Re: poor data distribution

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On Thu, 30 Jan 2014, Dominik Mostowiec wrote:
> Hi,
> Thaks for Your response.
> 
> > - with ~6,5k objects,  size ~1,4G
> > - with ~13k objects, size ~2,8G
> is on one the biggest pool 5 '.rgw.buckets'
> 
> > This is because pg_num is not a power of 2
> This is for all PGs (sum of all pools) or for pool 5 '.rgw.buckets'
> where i have almost all data ?

Each pool's pg_num is ideally a power of 2.

> 
> > Did you try, ceph osd crush tunables optimal
> No, I'll try it after change pg_num to correct value.
> 
> --
> Regards
> Dominik
> 
> 
> 2014-01-30 Sage Weil <sage@xxxxxxxxxxx>:
> > On Thu, 30 Jan 2014, Dominik Mostowiec wrote:
> >> Hi,
> >> I found something else.
> >> 'ceph pg dump' shows PGs:
> >> - with zero or near zero objects count
> >
> > These are probably for a different pool than the big ones, right?  The
> > PG id is basically $pool.$shard.
> >
> >> - with ~6,5k objects,  size ~1,4G
> >> - with ~13k objects, size ~2,8G
> >> This can be a reason of wrong data distribution on OSD's?
> >
> > This is because pg_num is not a power of 2.  Generally that won't result
> > in an imbalance as drastic as yours, though.  If you do adjust pg_num,
> > bump it up to the power of 2.
> >
> > Did you try
> >
> >  ceph osd crush tunables optimal
> >
> > ?
> > sage
> >
> >
> >>
> >> ---
> >> Regards
> >> Dominik
> >>
> >>
> >> 2014-01-30 Dominik Mostowiec <dominikmostowiec@xxxxxxxxx>:
> >> > Hi,
> >> > I have problem with data distribution.
> >> > Smallest disk usage 40% vs highest 82%.
> >> > All PGS: 6504.
> >> > Almost all data is in '.rgw.buckets' pool with pg_num 4800.
> >> > The best way to better data distribution is increese pg_num in this pool?
> >> > Is thre another way? ( eg crush tunables, or something like that ..)
> >> >
> >> > Config: 9 hosts X 22 OSD = 198 OSDs
> >> > replica = 3
> >> >
> >> > ceph -v
> >> > ceph version 0.67.5 (a60ac9194718083a4b6a225fc17cad6096c69bd1)
> >> >
> >> > ceph osd dump:
> >> > pool 0 'data' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 64 pgp_num 64 last_change 28459 owner 0
> >> > crash_replay_interval 45
> >> > pool 1 'metadata' rep size 3 min_size 1 crush_ruleset 1 object_hash
> >> > rjenkins pg_num 64 pgp_num 64 last_change 28460 owner 0
> >> > pool 2 'rbd' rep size 3 min_size 1 crush_ruleset 2 object_hash
> >> > rjenkins pg_num 64 pgp_num 64 last_change 28461 owner 0
> >> > pool 3 '.rgw.buckets' rep size 3 min_size 1 crush_ruleset 0
> >> > object_hash rjenkins pg_num 4800 pgp_num 4800 last_change 28462 owner
> >> > 0
> >> > pool 4 '.log' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 1440 pgp_num 1440 last_change 28463 owner 0
> >> > pool 5 '.rgw' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 28464 owner 0
> >> > pool 6 '.users.uid' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 28465 owner 0
> >> > pool 7 '.users' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 28466 owner 0
> >> > pool 8 '.usage' rep size 2 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 28467 owner
> >> > 18446744073709551615
> >> > pool 9 '.intent-log' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 28468 owner
> >> > 18446744073709551615
> >> > pool 10 '.rgw.control' rep size 3 min_size 1 crush_ruleset 0
> >> > object_hash rjenkins pg_num 8 pgp_num 8 last_change 33485 owner
> >> > 18446744073709551615
> >> > pool 11 '.rgw.gc' rep size 3 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 33487 owner
> >> > 18446744073709551615
> >> > pool 12 '.rgw.root' rep size 2 min_size 1 crush_ruleset 0 object_hash
> >> > rjenkins pg_num 8 pgp_num 8 last_change 44540 owner 0
> >> > pool 13 '' rep size 2 min_size 1 crush_ruleset 0 object_hash rjenkins
> >> > pg_num 8 pgp_num 8 last_change 46912 owner 0
> >> >
> >> > rados df:
> >> > pool name       category                 KB      objects       clones
> >> >    degraded      unfound           rd        rd KB           wr
> >> > wr KB
> >> >                 -                          0            0            0
> >> >            0           0            0            0            0
> >> >     0
> >> > .intent-log     -                          0            0            0
> >> >            0           0            1            0      1893949
> >> > 1893697
> >> > .log            -                      69222         6587            0
> >> >            0           0            0            0    172911881
> >> > 172884792
> >> > .rgw            -                     114449       813564            0
> >> >            0           0     51094886     39834914      3606364
> >> > 1047115
> >> > .rgw.buckets    -                10371229682     54367877            0
> >> >            0           0   2610759046  54967451976   1930820947
> >> > 24031291524
> >> > ....
> >> > empty pools
> >> >
> >> > --
> >> > Regards
> >> > Dominik
> >>
> >>
> >>
> >> --
> >> Pozdrawiam
> >> Dominik
> >> _______________________________________________
> >> ceph-users mailing list
> >> ceph-users@xxxxxxxxxxxxxx
> >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >>
> >>
> 
> 
> 
> -- 
> Pozdrawiam
> Dominik
> 
> 
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