Re: inline_data (was: CephFS and many small files)

[Clausen, Jörn <jclausen@xxxxxxxxx>]

Hi!

Am 29.03.2019 um 23:56 schrieb Paul Emmerich:
> There's also some metadata overhead etc. You might want to consider
> enabling inline data in cephfs to handle small files in a
> store-efficient way (note that this feature is officially marked as
> experimental, though).
> http://docs.ceph.com/docs/master/cephfs/experimental-features/#inline-data

Is there something missing from the documentation? I have turned on this 
feature:

$ ceph fs dump | grep inline_data
dumped fsmap epoch 1224
inline_data     enabled

I have reduced the size of the bonnie-generated files to 1 byte. But 
this is the situation halfway into the test: (output slightly shortened)

$ rados df
POOL_NAME      USED OBJECTS CLONES   COPIES
fs-data     3.2 MiB 3390041      0 10170123
fs-metadata 772 MiB    2249      0     6747

total_objects    3392290
total_used       643 GiB
total_avail      957 GiB
total_space      1.6 TiB

i.e. bonnie has created a little over 3 million files, for which the 
same number of objects was created in the data pool. So the raw usage is 
again at more than 500 GB.

If the data was inlined, I would expect far less objects in the data 
pool - actually none at all - and maybe some more usage in the metadata 
pool.

Do I have to restart any daemons after turning on inline_data? Am I 
missing anything else here?

For the record:

$ ceph versions
{
    "mon": {
        "ceph version 14.2.0 (3a54b2b6d167d4a2a19e003a705696d4fe619afc) 
nautilus (stable)": 3
    },
    "mgr": {
        "ceph version 14.2.0 (3a54b2b6d167d4a2a19e003a705696d4fe619afc) 
nautilus (stable)": 3
    },
    "osd": {
        "ceph version 14.2.0 (3a54b2b6d167d4a2a19e003a705696d4fe619afc) 
nautilus (stable)": 16
    },
    "mds": {
        "ceph version 14.2.0 (3a54b2b6d167d4a2a19e003a705696d4fe619afc) 
nautilus (stable)": 2
    },
    "overall": {
        "ceph version 14.2.0 (3a54b2b6d167d4a2a19e003a705696d4fe619afc) 
nautilus (stable)": 24
    }
}

--
Jörn Clausen
Daten- und Rechenzentrum
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
Düsternbrookerweg 20
24105 Kiel

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