Danny Carroll wrote:

The initial results for a ICH9 vs Areca in JBod mode can be found here: http://www.dannysplace.net/ZFS-JBODTests.html

Summary: 5 Disk ZFS RaidZ array with atime turned off. ICH9 - block reads avg 400MByte/Sec ICH9 - block writes avg 150MByte/Sec ArecaJBOD - block reads avg 300MByte/Sec ArecaJBOD - block writes avg 160MByte/Sec

The Areca seems to be in all except char and block writes. Block reads are 75% as fast as the ICH9 and rewrites are about 85% as fast.

There seems to be little difference between enabling and disabling the disk cache on the Areca. This leads me to two conclusions: 1. Disabling the write cache does nothing on Seagate drives. 2. IO to the drives is so slow that a write cache is irrelevant.

These are just some quick tests that I started with, mainly to compare the areca bus versus the ich9 bus. If someone has any tuning suggestions, then now is the time to make them before I migrate the ICH9 drives to the Areca bus.

-D p.s. My OS details are: FreeBSD 7.1-PRERELEASE #3: Tue Nov 4 13:58:49 EST 2008 localhost# cat /etc/sysctl.conf kern.maxvnodes=400000 net.key.preferred_oldsa=0 net.key.blockacq_count=0 kern.ipc.maxsockbuf=400000 net.inet.ip.fastforwarding=1 net.inet.tcp.rfc1323=1 kern.ipc.maxsockbuf=16777216 net.local.stream.sendspace=82320 net.local.stream.recvspace=82320 net.inet.tcp.local_slowstart_flightsize=10 net.inet.tcp.nolocaltimewait=1 net.inet.tcp.delayed_ack=1 net.inet.tcp.delacktime=100 net.inet.tcp.mssdflt=1460 net.inet.tcp.sendspace=78840 net.inet.tcp.recvspace=78840 net.inet.tcp.slowstart_flightsize=54 net.inet.tcp.inflight.enable=1 net.inet.tcp.inflight.min=6144 net.inet.tcp.hostcache.expire=3900

localhost# cat /boot/loader.conf hw.em.rxd=4096 hw.em.txd=4096 vm.kmem_size="1536M" vm.kmem_size_max="1536M" smb_load="YES" smbus_load="YES" ichsmb_load="YES"