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[Kevin Blackham <question170794@xxxxxxxxxxxxxxxxxxxxx>]

Question #170794 on Graphite changed:
https://answers.launchpad.net/graphite/+question/170794

    Status: Open => Answered

Kevin Blackham proposed the following answer:
Raid 5 and 6 are awful for write-heavy usage. Use raid-10 and a
controller with battery so you can safely enable write-back cache. Even
six spindles in level 10 will be a decent performer.

My 50k/min setup was 12x 7200rpm in a raid-10 on LSI low-end SAS. The
next upgrade was scrapped together from what I had available, and is 24x
5400rpm raid-10 on 3ware SAS. All with BBU, write-back enabled, and
auto-verify off. 256k stripe. The write-back gives the controller time
to reorder writes more efficiently than the kernel's scheduler can.

Oh, and use kernel's deadline scheduler, not cfq.

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