Grzegorz Jaśkiewicz wrote:
On Thu, Oct 30, 2008 at 3:27 PM, Christophe <xof@xxxxxxxxxxxx <mailto:xof@xxxxxxxxxxxx>> wrote:I'm a bit surprised to hear that; what would pg be doing, unique to it, that would cause it to be slower on a RAID-1 cluster than on a plain drive? yes, it is slower on mirror-raid from single drive.I can give you all the /proc/* dumps if you want, as far as computer goes, it isn't anything fancy. dual way p4, and sata drives of some sort.
O.k. that doesn't actually surprise me all that much. Software RAID 1 on SATA Drives for specific workloads would be slower than a single drive. It should still be faster for reads assuming some level of concurrency but not likely faster for a single thread. Writes would be expected to be slower because you are managing across two spindles, identical writes and SATA is slow for that type of thing.
Joshua D. Drake
-- GJ
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