[mythtv-users] Some master/slave backend advise required
Johan van der Kolk
johan.vanderkolk at gmail.com
Tue Jun 3 09:18:49 UTC 2014
On Tue, Jun 3, 2014 at 7:44 AM, Jean-Yves Avenard <jyavenard at gmail.com>
wrote:
> On 3 June 2014 15:35, Johan Van der Kolk <johan.vanderkolk at gmail.com>
> wrote:
>
> > For those who understand bonnie ( i don’t). This is a command line taken
> > from https://calomel.org/zfs_raid_speed_capacity.html.
> > I ran it on my zfspool.
> >
> > Version 1.97 ------Sequential Output------ --Sequential Input-
> > --Random-
> > Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
> > --Seeks--
> > Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
> /sec
> > %CP
> > Zolder-server 80G 318688 37 136544 25 269337 20
> > 38.6 2
> > Latency 4301ms 1176ms 549ms
> > 658ms
> >
>
> beware with Bonnie, more often than not (and that's certainly the case
> with the calomel review), due to the arguments provided what they are
> really testing is the cache and memory speed, and rarely the actual
> raw I/O to the disk.
>
> 136MB/s on 6 disks in RAIDZ2 is rather low, much lower than I would
> have expected (mine gives me over 400MB/s of raw I/O under similar
> conditions)
>
It's an "out of the box installation" from the zfs repository. Ran out of
time to understand and tune the parameters. But it worked, met the
requirements at the time.
Probably not a bad idea to see what can be tweaked. There is still a
possibility to move all data to the SSD or another disk and meanwhile
optimize the ZFS.
But it looks like ZFS is not my main bottleneck. Even at a poor 139MB/s it
manages to write 500GB per hour. (theoretically, and with reservations with
regards to the measurement method)
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