[OmniOS-discuss] [discuss] background snapshot destruction impact
Tobias Oetiker
tobi at oetiker.ch
Mon Dec 23 07:56:58 UTC 2013
Hi Richard,
Yesterday Richard Elling wrote:
> On Dec 22, 2013, at 4:23 PM, Tobias Oetiker <tobi at oetiker.ch> wrote:
>
> > Hi Richard,
> >
> > Yesterday Richard Elling wrote:
> >
> >>> c) shouldn't the smarter write throttle change
> >>> https://github.com/illumos/illumos-gate/commit/69962b5647e4a8b9b14998733b765925381b727e
> >>> have helped with this by makeing zfs do its internal things
> >>> with a lower priority.
> >>
> >> Yes, but the default zfs_vdev_max_pending remains at 10. Once
> >> the I/Os are sent to disk, there is no priority scheduling. You
> >> should consider lowering zfs_vdev_max_pending to allow the ZIO
> >> scheduler to do a better job of rescheduling the more important
> >> I/Os.
> >
> > the patch mentioned introduces a ton of new tuneables but it
> > removes zfs_vdev_max_pending
>
> Indeed, these are now zfs_vdev_max_active and friends.
> It is very unclear to me what your graphite is attempting to show.
> Is this data from the pool itself, or from vdevs under the pool?
> The pool-level stats are mostly useless for this analysis, need to
> see the per-vdev stats.
the reason I am interested in this is that while the removal
operation is active, all data access to data not already in ARC
this is very slow ... 'ls' in a directory with 10 entries takes
several seconds to complete.
iostat -xnd 10 returns lines like this:
extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
85.3 265.1 350.4 3280.5 22.4 0.9 63.8 2.5 6 8 fast
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 rpool
0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5001517BB2AD9526d0
0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5001517BB2AD9589d0
0.0 92.8 0.0 1205.7 0.0 0.0 0.0 0.1 0 1 c0t5001517803D28EA3d0
0.6 331.8 0.4 789.1 0.0 1.4 0.0 4.2 0 99 c24t5000CCA03E45E11Dd0
11.1 25.6 49.9 302.8 0.0 0.1 0.0 3.2 0 5 c20t50014EE700052642d0
0.3 394.6 0.2 919.5 0.0 1.2 0.0 3.1 0 99 c25t5000CCA03E45E25Dd0
10.5 24.4 43.4 302.4 0.0 0.1 0.0 3.2 0 5 c19t50014EE70005217Ed0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c29t5000CCA03E404FDDd0
12.0 23.8 42.5 301.2 0.0 0.1 0.0 3.4 0 5 c15t50014EE70005248Ed0
0.4 427.3 0.3 960.5 0.0 1.7 0.0 3.9 0 99 c28t5000CCA03E426985d0
9.2 24.3 45.5 302.1 0.0 0.1 0.0 3.2 0 5 c18t50014EE7AAAFCC0Ad0
0.6 380.2 0.5 1061.0 0.0 1.8 0.0 4.6 0 99 c22t5000CCA03E45E211d0
11.1 24.8 49.1 301.2 0.0 0.1 0.0 3.0 0 5 c14t50014EE7555A792Ed0
0.4 330.6 0.3 800.3 0.0 1.3 0.0 3.9 0 99 c26t5000CCA03E420D4Dd0
10.4 24.7 35.8 302.7 0.0 0.1 0.0 2.6 0 4 c17t50014EE7555A7B7Ad0
0.6 371.7 0.5 901.7 0.0 1.2 0.0 3.1 0 99 c23t5000CCA03E434C41d0
10.4 27.3 52.0 302.1 0.0 0.1 0.0 3.1 0 5 c13t50014EE700052386d0
0.3 347.4 0.3 766.9 0.0 1.7 0.0 4.8 0 100 c27t5000CCA03E4229ADd0
10.6 24.2 32.3 301.3 0.0 0.1 0.0 2.8 0 5 c16t50014EE7555A7B4Ad0
3.2 2607.4 2.3 6539.9 3610203.4 10.2 1382912.3 3.9 100 100 slow
the config of the pool is this:
NAME STATE READ WRITE CKSUM
slowpool ONLINE 0 0 0
raidz2-0 ONLINE 0 0 0
c22t5000CCA03E45E211d0 ONLINE 0 0 0
c23t5000CCA03E434C41d0 ONLINE 0 0 0
c24t5000CCA03E45E11Dd0 ONLINE 0 0 0
c25t5000CCA03E45E25Dd0 ONLINE 0 0 0
c26t5000CCA03E420D4Dd0 ONLINE 0 0 0
c27t5000CCA03E4229ADd0 ONLINE 0 0 0
c28t5000CCA03E426985d0 ONLINE 0 0 0
logs
mirror-1 ONLINE 0 0 0
c0t5001517BB2AD9526d0s3 ONLINE 0 0 0
c0t5001517BB2AD9589d0s3 ONLINE 0 0 0
cache
c0t5001517803D28EA3d0s1 ONLINE 0 0 0
spares
c29t5000CCA03E404FDDd0 AVAIL
> ? richard
>
>
>
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--
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900
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