Le 2 oct. 08 à 09:21, Christiaan Willemsen a écrit : > Hi there. > > I just got a new Adaptec RAID 51645 controller in because the old > (other type) was malfunctioning. It is paired with 16 Seagate 15k5 > disks, of which two are used with hardware RAID 1 for OpenSolaris > snv_98, and the rest is configured as striped mirrors as a zpool. I > created a zfs filesystem on this pool with a blocksize of 8K. > > This server has 64GB of memory and will be running postgreSQL, so we > need to cut down ARC memory usage. But before I do this I tested the > zfs performance using iometer (it was a bit tricky getting it to > compile but it's running). > > So far so good. Figures look very promissing, with stagering random > read and write figures! There are just a few problems: every few > seconds, disk LED's stop working for a few seconds, except one disk > at a time. When this cycle is finished, it looks normal again. This > seems to be the flushing of the NVRAM cache. Should be solved by > disabling the flush...So far so good... > > But I also need the memory for PostgreSQL to work, so I added: > > set zfs:zfs_arc_max=8589934592 > > to /etc/system and rebooted. Now redid my test, with terrible > results.. sequential read is about 120 MB/sec. One disk should be > able to handle that, 14 disks should do more than a GB/sec, and in > my previous benchmark without the arc_max setting, they actually > make these figures...(even when not reading from ARC cache). Random > figures are not much better than this. > > So something is clearly wrong here... Can anyone comment?
This looks very unusual. Does it pass the hystereris test ? Set zfs_arc_max reboot low performace, undo the setting reboot, high performance. zpool status could help. zpool iostat 1. The read tests are threaded right ? -r > > -- > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
