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

David Turner drakonstein at gmail.com
Fri Oct 12 07:50:31 PDT 2018


If you go down just a little farther you'll see the settings that you put
into your ceph.conf under the osd section (although I'd probably do
global).  That's where the OSDs get the settings from.  As a note, once
these are set, future writes will be compressed (if they match the
compression settings which you can see there about minimum ratios, blob
sizes, etc).  To compress current data, you need to re-write it.

On Fri, Oct 12, 2018 at 10:41 AM Frank Schilder <frans at dtu.dk> wrote:

> Hi David,
>
> thanks for your quick answer. When I look at both references, I see
> exactly the same commands:
>
> ceph osd pool set {pool-name} {key} {value}
>
> where on one page only keys specific for compression are described. This
> is the command I found and used. However, I can't see any compression
> happening. If you know about something else than "ceph osd pool set" -
> commands, please let me know.
>
> Best regards,
>
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: David Turner <drakonstein at gmail.com>
> Sent: 12 October 2018 15:47:20
> To: Frank Schilder
> Cc: ceph-users at lists.ceph.com
> Subject: Re: [ceph-users] bluestore compression enabled but no data
> compressed
>
> 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<mailto:
> 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<mailto:drakonstein at gmail.com>>
> Sent: 09 October 2018 17:42
> To: Frank Schilder
> Cc: ceph-users at lists.ceph.com<mailto: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><mailto: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><mailto:
> ceph-users at lists.ceph.com<mailto:ceph-users at lists.ceph.com>>
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20181012/2f67f9ec/attachment.html>


More information about the ceph-users mailing list