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

[Bryan Iotti]

Are these Advanced Format Drives (4k sectors) already?

My own WD Caviar Green 2TB sucked bad before I recreated a pool on it with
the modified zpool-12 command.

You could run:
# zdb <pool name> | grep ashift

And see what value you get. If you have 9, the pool is structured for 512
byte sectors and a 4k drive could suffer a performance loss. For a 4k
drive, the ASHIFT value should be 12.

Hope this helps,
    Bryan
On Aug 24, 2012 7:04 AM, "Robbie Crash" <sardonic.smiles at gmail.com> wrote:

> 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
> >
> > _______________________________________________
> > OpenIndiana-discuss mailing list
> > OpenIndiana-discuss at openindiana.org
> > http://openindiana.org/mailman/listinfo/openindiana-discuss
> >
>
>
>
> --
> Seconds to the drop, but it seems like hours.
>
> http://www.openmedia.ca
> https://robbiecrash.me
> _______________________________________________
> OpenIndiana-discuss mailing list
> OpenIndiana-discuss at openindiana.org
> http://openindiana.org/mailman/listinfo/openindiana-discuss
>