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SAN replication : WAN bandwidth sizing & comparison to MS SQL mirroring

Posted on 2012-03-19
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Last Modified: 2012-03-30
I have a need to mirror a Production MS SQL DB to a remote hot site.

Q1:
Would SAN replication be more efficient (ie requires less bandwidth
& less manual intervention in the event disaster strikes the Production
site) than MS SQL 2008 mirroring ?

Q2:
Currently we have MS SQL log shipping with the SQL log ship files being
sent over a 50Mbps WAN at regular intervals to DR site (I suppose this
is to update the DR database as I'm new to this project).  Can I base
the bandwidth required by taking the largest log ship file ever created
divided by the interval that the log ship file is being created?
Can this method of sizing the WAN bandwidth be used for both
SAN replication as well as MS SQL mirroring solutions?
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Question by:sunhux
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by:lcohan
lcohan earned 265 total points
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"I have a need to mirror a Production MS SQL DB to a remote hot site."


In my opinion SAN replication will not work in your case and your best option would be: "Database Mirroring"  high-performance mode (runs asynchronously) OR high-safety mode (synchronous)

http://msdn.microsoft.com/en-us/library/ms189852.aspx
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lcohan earned 265 total points
ID: 37738963
Please see "SAN-over-WAN Applications Assessment" from link below to help you answer the two questions above. It is an older article but principles still stand today and as a side note my above answer is based on failure from our data center, SAN vendors(s) to ACTUALLY make it work not just as described by product(s) features - all recovery tests failed on the "replicated" SAN snapshots therefore we dropped it and (still) rely on old good SQL method including log shipping you currently have in place. Its all about how much data you can afford to loose and that dictates your log shipping or mirroring scenario. You could choose high safety if you can't afford any data loss and its working perfectly (for me on SQL 2005 and 2008 since 2010) including periodic disaster/recovery testing.

http://www.qlogic.com/Resources/Documents/WhitePapers/Routers/SN0130937-00.pdf
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by:Shani Basha
Shani Basha earned 110 total points
ID: 37741495
In my opinion you can have SAN replication with compression and deduplication which saves WAN bandwidth

Recently lot of Enterprise storages and FC switches available in the market which supports these features

http://www.hds.com/groups/public/documents/webasset/hitachi-replication-solution.html?M=data-replication-solutions-cal
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by:Racim BOUDJAKDJI
Racim BOUDJAKDJI earned 125 total points
ID: 37744921
Q1/No.  Since SQL 2008 database mirroring is fully compressed, it actually works better than SAN replication since it guarantees better transactional coherence between the databases.  SAN has no clue of transactional coherence.
Q2/No.  Log shipping is file based while mirroring is stream based.  Mirroring is more comparable to replication.  Plus mirroring is compressed.
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