Oh, also because the compression is at the osd level you don't see it
in ceph df. You just see that your RAW is not increasing as much as
you'd expect. E.g.
$ sudo ceph df
GLOBAL:
SIZE AVAIL RAW USED %RAW USED
785T 300T 485T 61.73
POOLS:
NAME ID USED %USED MAX AVAIL OBJECTS
cephfs-metadata 11 185M 0 68692G 178
cephfs-data 12 408T 75.26 134T 132641159
You can see that we've used 408TB in the pool but only 485TB RAW -
Rather than ~600TB RAW that I'd expect for my k4, m2 pool settings.
On Fri, 29 Jun 2018 at 17:08, Richard Bade <hitrich@xxxxxxxxx> wrote:
>
> I'm using compression on a cephfs-data pool in luminous. I didn't do
> anything special
>
> $ sudo ceph osd pool get cephfs-data all | grep ^compression
> compression_mode: aggressive
> compression_algorithm: zlib
>
> You can check how much compression you're getting on the osd's
> $ for osd in `seq 0 11`; do echo osd.$osd; sudo ceph daemon osd.$osd
> perf dump | grep 'bluestore_compressed'; done
> osd.0
> "bluestore_compressed": 686487948225,
> "bluestore_compressed_allocated": 788659830784,
> "bluestore_compressed_original": 1660064620544,
> <snip>
> osd.11
> "bluestore_compressed": 700999601387,
> "bluestore_compressed_allocated": 808854355968,
> "bluestore_compressed_original": 1752045551616,
>
> I can't say for mimic, but definitely for luminous v12.2.5 compression
> is working well with mostly default options.
>
> -Rich
>
> > For RGW, compression works very well. We use rgw to store crash dumps, in
> > most cases, the compression ratio is about 2.0 ~ 4.0.
>
> > I tried to enable compression for cephfs data pool:
>
> > # ceph osd pool get cephfs_data all | grep ^compression
> > compression_mode: force
> > compression_algorithm: lz4
> > compression_required_ratio: 0.95
> > compression_max_blob_size: 4194304
> > compression_min_blob_size: 4096
>
> > (we built ceph packages and enabled lz4.)
>
> > It doesn't seem to work. I copied a 8.7GB folder to cephfs, ceph df says it
> > used 8.7GB:
>
> > root at ceph-admin:~# ceph df
> > GLOBAL:
> > SIZE AVAIL RAW USED %RAW USED
> > 16 TiB 16 TiB 111 GiB 0.69
> > POOLS:
> > NAME ID USED %USED MAX AVAIL OBJECTS
> > cephfs_data 1 8.7 GiB 0.17 5.0 TiB 360545
> > cephfs_metadata 2 221 MiB 0 5.0 TiB 77707
>
> > I know this folder can be compressed to ~4.0GB under zfs lz4 compression.
>
> > Am I missing anything? how to make cephfs compression work? is there any
> trick?
>
> > By the way, I am evaluating ceph mimic v13.2.0.
>
> > Thanks in advance,
> > --Youzhong
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