Snapshot of MSDB

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Snapshot of MSDB

vijayasankarb

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August 26, 2009 at 11:34 pm

#214310

Comments posted to this topic are about the item Snapshot of MSDB

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Joy Smith San SSC-Insane Points: 24877 More actions · Answer 1

Good question.

I am able to understand why snapshot cannot be created on TEMPDB. But don't understand why it has been prohibited for Master and Model (Though it's not necessary to create snapshots on system DBs).

Jon Cooney Old Hand Points: 329 More actions · Answer 2

The Microsoft 70-431 self-training book says "You cannot create Database Snapshots against system databases." Was this changed in a service pack, or was the author being lazy?

dun Say Hey Kid Points: 708 More actions · Answer 3

Yes, the MCTS 70-431 on p605 does say "You cannot create Database Snapshots against system databases." The MSKB at http://support.microsoft.com/kb/920926 does not have any errata for this page to indicate otherwise. Has anybody tried this on SQL 2005 Enterprise? What was the result?

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 4

dun (8/27/2009)
Yes, the MCTS 70-431 on p605 does say "You cannot create Database Snapshots against system databases." The MSKB at http://support.microsoft.com/kb/920926 does not have any errata for this page to indicate otherwise. Has anybody tried this on SQL 2005 Enterprise? What was the result?

Okay, I tried the following and it was successful.

create database msdb_dbss20090827 on

(name = MSDBData, filename = 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\msdbdata.ss')

as snapshot of msdb;

SQLRNNR SSC Guru Points: 281334 More actions · Answer 5

Also, this msdn article explicitly states model,master and tempdb as being prohibited - thus leaving the door open for msdb snapshots.

Jason...AKA CirqueDeSQLeil
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SQL RNNR
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Lynn Pettis SSC Guru Points: 442467 More actions · Answer 6

Lynn Pettis

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Points: 442467

August 27, 2009 at 10:48 am

#1045691

As does BOL (Books Online).

Steve Jones - SSC Editor SSC Guru Points: 736212 More actions · Answer 7

Steve Jones - SSC Editor

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Points: 736212

August 27, 2009 at 3:35 pm

#1045940

Thanks for the test.

TomThomson SSC Guru Points: 104773 More actions · Answer 8

Joy Smith San (8/26/2009)
Good question.
I am able to understand why snapshot cannot be created on TEMPDB. But don't understand why it has been prohibited for Master and Model (Though it's not necessary to create snapshots on system DBs).

It may not be necessary, but it can be useful - especially for MSDB. MSDB will grow like topsy unless job and jobstep history is pruned, but you want to avoid having oldest data disappear while you are generating reports about the history of jobs and steps (time taken, failures, scheduled runs missed,...) so that everything's viewed from the same base. So take a snapshot of MSDB and do the reporting against that - the real MSDB can happily be pruned while the report task is running. Throw the snapshot away when the report is done.

I'd always want to have a well documented history of model, what changed when and why it changed, and it should change so rarely that there is no point in taking a snapshot (snapshots are NOT backups, they are temporary static images you can play with). Probably sensible to ban taking snapshots as otherwise people might be tempted to misuse them. Probably the same applies to Master, although it changes more often.

Tom