December 16, 2011 at 7:57 am
We have an environment which has database close to 500 GB. The log backups generate about 80-90 GB worth of logs.
Problem we are facing is that copy process lags behind due to bandwidth from primary to DR site.
Wondering if Mirroring will have any benefits vs log shipping ?
December 17, 2011 at 5:50 am
If you opt for ‘High Safety’ mode of Mirroring, your Primary Server will perform slowly (because of low bandwidth). I don’t feel you will get any significant advantage in ‘High Performance’ mode as compared to Log Shipping.
My only recommendation to you would be reconsidering high bandwidth for Primary to DR site. You are risking high availability of your database by saving few bucks (low bandwidth network).
December 17, 2011 at 6:11 am
Maybe. What you haven't mentioned is the frequency of the log backups which is important. 90GB every 15 minutes is huge. 90GB a day, not so much.
To determine, work out what the peak kB/s or MB/sec of log generation is (either by looking at the log backups or looking at the log usage % with DBCC SQLPERF(LogSpace)) and then comparing that with the available bandwidth you have.
Also bear in mind that SQL 2008 compresses database mirroring log records whereas your log backups (unless you're manually compressing them) are going across uncompressed, so mirroring will likely be using less bandwidth overall.
Best way is to test. Can you set up a test server in the same site as your primary, another in the DR and simulate the production load and see how the network copes?
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
December 18, 2011 at 2:26 pm
chopperGuy (12/16/2011)
We have an environment which has database close to 500 GB. The log backups generate about 80-90 GB worth of logs.Problem we are facing is that copy process lags behind due to bandwidth from primary to DR site.
Wondering if Mirroring will have any benefits vs log shipping ?
Mirroring can be extremely sensitive to network latency. Have you considered compressing your log backups and even increasing the frequency?
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