When I've tested compression before there are 2 places you need to configure compression. On the OSDs in the configuration settings that you mentioned, but also on the [1] pools themselves. If you have the compression mode on the pools set to none, then it doesn't matter what the OSDs configuration is and vice versa unless you are using the setting of force. If you want to default compress everything, set pools to passive and osds to aggressive. If you want to only compress specific pools, set the osds to passive and the specific pools to aggressive. Good luck.
On Tue, Sep 18, 2018 at 7:11 AM Frank Schilder <frans@xxxxxx> wrote:
I seem to have a problem getting bluestore compression to do anything. I followed the documentation and enabled bluestore compression on various pools by executing "ceph osd pool set <pool-name> compression_mode aggressive". Unfortunately, it seems like no data is compressed at all. As an example, below is some diagnostic output for a data pool used by a cephfs:
[root@ceph-01 ~]# ceph --version
ceph version 12.2.7 (3ec878d1e53e1aeb47a9f619c49d9e7c0aa384d5) luminous (stable)
All defaults are OK:
[root@ceph-01 ~]# ceph --show-config | grep compression
[...]
bluestore_compression_algorithm = snappy
bluestore_compression_max_blob_size = 0
bluestore_compression_max_blob_size_hdd = 524288
bluestore_compression_max_blob_size_ssd = 65536
bluestore_compression_min_blob_size = 0
bluestore_compression_min_blob_size_hdd = 131072
bluestore_compression_min_blob_size_ssd = 8192
bluestore_compression_mode = none
bluestore_compression_required_ratio = 0.875000
[...]
Compression is reported as enabled:
[root@ceph-01 ~]# ceph osd pool ls detail
[...]
pool 24 'sr-fs-data-test' erasure size 8 min_size 7 crush_rule 10 object_hash rjenkins pg_num 50 pgp_num 50 last_change 7726 flags hashpspool,ec_overwrites stripe_width 24576 compression_algorithm snappy compression_mode aggressive application cephfs
[...]
[root@ceph-01 ~]# ceph osd pool get sr-fs-data-test compression_mode
compression_mode: aggressive
[root@ceph-01 ~]# ceph osd pool get sr-fs-data-test compression_algorithm
compression_algorithm: snappy
We dumped a 4Gib file with dd from /dev/zero. Should be easy to compress with excellent ratio. Search for a PG:
[root@ceph-01 ~]# ceph pg ls-by-pool sr-fs-data-test
PG_STAT OBJECTS MISSING_ON_PRIMARY DEGRADED MISPLACED UNFOUND BYTES LOG DISK_LOG STATE STATE_STAMP VERSION REPORTED UP UP_PRIMARY ACTING ACTING_PRIMARY LAST_SCRUB SCRUB_STAMP LAST_DEEP_SCRUB DEEP_SCRUB_STAMP
24.0 15 0 0 0 0 62914560 77 77 active+clean 2018-09-14 01:07:14.593007 7698'77 7735:142 [53,47,36,30,14,55,57,5] 53 [53,47,36,30,14,55,57,5] 53 7698'77 2018-09-14 01:07:14.592966 0'0 2018-09-11 08:06:29.309010
There is about 250MB data on the primary OSD, but noting seems to be compressed:
[root@ceph-07 ~]# ceph daemon osd.53 perf dump | grep blue
[...]
"bluestore_allocated": 313917440,
"bluestore_stored": 264362803,
"bluestore_compressed": 0,
"bluestore_compressed_allocated": 0,
"bluestore_compressed_original": 0,
[...]
Just to make sure, I checked one of the objects' contents:
[root@ceph-01 ~]# rados ls -p sr-fs-data-test
10000000004.0000039c
[...]
10000000004.0000039f
It is 4M chunks ...
[root@ceph-01 ~]# rados -p sr-fs-data-test stat 10000000004.0000039f
sr-fs-data-test/10000000004.0000039f mtime 2018-09-11 14:39:38.000000, size 4194304
... with all zeros:
[root@ceph-01 ~]# rados -p sr-fs-data-test get 10000000004.0000039f obj
[root@ceph-01 ~]# hexdump -C obj
00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00400000
All as it should be, except for compression. Am I overlooking something?
Best regards,
=================
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
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