[ceph-users] bluestore compression enabled but no data compressed

David Turner drakonstein at gmail.com
Fri Oct 12 06:47:20 PDT 2018


It's all of the settings that you found in your first email when you dumped
the configurations and such.
http://docs.ceph.com/docs/master/rados/configuration/bluestore-config-ref/#inline-compression

On Fri, Oct 12, 2018 at 7:36 AM Frank Schilder <frans at dtu.dk> wrote:

> Hi David,
>
> thanks for your answer. I did enable compression on the pools as described
> in the link you sent below (ceph osd pool set sr-fs-data-test
> compression_mode aggressive, I also tried force to no avail). However, I
> could not find anything on enabling compression per OSD. Could you possibly
> provide a source or sample commands?
>
> Thanks and best regards,
>
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: David Turner <drakonstein at gmail.com>
> Sent: 09 October 2018 17:42
> To: Frank Schilder
> Cc: ceph-users at lists.ceph.com
> Subject: Re: [ceph-users] bluestore compression enabled but no data
> compressed
>
> 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 <frans at dtu.dk<mailto:
> frans at dtu.dk>> 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 at ceph-01 ~]# ceph --version
> ceph version 12.2.7 (3ec878d1e53e1aeb47a9f619c49d9e7c0aa384d5) luminous
> (stable)
>
> All defaults are OK:
>
> [root at 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 at 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 at ceph-01 ~]# ceph osd pool get sr-fs-data-test compression_mode
> compression_mode: aggressive
> [root at 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 at 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 at 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 at ceph-01 ~]# rados ls -p sr-fs-data-test
> 10000000004.0000039c
> [...]
> 10000000004.0000039f
>
> It is 4M chunks ...
> [root at 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 at ceph-01 ~]# rados -p sr-fs-data-test get 10000000004.0000039f obj
>
> [root at 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
> ceph-users at lists.ceph.com<mailto:ceph-users at lists.ceph.com>
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