SQL Performance Optimization for SharePoint

Oct 20

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Saturday, October 20, 2012 11:05 AM  RssIcon

Design Tips

SQL Server databases are the largest consumers of disk space in SharePoint. Thus, designing your disk system for maximum performance at the database level is more crucial than for any other level. Here are some general design tips.

Don't virtualize SQL Server. If possible, don't virtualize SQL Server because it's already an integration platform. If you have to virtualize SQL Server, try to limit the virtualization to test or development systems. Avoid using it for production systems because it raises the bar in disk engineering to get good performance. SQL Server databases stored in virtualized disk files are inherently slow compared with dedicated physical disks.

Use multiple logical drive letters.It's usually a good idea to break up SQL Server databases into multiple logical drive letters because database files, transaction logs, backup files, and temporary databases (tempdb) benefit from having multiple independent sets of disk spindles. Adding more spindles spreads the load across multiple parallel operations when data is being written to the database.

If you're going to use a SAN or virtualized environment, make sure you understand where those logical drive letters will be mapped. For example, if the D, E, and F drives will all point back to separate LUNs on your SAN, but those LUNs will be part of the same storage group and same set of physical disks, splitting those files into multiple drive letters will add complexity without significant performance gains.

Use RAID 10 judiciously.RAID 10 is great, but you might not be able to justify it for all applications. For example, it might be overkill for backup files. Balancing disk performance and cost is a reasonable trade-off. One possible design is to use:

  • RAID 1 on boot disks
  • RAID 5 on data disks
  • RAID 10 on log disks
  • No RAID or RAID 5 on backup disks

Break large content databases into multiple database files.If you have large content databases, you can engineer better performance by breaking each large database into multiple database files. Each database file should be on a separate disk.

Presize SQL Server databases. SQL Server databases can be set to automatically grow as needed, but this can lead to massive file fragmentation. Presizing the databases to a sufficient size at the outset helps ensure contiguous file allocations. Note that SQL Server's tempdb database is heavily used by SharePoint, so you should presize it to about 20 percent of the size of the single largest content database.

If you want to use automatic database growth settings instead of presizing your databases, you should set the databases to grow in 50MB to 100MB clumps and not by percentage. Setting a 100GB database to grow in 10 percent increments means the database essentially stops to add 10GB or more on each increment. Using a small clump size will lead to more frequent, but smoother, steady state (i.e., continuous) growth.

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Categories: SQL, SharePoint