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Sql Sever Async Replication Or EMC Mirror View

So - I already have an EMC San solution in place. I also have Mirror View running between my production site and my DR site. I am looking to implement a new SharePoint Enterprise SQL Server. The question is as follows - - am I better off using the inherent sql server mirroring asynch/log shipping or should I just be doing this at the EMC Mirror view level. I suspect I am safer using the built in Sql tools BUT that forces me to go to Enterprise Edition which cost mucho $$. I am going through the same analysis for Oracle. Any  help out there?
thanks!
Dave
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blattdavid
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blattdavid
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St3veMaxCommented:
Hi Dave,

All depends on your business requirements. We had the same issue with NetApp and it's own mirroring vs DB Mirroring. We have it so that when we do a transaction log backup every 15 mins; it initiates a SnapMirror to copy the backup just taken to the DR site.

HTH
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blattdavidAuthor Commented:
HTH
Do you have your DR Dbase in backup mode and apply the logs after the snap? Or are you just accumilating and will play forward in the event you need to. How do you feel about Doubletake also?
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St3veMaxCommented:
Doubletake = Crap (Based on my experience). It cannot work with RAID controllers; i.e. gurantee the write order across multiple RAID array's at the far end of the replication set. My testing based on ~20 DB's, each 10GB Each yielded 75% recovery rate over three different sample points. It's also a bandwidth hog (I know you can throttle during certain hours) which just adds to the "lag" on how far behind your data is.

As for DR DBase; All of our infrastructure is virtualised so it all off-line in a traditional sense; so in a DR situation; we present the VMFS volume to the blades; boot up the servers, do some network trickery and then present the LUN/Volume to the host. The software (SnapManager) then takes care of rolling forward the transactions to the latest available.

Whilst testing the above; I was also considering database mirroring which was a strong contender, however the business accepted that 15 mins + a couple for replication was enough so didnt look any further into mirroring.

HTH
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blattdavidAuthor Commented:
So you are using Snapview - - - just got  quote -

Why does double take ruin the write order? How does that lead to corruption on the DR End ?

Thanks so much!

I have a feeling that I am will be drawing the same conclusion as you - I just always feel uncomfortable the when the database itself (ie rmon in oracle) is not aware of what is really going on for Backup/DR - - -

Dave
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St3veMaxCommented:
Yep, NetApp SnapManager. I believe it's quite pricy.

Essentially I had the data and logs on different RAID controllers and so seperate RAID arrays. Double Take or HP OpenView Storage Mirroring (Same Product) captures these changes at the block level, but cannot gurantee the sequence in which it observed them across seperate RAID controllers and as such, when the block is replicated to the remote end; you can get issues where the data block is ahead of the log block when it should have been the other way round.

This then results in the LSN's being out of sequence when you try and attach the databases into SQL Server.

Of course, none of the above is an issue if you shut SQL down cleanly!

HTH

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