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Backup Sqlserver 2008

Mortarello used Ask the Experts™

I have my log file size of 800 mb and i did a backup. The Backup is fine but my log file still the same size. because I thought after the backup, the log file size would be less.

Am i correct ?

Many Thanks
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SQL Service Manager
yes correct but if you do a backup while the system is running hard then there is the probability to have the emptied part of the log between used parts of the log file and you cannot decrese the size when you shrink it. to check that run


if you have LSN's with status 2 at both the start and end of the list and in between 0. then it means emptied logs are between used logs and you cannot delete emptied logs. in such a case run log backup again and check with DBCC LOGINFO until you have 0 statused LSN's at the end. after that shrink the log file.


Tks, I did the backup 3 times and shrink.

Now file size is 15 mb. :)

Guy Hengel [angelIII / a3]Billing Engineer
Most Valuable Expert 2014
Top Expert 2009

no, not correct.

the LOG BACKUP will NOT decrease the log file size .... just mark the space used internally as reusable.
the FULL BACKUP will not act on the log file at all in that regards.

note: you should, in regular operations, NOT try to regularly reduce the log file, as that will just require the db to increment the file size again ...
instead, make sure you just run LOG backups regularly enough.



You mean that if I do regular log backup. The file is not going to grow because he is going to use the reusable area ?

Tks angelll.
Metehan OzculluSQL Service Manager

yes it will use the emptied log area. to get that area back to os you should shrink the file.



Thank you very much  mozcullu and angelIII