Hello,Can somebody point me to any guidlines which would suggest on When togo for Clustering and when to go for Mirroring in Sharepoint and the Advantages disadvantages/risks involved in both scenarios.I have a white paper on mirroring for MOSS http://technet.microsoft.com/en-us/library/cc262910.aspx. Is there a similar white paper for MOSS 2007 on clustered SQL environment ?Thanks,siajsiaj

I sort of feel like mirroring is not recommended. I can't find anything to back that up though. As far as I know, everyone uses clustering. Hopefully someone can jump in with better details.--Paul Galvin, Arcovis Microsoft MVP - SharePoint Blogging @ http://feeds.feedburner.com/PaulGalvinsSharePointSpace Twitter @ http://www.twitter.com/pagalvin

Hi siaj, There are no instructions specific to setting up clustering for Office SharePoint Server 2007. For instructions on how to set up failover clustering, see Installing a SQL Server 2008 Failover Cluster When you consider which high availability approach to choose, I suggest you read the document: Plan for availablity http://technet.microsoft.com/en-us/library/cc748824.aspx I list the main differences between clustering and mirroring below for your reference: Clustering Failover clustering provides availability support for a complete instance of SQL Server. A failover cluster is a combination of one or more nodes or servers, with two or more shared disks. A failover cluster instance appears as a single computer, but has functionality that provides failover from one node to another if the current node becomes unavailable. Office SharePoint Server 2007 references the cluster as a whole, so that failover is automatic and seamless from the perspective of SharePoint Products and Technologies. Synchronous database mirroring Database mirroring provides availability support by sending transactions directly from a principal database and server to a mirror database and server whenever the principal databases transaction log buffer is written to disk. We recommend that you use high-availability database mirroring, also referred to as high-safety mode with automatic failover. Each technology has advantages and disadvantages. Clustering is easier to implement but can be more expensive. SQL Server mirroring is not supported for Microsoft Office Project Server 2007 databases. The following table compares failover clustering to SQL Server high-availability mirroring. SQL Server failover clustering SQL Server high-availability mirroring Mirror takes over immediately upon failure. Mirror takes over immediately upon failure. Transactionally consistent. Transactionally consistent. Transactionally concurrent. Transactionally concurrent. Shortest time to recovery (seconds to minutes). Slightly longer time to recovery (seconds to minutes). Failure is automatically detected by database nodes; SharePoint Products and Technologies references the cluster, so that failover from a SharePoint Products and Technologies perspective is seamless and automatic. Requires scripting to achieve SharePoint Products and Technologies failover. Does not protect against failed storage, because storage is shared between nodes in the cluster. Protects against failed storage because both the principal and mirror database servers write to local disks. Requires more expensive shared storage. Can use less-expensive direct-attached storage (DAS). Same subnet. Up to 1 millisecond (ms) in latency between SQL Server and Web servers. Can use SQL Server simple recovery model, although the only available recovery point if the cluster is lost will be the last full backup. Requires SQL Server full recovery model. No performance overhead. Introduces transactional latency. Adds memory and processor overhead. Minimal operational burden. Additional operational burden, including scripting and setting up SQL Server aliases. Hope this helps. Lu Zou

Thanks Paul/Lu for the information.I too went through this article and getting more convinced that mirroring is still not ripe for MOSS 2007.Thanks.siaj

Very useful and informative posts. Thank you for the question as well as the answers. I found these links useful http://technet.microsoft.com/en-us/library/cc748824.aspx http://technet.microsoft.com/en-us/library/ms191309.aspx http://technet.microsoft.com/en-us/library/cc990273.aspx http://technet.microsoft.com/en-us/library/ms189852.aspx http://www.dern.com/Dern_CDW_NetComm_2008_0618_BusinessContinuity_l04-07_NC42151.pdf Thanks. Mpumelelo