[OpenIndiana-discuss] Very slow write performance on a 3 disk raidz1-0 zpool

[Robbie Crash]

Are you using compression or dedup on the FS?

On Fri, Aug 24, 2012 at 12:58 AM, Jan Owoc <jsowoc at gmail.com> wrote:

> Hi,
>
>
> On Thu, Aug 23, 2012 at 10:32 PM, Julius Roberts
> <hooliowobbits at gmail.com> wrote:
> > as per the subject, I'm getting very slow write performance on a 3
> > disk raidz1-0 zpool.  IIRC the disks are early 1tb WD green drives.
> > Not sure what i should tell you, but during copies of large 10gb+
> > files rsync is showing around 2MB/s, which is terribly poor i think.
> > Sorry if this is a common question, not sure what to do.
> >
> > twsadmin at darling:~/mdbackup$ zpool iostat Backups 5
> >                capacity     operations    bandwidth
> > pool        alloc   free   read  write   read  write
> > ----------  -----  -----  -----  -----  -----  -----
> > Backups     2.04T   694G     97    330  2.72M  1.95M
> > Backups     2.04T   694G    170    248  3.98M  1019K
>
> How are you generating these writes? Are they maybe small files over a
> wireless network? If so, what if you generated the I/O using:
> dd if=/dev/zero of=/Backups/zero.file
>
> Is this behaviour new, or did you change anything recently? (Did you
> really copy over all those GBs at 2MB/s?) I'm going to rule out
> underpowered system, since even an Atom should be able to do sha256
> checksums and parity calculations faster than 2 MB/s.
>
>
> > twsadmin at darling:~/mdbackup$ zpool status
> >   pool: Backups
> >  state: ONLINE
> >   scan: scrub repaired 0 in 12h56m with 0 errors on Sat Aug 18 20:56:44
> 2012
> > config:
> >
> >         NAME        STATE     READ WRITE CKSUM
> >         Backups     ONLINE       0     0     0
> >           raidz1-0  ONLINE       0     0     0
> >             c3t0d0  ONLINE       0     0     0
> >             c3t1d0  ONLINE       0     0     0
> >             c4t1d0  ONLINE       0     0     0
>
> This looks fine. Reading 2TB in 13h is about 45 MB/s, so about the
> order of magnitude we'd expect.
>
>
> Jan
>
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>



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