RAID levels for system databses?

  • What are the best suitable RAID levels apply for system DB?

  • Hi there

    I'd recommend RAID 1 - the mirroring will give you failover and won't affect read/write performance.

    Mike.

  • so for all system db RAID 1 ?

    anyway Thanks Mike.

  • Yes, RAID 1 for all system databases.

    Give special consideration to tempdb - ideally this will be on the fastest disks you can buy. If this can go on separate RAID 1 to master, model, and msdb all the better.

    Mike.

  • RAID 1 on a good RAID controller most certainly will affect read performance. It will multiply theoretical throughput and MaxIOPS by n times over the performance of a single disk. n being the number of disks in the array. That's theoretical performance, real-world gains will be less, but similar.

    However, I'm not sure that recommending RAID 1 for TempDB for all instances is good advice either. There are certainly other RAID levels to consider, depending on what your environment is like.

    For best performance I would use RAID 10. It will improve write performance, and maintain equal read performance as RAID 1 (assuming the same number of total disks). If you are limited by total number of disks you can use, and need to use less than 4 for the tempdb and model databases, than RAID 1 is your best bet. If you plan on using 4 or more, I would use RAID 10.

    RAID 5 or 6 are also viable options depending on your requirements, but I wouldn't use them unless you really need to get the most out of your total disk capacity, and have lower requirements for IOPS.

  • Hi club

    I take your points on board. But without a full picture of the specifications available etc it's difficult to give a detailed recommendation. RAID 1 is a good catch-all for O/S and system DB drives which I've implemented successfully in the past.

    However, I have also configured RAID 5/6/10 when necessary too. It's all a matter of budget!

    Mike.

  • It is a good catch-all, but the way I read your post made it sound as though it was the only correct option, or a best-practice at least. I just wanted to clarify that a bit.

  • No worries, I'll try to make things clearer next time. Cheers!

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