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.


[1] http://docs.ceph.com/docs/mimic/rados/operations/pools/#set-pool-values

On Tue, Sep 18, 2018 at 7:11 AM Frank Schilder <[email protected]> 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
> _______________________________________________
> ceph-users mailing list
> [email protected]
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
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