Do you not bother to back the DIFFs up to tape? (seems quite a lot of hassle / additional complexity to design the backup that way, but the mid-day DIFF is not much use tomorrow or thereafter, if you have all TLog backups?)

I still think folk should do TLog backups every 10 minutes, not 15
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tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2010-01-12 : 13:53:33
We run differentials only on a few systems and yes it's for recovery reasons of not having to apply so many tlog backup files.

Our diffs can be big too, but we don't worry about how much disk space we use. They say disks are cheap, although our SAN team would argue with that.

We backup all of our SQL backup files to tape. We don't exclude the differentials in case the point in time recovery is a few days in the past.

We do our tlog backups every 15 minutes as 15 minutes is our pain threshold for data loss.

Tara Kizer
Microsoft MVP for Windows Server System - SQL Server
http://weblogs.sqlteam.com/tarad/

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"Let's begin with the premise that everything you've done up until this point is wrong."
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Kristen
Test

22859 Posts

Posted - 2010-01-12 : 14:00:36
10 minutes loss would be less pain ... but I'll not try to push you on that
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tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2010-01-12 : 14:05:16
We weigh pain threshold of data loss with the time it takes to do a recovery. Restoring tlog files is faster with 15 minute backups than it is with 10 minute backups. Data loss is extremely rare, definitely more rare than a recovery which rarely happens too. Throwing in differentials into the mix helps us recover faster too.

Tara Kizer
Microsoft MVP for Windows Server System - SQL Server
http://weblogs.sqlteam.com/tarad/

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"Let's begin with the premise that everything you've done up until this point is wrong."
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Kristen
Test

22859 Posts

Posted - 2010-01-12 : 15:32:02
Good point. I hadn't considered it from that angle before.
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