In article <41336CB1.6030105@xxxxxxxxxxxxxx>,
Timothy Miller <miller@xxxxxxxxxxxxxx> wrote:
Timothy Miller wrote:
Hey, that rings a bell. I have a 3ware 7000-2 controller with two WD1200JB drives in RAID1. I find that if I dd from the disk, I get exactly the read throughput that is the max for the drives (47MB/sec). However, if I do a WRITE test, the performance is miserable.
I have been going back and forth with 3ware for months, and what's odd is that my drives with my controller in any machine other than the primary box get great write throughput, BUT on my main box with 1G of RAM, I get MISERABLE write throughput. When I should be getting 36MB/sec or faster, I get 8 to 12 MB/sec.
Now, I have tried limiting the memory with a mem= boot option, but that doesn't change the performance any.
Scratch all this. Even if I physically remove half the memory, I STILL get the performance problem.
3ware eh?
Try setting /sys/block/sda/queue/nr_requests to twice the number
in /sys/block/sda/device/queue_depth