Hi all,
I've noticed that objects are using twice their actual space for a few
minutes after they are 'put' via rados:
$ ceph -v
ceph version 0.79-42-g010dff1 (010dff12c38882238591bb042f8e497a1f7ba020)
$ ceph osd tree
# id weight type name up/down reweight
-1 0.03998 root default
-2 0.009995 host ceph1
0 0.009995 osd.0 up 1
-3 0.009995 host ceph2
1 0.009995 osd.1 up 1
-4 0.009995 host ceph3
2 0.009995 osd.2 up 1
-5 0.009995 host ceph4
3 0.009995 osd.3 up 1
$ ceph osd dump|grep repool
pool 5 'repool' replicated size 3 min_size 2 crush_ruleset 0 object_hash
rjenkins pg_num 64 pgp_num 64 last_change 57 owner 0 flags hashpspool
stripe_width 0
$ du -m file
1025 file
$ rados put -p repool file file
$ cd /var/lib/ceph/osd/ceph-1/current/
$ du -m 5.1a_head
2048 5.1a_head
[later]
$ du -m 5.1a_head
1024 5.1a_head
The above situation is repeated on the other two OSD's where this pg is
mapped. So after about 5 minutes or so we have (as expected) that the 1G
file is using 1G on each of the 3 OSD's it is mapped to, however for a
short period of time it is using twice this! I very interested to know
what activity is happening that causes the 2x space use - as this could
be a significant foot gun if uploading large files when we don't have 2x
the space available on each OSD.
Regards
Mark
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