Hi, I'm trying to figure out a ZFS read performance issue that I am seeing on FreeBSD9.2 (amd64). CPU: Intel(R) Xeon(R) CPU E5405 @ 2.00GHz (2000.11-MHz K8-class CPU) real memory = 4294967296 (4096 MB) avail memory = 4059762688 (3871 MB) I have an LSI 9240-8i controller. (8ports @ 6GB/s ea, x8 PCIE 2.0) with the drives installed JBOD. These are intended for use as a storage pool. The main system drives are using the onboard SATA controller for the system.
With a single drive formatted UFS, I can achieve ~ 175MBps Read and Write speeds using dd as follows: WRITE: dd if=/dev/zero of=/vol0/test bs=1m count=10000 READ dd if=/vol0/test of=/dev/null When I create a zfs pool with a single drive: zpool create vol0 /dev/mfisyspd0 using dd again, I can write ~175MBps, but my read speed is only about 60MBps. I have set vfs.zfs.prefetch_disable = 0 and this improves reads to about 70MBps, but no much beyond that. Now, this gets even more interesting. If I add a drive to the pool: zpool add vol0 /dev/mfisyspd1 My write speeds increase to ~280MBps, but my read speed is still about 60MBps. Using gstat, I can see that the load is shared pretty equally amongst the drives. This trend continues with the addition of a 3rd and 4th drive with write speeds ramping up to about 500MBps (I didn't test past that), but read speeds stuck around 60MBps. I have done similar testing under 9.1 making sure to align 4K sectors using the gnop trick (I am using WD RED 3TB AF drives) with no change. I have looked through the wiki and handbook for tuning and done some googling around, but I'm pretty much out of ideas now. Everything I have read seems to indicate that ZFS should run fine on 4GB without any tuning, and at this point I haven't even begun any serious stress testing. Any ideas of where to go from here would be greatly appreciated. Thanks, -Markham --- [1]Markham Breitbach Network Operations SSi People, Ideas, Technology - - - - - - - - - - - - - - - - - - - - - +1 867 669 7500 work +1 867 669 7510 fax [2]markham_breitb...@ssimicro.com [3]www.ssimicro.com 356B Old Airport Road Yellowknife , NT X1A 3T4 Canada - - - - - - - - - - - - - - - - - - - - - Visit some of our other networks [4]www.qiniq.com & [5]www.airware.ca References 1. http://www.ssimicro.com/ 2. mailto:markham_breitb...@ssimicro.com 3. http://www.ssimicro.com/ 4. http://www.qiniq.com/ 5. http://www.airware.ca/ _______________________________________________ freebsd-performance@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-performance To unsubscribe, send any mail to "freebsd-performance-unsubscr...@freebsd.org"
