Dear List,
I have a storage server running OpenIndiana with a number of storage
pools on it. All the pools' disks come off the same controller, and
all pools are backed by SSD-based l2arc and ZIL. Performance is
excellent on all pools but one, and I am struggling greatly to figure
out what is wrong.
A very basic test shows the following - pretty much typical
performance at the moment:
root@stor:/# for a in pool1 pool2 pool3; do dd if=/dev/zero of=$a/file
bs=1M count=10; done
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 0.00772965 s, 1.4 GB/s
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 0.00996472 s, 1.1 GB/s
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 71.8995 s, 146 kB/s
The zpool status of the affected pool is:
root@stor:/# zpool status pool3
pool: pool3
state: ONLINE
scan: resilvered 222G in 24h2m with 0 errors on Wed Dec 14 15:20:11 2011
config:
NAME STATE READ WRITE CKSUM
pool3 ONLINE 0 0 0
c1t0d0 ONLINE 0 0 0
c1t1d0 ONLINE 0 0 0
c1t2d0 ONLINE 0 0 0
c1t3d0 ONLINE 0 0 0
c1t4d0 ONLINE 0 0 0
c1t5d0 ONLINE 0 0 0
c1t6d0 ONLINE 0 0 0
c1t7d0 ONLINE 0 0 0
c1t8d0 ONLINE 0 0 0
c1t9d0 ONLINE 0 0 0
c1t10d0 ONLINE 0 0 0
mirror-12 ONLINE 0 0 0
c1t26d0 ONLINE 0 0 0
c1t27d0 ONLINE 0 0 0
mirror-13 ONLINE 0 0 0
c1t28d0 ONLINE 0 0 0
c1t29d0 ONLINE 0 0 0
mirror-14 ONLINE 0 0 0
c1t34d0 ONLINE 0 0 0
c1t35d0 ONLINE 0 0 0
logs
mirror-11 ONLINE 0 0 0
c2t2d0p8 ONLINE 0 0 0
c2t3d0p8 ONLINE 0 0 0
cache
c2t2d0p12 ONLINE 0 0 0
c2t3d0p12 ONLINE 0 0 0
errors: No known data errors
Ditto for the disk controller - MegaCli reports zero errors, be that
on the controller itself, on this pool's disks or on any of the other
attached disks.
I am pretty sure I am dealing with a disk-based problem here, i.e. a
flaky disk that is "just" slow without exhibiting any actual data
errors, holding the rest of the pool back, but I am at a miss as how
to pinpoint what is going on.
Would anybody on the list be able to give me any pointers as how to
dig up more detailed information about the pool's/hardware's
performance?
Thank you in advance for your kind assistance.
Best regards
Jan
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