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tran log backup confused 2.5gb log file but 70gb log backup size


tran log backup confused 2.5gb log file but 70gb log backup size

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lawson2305
lawson2305
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Ok I have a question I have a 116gb DB the full backup ends up around 70.5GB in size I then perform a transaction log backup which the log file is 2.5GB in size but the log backup ends up being 71.5GB in size.

This is sql 2005 latest sp.
the db is in bulk logged recovery model.
Lynn Pettis
Lynn Pettis
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lawson2305 (6/9/2012)
Ok I have a question I have a 116gb DB the full backup ends up around 70.5GB in size I then perform a transaction log backup which the log file is 2.5GB in size but the log backup ends up being 71.5GB in size.

This is sql 2005 latest sp.
the db is in bulk logged recovery model.


Since the database is using the bulk logged recovery model, it looks like you may have had minimally logged operations. When you back up the t-log, the actual extends updated are backed up to the t-log backup. This keeps the t-log itself small but the backup can be much larger.

Cool
Lynn Pettis

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Managing Transaction Logs

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GilaMonster
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Bulk-logged recovery is why.
http://www.sqlservercentral.com/articles/Recovery+models/89664/

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Orlando Colamatteo
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Here is another article for your reference that helps explains why bulk logged is not reducing the size of your tlog backups:

Using Bulk Logged recovery model for Bulk Operations will reduce the size of Transaction log backups – Myths and Truths

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lawson2305
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Ok I have changed it to full recovery and the tlog is still running at 71GB. Does this make sense? Do I need to do something to get the tlog backup small like the actual tlog?

I have done a full db and tlog backup after changing to full recovery model.
Lynn Pettis
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What is the result of the following query.



select name, log_reuse_wait_desc from sys.databases;




Cool
Lynn Pettis

For better assistance in answering your questions, click here
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For Running Totals and its variations, click here or when working with partitioned tables
For more about Tally Tables, click here
For more about Cross Tabs and Pivots, click here and here
Managing Transaction Logs

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paul.knibbs
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Silly question--you're not backing up both the full and transaction log backup to the same file, are you? A SQL backup file can contain multiple backups.
lawson2305
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No I am not backing up to the same file.

full to a .bak
log to a .trn
lawson2305
lawson2305
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master NOTHING
tempdb NOTHING
model LOG_BACKUP
msdb NOTHING
ReportServer NOTHING
ReportServerTempDB NOTHING
ActivplantDB LOG_BACKUP
DLathrop
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If your database is heavily indexed, and you are rebuilding indexes frequently, this could account for the large log backups. This would especially be true if you have a small fill factor on some indexes, and its causing lots of page splits.

If that is the case, read:
[url=http://msdn.microsoft.com/en-US/library/ms189858(v=SQL.90).aspx][/url]

David Lathrop
DBA
WA Dept of Health
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