13 May
2020
13 May
'20
3:09 p.m.
Hi
On one of our Ceph clusters, some OSDs have been marked as full. Since this is a staging
cluster that does not have much data on it, this is strange.
Looking at the full OSDs through “ceph osd df” I figured out that the space is mostly used
by metadata:
SIZE: 122 GiB
USE: 118 GiB
DATA: 2.4 GiB
META: 116 GiB
We run mimic, and for the affected OSDs we use a db device (nvme) in addition to the
primary device (hdd).
In the logs we see the following errors:
2020-05-12 17:10:26.089 7f183f604700 1 bluefs _allocate failed to allocate 0x400000
on bdev 1, free 0x0; fallback to bdev 2
2020-05-12 17:10:27.113 7f183f604700 1 bluestore(/var/lib/ceph/osd/ceph-8)
_balance_bluefs_freespace gifting 0x180a000000~400000 to bluefs
2020-05-12 17:10:27.153 7f183f604700 1 bluefs add_block_extent bdev 2
0x180a000000~400000
We assume it is an issue with Rocksdb, as the following call will quickly fix the
problem:
ceph daemon osd.8 compact
The question is, why is this happening? I would think that “compact" is something
that runs automatically from time to time, but I’m not sure.
Is it on us to run this regularly?
Any pointers are welcome. I’m quite new to Ceph :)
Cheers,
Denis