Re: cephfs full, 2/3 Raw capacity used

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On 26-08-19 11:37, Dan van der Ster wrote:
Thanks. The version and balancer config look good.

So you can try `ceph osd reweight osd.10 0.8` to see if it helps to
get you out of this.

I've done this and the next fullest 3 osds. This will take some time to recover, I'll let you know when it's done.

Thanks,

/simon


-- dan

On Mon, Aug 26, 2019 at 11:35 AM Simon Oosthoek
<s.oosthoek@xxxxxxxxxxxxx> wrote:

On 26-08-19 11:16, Dan van der Ster wrote:
Hi,

Which version of ceph are you using? Which balancer mode?

Nautilus (14.2.2), balancer is in upmap mode.

The balancer score isn't a percent-error or anything humanly usable.
`ceph osd df tree` can better show you exactly which osds are
over/under utilized and by how much.


Aha, I ran this and sorted on the %full column:

   81   hdd   10.81149  1.00000  11 TiB 5.2 TiB 5.1 TiB   4 KiB  14 GiB
5.6 TiB 48.40 0.73  96     up                 osd.81
   48   hdd   10.81149  1.00000  11 TiB 5.3 TiB 5.2 TiB  15 KiB  14 GiB
5.5 TiB 49.08 0.74  95     up                 osd.48
154   hdd   10.81149  1.00000  11 TiB 5.5 TiB 5.4 TiB 2.6 GiB  15 GiB
5.3 TiB 50.95 0.76  96     up                 osd.154
129   hdd   10.81149  1.00000  11 TiB 5.5 TiB 5.4 TiB 5.1 GiB  16 GiB
5.3 TiB 51.33 0.77  96     up                 osd.129
   42   hdd   10.81149  1.00000  11 TiB 5.6 TiB 5.5 TiB 2.6 GiB  14 GiB
5.2 TiB 51.81 0.78  96     up                 osd.42
122   hdd   10.81149  1.00000  11 TiB 5.7 TiB 5.6 TiB  16 KiB  14 GiB
5.1 TiB 52.47 0.79  96     up                 osd.122
120   hdd   10.81149  1.00000  11 TiB 5.7 TiB 5.6 TiB 2.6 GiB  15 GiB
5.1 TiB 52.92 0.79  95     up                 osd.120
   96   hdd   10.81149  1.00000  11 TiB 5.8 TiB 5.7 TiB 2.6 GiB  15 GiB
5.0 TiB 53.58 0.80  96     up                 osd.96
   26   hdd   10.81149  1.00000  11 TiB 5.8 TiB 5.7 TiB  20 KiB  15 GiB
5.0 TiB 53.68 0.80  97     up                 osd.26
...
    6   hdd   10.81149  1.00000  11 TiB 8.3 TiB 8.2 TiB  88 KiB  18 GiB
2.5 TiB 77.14 1.16  96     up                 osd.6
   16   hdd   10.81149  1.00000  11 TiB 8.4 TiB 8.3 TiB  28 KiB  18 GiB
2.4 TiB 77.56 1.16  95     up                 osd.16
    0   hdd   10.81149  1.00000  11 TiB 8.6 TiB 8.4 TiB  48 KiB  17 GiB
2.2 TiB 79.24 1.19  96     up                 osd.0
144   hdd   10.81149  1.00000  11 TiB 8.6 TiB 8.5 TiB 2.6 GiB  18 GiB
2.2 TiB 79.57 1.19  95     up                 osd.144
136   hdd   10.81149  1.00000  11 TiB 8.6 TiB 8.5 TiB  48 KiB  17 GiB
2.2 TiB 79.60 1.19  95     up                 osd.136
   63   hdd   10.81149  1.00000  11 TiB 8.6 TiB 8.5 TiB 2.6 GiB  17 GiB
2.2 TiB 79.60 1.19  95     up                 osd.63
155   hdd   10.81149  1.00000  11 TiB 8.6 TiB 8.5 TiB   8 KiB  19 GiB
2.2 TiB 79.85 1.20  95     up                 osd.155
   89   hdd   10.81149  1.00000  11 TiB 8.7 TiB 8.5 TiB  12 KiB  20 GiB
2.2 TiB 80.04 1.20  96     up                 osd.89
106   hdd   10.81149  1.00000  11 TiB 8.8 TiB 8.7 TiB  64 KiB  19 GiB
2.0 TiB 81.38 1.22  96     up                 osd.106
   94   hdd   10.81149  1.00000  11 TiB 9.0 TiB 8.9 TiB     0 B  19 GiB
1.8 TiB 83.53 1.25  96     up                 osd.94
   33   hdd   10.81149  1.00000  11 TiB 9.1 TiB 9.0 TiB  44 KiB  19 GiB
1.7 TiB 84.40 1.27  96     up                 osd.33
   15   hdd   10.81149  1.00000  11 TiB  10 TiB 9.8 TiB  16 KiB  20 GiB
877 GiB 92.08 1.38  96     up                 osd.15
   53   hdd   10.81149  1.00000  11 TiB  10 TiB  10 TiB 2.6 GiB  20 GiB
676 GiB 93.90 1.41  96     up                 osd.53
   51   hdd   10.81149  1.00000  11 TiB  10 TiB  10 TiB 2.6 GiB  20 GiB
666 GiB 93.98 1.41  96     up                 osd.51
   10   hdd   10.81149  1.00000  11 TiB  10 TiB  10 TiB  40 KiB  22 GiB
552 GiB 95.01 1.42  97     up                 osd.10

So the fullest one is at 95.01%, the emptiest one at 48.4%, so there's
some balancing to be done.

You might be able to manually fix things by using `ceph osd reweight
...` on the most full osds to move data elsewhere.

I'll look into this, but I was hoping that the balancer module would
take care of this...


Otherwise, in general, its good to setup monitoring so you notice and
take action well before the osds fill up.

Yes, I'm still working on this, I want to add some checks to our
check_mk+icinga setup using native plugins, but my python skills are not
quite up to the task, at least, not yet ;-)

Cheers

/Simon


Cheers, Dan

On Mon, Aug 26, 2019 at 11:09 AM Simon Oosthoek
<s.oosthoek@xxxxxxxxxxxxx> wrote:

Hi all,

we're building up our experience with our ceph cluster before we take it
into production. I've now tried to fill up the cluster with cephfs,
which we plan to use for about 95% of all data on the cluster.

The cephfs pools are full when the cluster reports 67% raw capacity
used. There are 4 pools we use for cephfs data, 3-copy, 4-copy, EC 8+3
and EC 5+7. The balancer module is turned on and `ceph balancer eval`
gives `current cluster score 0.013255 (lower is better)`, so well within
the default 5% margin. Is there a setting we can tweak to increase the
usable RAW capacity to say 85% or 90%, or is this the most we can expect
to store on the cluster?

[root@cephmon1 ~]# ceph df
RAW STORAGE:
       CLASS     SIZE        AVAIL       USED        RAW USED     %RAW USED
       hdd       1.8 PiB     605 TiB     1.2 PiB      1.2 PiB         66.71
       TOTAL     1.8 PiB     605 TiB     1.2 PiB      1.2 PiB         66.71

POOLS:
       POOL                    ID     STORED      OBJECTS     USED
%USED      MAX AVAIL
       cephfs_data              1     111 MiB      79.26M     1.2 GiB
100.00           0 B
       cephfs_metadata          2      52 GiB       4.91M      52 GiB
100.00           0 B
       cephfs_data_4copy        3     106 TiB      46.36M     428 TiB
100.00           0 B
       cephfs_data_3copy        8      93 TiB      42.08M     282 TiB
100.00           0 B
       cephfs_data_ec83        13     106 TiB      50.11M     161 TiB
100.00           0 B
       rbd                     14      21 GiB       5.62k      63 GiB
100.00           0 B
       .rgw.root               15     1.2 KiB           4       1 MiB
100.00           0 B
       default.rgw.control     16         0 B           8         0 B
       0           0 B
       default.rgw.meta        17       765 B           4       1 MiB
100.00           0 B
       default.rgw.log         18         0 B         207         0 B
       0           0 B
       scbench                 19     133 GiB      34.14k     400 GiB
100.00           0 B
       cephfs_data_ec57        20     126 TiB      51.84M     320 TiB
100.00           0 B
[root@cephmon1 ~]# ceph balancer eval
current cluster score 0.013255 (lower is better)


Being full at 2/3 Raw used is a bit too "pretty" to be accidental, it
seems like this could be a parameter for cephfs, however, I couldn't
find anything like this in the documentation for Nautilus.


The logs in the dashboard show this:
2019-08-26 11:00:00.000630
[ERR]
overall HEALTH_ERR 3 backfillfull osd(s); 1 full osd(s); 12 pool(s) full

2019-08-26 10:57:44.539964
[INF]
Health check cleared: POOL_BACKFILLFULL (was: 12 pool(s) backfillfull)

2019-08-26 10:57:44.539944
[WRN]
Health check failed: 12 pool(s) full (POOL_FULL)

2019-08-26 10:57:44.539926
[ERR]
Health check failed: 1 full osd(s) (OSD_FULL)

2019-08-26 10:57:44.539899
[WRN]
Health check update: 3 backfillfull osd(s) (OSD_BACKFILLFULL)

2019-08-26 10:00:00.000088
[WRN]
overall HEALTH_WARN 4 backfillfull osd(s); 12 pool(s) backfillfull

So it seems that ceph is completely stuck at 2/3 full, while we
anticipated being able to fill up the cluster to at least 85-90% of the
raw capacity. Or at least so that we would keep a functioning cluster
when we have a single osd node fail.

Cheers

/Simon
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