zpool - low speed write

[Alex V. Petrov]

> 
> If only one of the dds shows bad throughput, then please:
> 
> - Install ports/sysutils/smartmontools and run smartctl -a /dev/XXX,
>   where XXX is the disk which has bad throughput
> - Try making a ZFS pool with all 3 disks, but then do "zpool offline
>   tank XXX" and then re-attempt the following dd:
>   dd if=/dev/zero of=/tank/test.zero bs=64k count=1000000
>   And see what throughput looks like.
> 

zpool destroy tank

zpool create tank ad8 ad10 ad12

dd if=/dev/zero of=/tank/test.zero bs=3M count=1000
1000+0 records in
1000+0 records out
3145728000 bytes transferred in 83.219741 secs (37800262 bytes/sec)

zpool offline tank ad10
cannot offline ad10: no valid replicas

zpool destroy tank

zpool create tank ad8 ad12

dd if=/dev/zero of=/tank/test.zero bs=3M count=1000
1000+0 records in
1000+0 records out
3145728000 bytes transferred in 126.873102 secs (24794286 bytes/sec)

dd if=/dev/zero of=/tank/test.zero bs=64k count=1000000
1000000+0 records in
1000000+0 records out
65536000000 bytes transferred in 1735.680273 secs (37758106 bytes/sec)

zpool destroy tank

zpool create tank ad8

dd if=/dev/zero of=/tank/test.zero bs=3M count=1000
1000+0 records in
1000+0 records out
3145728000 bytes transferred in 39.550739 secs (79536517 bytes/sec)

dd if=/dev/zero of=/tank/test.zero bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 90.810344 secs (72167990 bytes/sec)

=-O 

-----
Alex V. Petrov