I ran a quick test to confirm James theory - and there is more weirdness
# Mirror pool with two 500GB SATA disks - no log device
r...@m1-sv-zfs-1:~# zpool create pool1 mirror c8t5d0 c8t2d0
r...@m1-sv-zfs-1:~# zfs create pool1/fs
r...@m1-sv-zfs-1:~# cd /pool1/fs
r...@m1-sv-zfs-1:/pool1/fs# time dd if=/dev/zero of=bigfile.55 bs=4096
count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 41.2861 s, 99.2 MB/s
real 0m41.290s
user 0m0.634s
sys 0m12.907s
# Mirror pool with two 500GB locally attached SATA disks - with log device
r...@m1-sv-zfs-1:~# zpool add pool1 log c8t4d0
r...@m1-sv-zfs-1:~# zpool status pool1
pool: pool1
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
pool1 ONLINE 0 0 0
mirror ONLINE 0 0 0
c8t5d0 ONLINE 0 0 0
c8t2d0 ONLINE 0 0 0
logs ONLINE 0 0 0
c8t4d0 ONLINE 0 0 0
r...@m1-sv-zfs-1:/pool1/fs# time dd if=/dev/zero of=bigfile.55 bs=4096
count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 51.0463 s, 80.2 MB/s
real 0m51.107s
user 0m0.639s
sys 0m12.817s
r...@m1-sv-zfs-1:/pool1/fs# time dd if=/dev/zero of=bigfile.66 bs=4096
count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 52.0175 s, 78.7 MB/s
real 0m52.022s
user 0m0.641s
sys 0m12.780s
Performance dropped for some reason and still no io activity on the log device
(c8t4d0 - Transcend 8GB SSD disk)
TIA
Dushyanth
--
This message posted from opensolaris.org
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
