On 16 Listopad 2011, 2:21, Cody Caughlan wrote: > How did you build your RAID array? Maybe I have a fundamental flaw / > misconfiguration. I am doing it via: > > $ yes | mdadm --create /dev/md0 --level=10 -c256 --raid-devices=4 > /dev/xvdb /dev/xvdc /dev/xvdd /dev/xvde > $ pvcreate /dev/md0 > $ vgcreate lvm-raid10 /dev/md0 > $ lvcreate -l 215021 lvm-raid10 -n lvm0 > $ blockdev --setra 65536 /dev/lvm-raid10/lvm0 > $ mkfs.xfs -f /dev/lvm-raid10/lvm0 > $ mkdir -p /data && mount -t xfs -o noatime /dev/lvm-raid10/lvm0 /data > > --
I don't think you have a flaw there. The workload probably skews the results a bit on the master and slave, so it's difficult to compare it to results from an idle instance. The amount of data written seems small, but a random i/o can saturated the devices quite easily. I went with a very simple raid config - no LVM, default stripe size (better seeks, worse sequential performance), default read-ahead (could give better seq. performance). Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
