ZFS on USB raidz very slow
807557Dec 18 2008 — edited Jan 16 2009Hi,
I have migrated a raidz pool on three USB disks from a Mac to a Dell PowerEdge T105 running Solaris update 5. ZFS was upgraded. It now supports version 10 pools. The raidz pool has version 8.
The performance of the pool is very poor. My last test consisted of making a copy of a file of over 600MB. The throughput was no more than 1MB/s. Now and then there are peeks of high performance. At one occasion I had a 20MB/s for a read of a 1.7GB file.
On the Mac the pool was also sometimes slow, but in general it was very fast. However, on the Mac mounting the pool was rather unpredictable. There were often panics or degraded mounts. When the pool was online there were two possible situations. Either the three disks would be active together when there was activity. In that case the pool was well mounted and very fast. Or the disks would not be active together, i.e. the leds of two of them would blink almost synchronously, while the third disk would be almost inactive. That is when the pool would be very slow and it is this behaviour I have on the Solaris box. On the Mac a reboot or two helped, but with the server that doesn't seem to have any effect (an undesirable solution anyway). Exporting and re-importing doesn't either.
Does anyone have the same kind of problem or is there a solution for this?
Best regards,
Werner.