November 29, 2004 at 3:53 pm
I'm beginning a review of SQL Server 2005 Database Mirroring, and I have a few thoughts I'd like to throw out for discussion.
1. When would I use Mirroring instead of Clustering?
2. When would I use both Mirroring and Clustering together?
3. When would I use Database Snapshots with Mirroring to create a reporting server?
4. When would I use Replication instead of Mirroring and Snapshots?
Thanks in advance
Jon Baker
Principal Consultant
Evergreen Consulting of
Central Ohio, Inc.
November 30, 2004 at 12:10 am
SQL Users group in Melbourne, Australia recently covered all these topics in a SQL Server 2000 vs 2005 High Availability meeting. Though I haven't worked directly on clustering or mirroring, I managed to scribble a whole lot of notes, so here's some snippets from my interpretation of the technologies.
1. Mirroring provides automatic failover and failback between servers, and doesn't require SAN / NAS hardware from Microsoft's approved hardware list. Each Mirror server can use entirely separate hardware. Where as Clusters use shared harddisks (SAN / NAS) with the servers, creating a single point of failure. Clustering in 2000 required Enterprise edition of sql server and windows advanced server. No word from MS yet about what licensing will be required for Mirroring or clustering in 2005.
2. I don't think you would use Mirroring and Clustering together, unless you had two clusters being mirrored. Otherwise you would have a single point of failure.
3. You could snapshot the Server 'B' (the non active server) and report from the snapshot.
4. Replication allows you to have a greater distance between servers, ideal if you want to have highly responsive servers in local / international offices. There is a lag of at least a minute between the servers syncing themselves, and there are some database design considerations. But the benfits of a well organised replicated database means that each server can operate independantly and doesn't rely on the other server being constantly available.
I think there's notes from the presentation on http://www.sqlserver.com.au
Julian Kuiters
juliankuiters.id.au
January 3, 2008 at 1:47 pm
Just a note.... the link above to the PowerPoint Presentation is dead.
Does anyone have a new or active link to the presentation?
Yeah, I know I'm a little behind the power curve in looking for it now but it might help with some things I'm working on.
Thanks,
Tim
September 4, 2008 at 10:20 am
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