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Exchange 2010 Replication using VVR

Created: 09 May 2011 • Updated: 15 Jun 2011 | 2 comments
pkumare's picture
This issue has been solved. See solution.

Hi,

I have a general doubt on VVR replication methodology.

I know that VVR is working on the block level replication and any change in the block it will replicate to DR site.

I am proposing to one of my customer the below configuration,  Exchange 2010 Standalone Server + SFW + VVR in primary and same at DR.

But I heard a challenge which I have to check here that any of you facing it / work around.

Issue is, Every day Exchange 2010 will perform database maintenance activity which in turns re write the entire blocks. so my doubt is whether VVR will do a Full sync after this, or it has any Intelligent to understand the Exchange Activity. 

I have 10 TB of data in the server, it will be very tough to do a full replication to DR 

Awaiting your Feedbacks.

Thanks a lot.

Praveen

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mikebounds's picture

VVR has some intelligence of the filesystem (so can replicate just used blocks on an initial sync), but knows nothing about the application.  Also I am fairly certain that VVR does not read the current contents of a block before writing it to the SRL - i.e if a certain Block contains data "X" and you are writing the same "X" to it, then as VVR almost certainly does not read the current contents it does not know it is not actually changing the block.  For VVR to read each block, would put an extra overhead on VVR and almost certainly there will be some blocks changing during this maintenance (even if database is not open, Exchange will probably be writing blocks somewhere to denote progress of the maintenance), so VVR couldn't just assume that no blocks change during this process.   I don't understand what the point is of Exchange re-writing each block - what does this acheive?

Note VVR normally replicates continoulsy so would not do a full resync after DB maintenance but would replicate during the maintenance, but will probably get behind during this period and then catch-up from the SRL. 

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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SOLUTION
Wally_Heim's picture

Hi Praveen,

Once the volumes are fully synced, VVR only replicates writes that happen to the primary volumes.

Exchange does run database consistency checks on its information stores on a regular interval or when the server is inactive.  However, I doubt that Exchange is re-writing the entire information store, atleast I have not seen this activity before. 

Exchange will compact or defrag the infromation store which will cause a high number of writes but during these processes it does not re-write the entire information store.  Basically the compact/defrag operations only happen for new mail that has arrived or been deleted since the last run of the compact/defrag operation.  This should be far less than the entire information store.

Thanks,

Wally