July 14, 2010 at 7:47 am
Does anybody know whether there is a difference in the overall network traffic created between log shipping and mirroring?
We currently use log shipping with log backups every 15 minutes, but are looking into changing to mirroring. I have been looking into the network traffic caused by each by looking at the total size of the log backups over each 1 hr period and comparing it to the log bytes flushed/sec perfmon counter and converting both to MB/hour to give a direct comparison. For each 1 hour period, using the same database, the total calculated from the log bytes flushed/sec is approx 50% less than that for the tran log backups.
Does anybody know if this is to be expected or am I missing something?
Thanks in advance.
July 19, 2010 at 9:07 pm
My guess in your findings is that the bytes would be less for mirroring because the logs are compressed before shipping with SQL Server 2008 and SQL 2008 R2. You may be able to achieve the same metric by compressing your log backups when you take them as part of your log shipping config.
In SQL 2005, they were not compressed in mirroring, so I would think you wouldn't see much difference, if any, if switching between log shipping and mirroring for SQL 2005 as far as network traffic.
From http://msdn.microsoft.com/en-us/library/cc645581.aspx:
Compression of the stream of transaction log records.
The principal server compresses the stream of transaction log records before sending it to the mirror server. This log compression occurs in all mirroring sessions.
I think that's the information you were looking for.
Cheers,
Steve
July 22, 2010 at 9:33 am
Yeah, that makes sense.
Many thanks for your assistance.
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