Mirroring: Enterprise Vs Standard Editions

Question

We plan to implement database mirroring on SQL 2008 in the near future, but we have not made the purchse yet.

 

I was reading the Mircrosoft comparison sheet and it shows that both Enterprise and Standard support DB Mirroring, but it says that Enterprise is "FULL" and Standard is "Single Thread".  We will have approx 8 databases that will need to be mirrored.  What, exactly, is the difference with the two editions regarding mirroring?

Answer 1

Hi Brad,

Single Thread in standard edn means that transactions will get sent over a single thread.  This can hinder performance in full mode as full mode has to wait for a response from the mirror.  If you have large amounts of transactions it is recommended that safety is set to off.  So that the principle does not need to wait for a response from the mirror.

Basically, if you have a large volume of transactions you want to go for Enterprise Edn.

Hope this helps

Steve

Answer 2

Hi,

1) You can configure E.E and S.E also.if your using 32 bit systems database mirroring can support a maximum of about 10 databases per server instance of the numbers of worker threads that are consumed by each database mirroring session.

2) And Database mirroring is not supported with either cross-database transactions or distributed transactions.

Answer 3

If we are talking about Thread limitation, Enterprise edition will use 'Parallel Redo' for every 4 extra core while recovery of Mirror database, but Standard cant use this feature.

Also, in both 32 & 64 bit system, a principal database will use 1 Global thread+ 2 dedicated threads for mirroring activities. For Mirrored database, in 32 bit, its 1+10 and 1+2+(total no of logical cpu - 4) * 1 in 64 bit.

Witnese will use 2 threads.