Re: Stupid question about ceph fs volume

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Did you set the ec-overwrites flag for the pool as mentioned in the docs?
https://docs.ceph.com/en/latest/cephfs/createfs/#using-erasure-coded-pools-with-cephfs

If you plan to use pre-created pools anyway then the slightly more manual method is the way to go.
You can set the pg_num (and pgp_num) while you create a pool:

ceph:~ # ceph osd pool create testpool 16 16 replicated
pool 'testpool' created



Zitat von Albert Shih <Albert.Shih@xxxxxxxx>:

Le 25/01/2024 à 08:42:19+0000, Eugen Block a écrit
Hi,

it's really as easy as it sounds (fresh test cluster on 18.2.1 without any
pools yet):

ceph:~ # ceph fs volume create cephfs

Yes...I already try that with the label and works fine.

But I prefer to use «my» pools. Because I have ssd/hdd and want also try
«erasure coding» pool for the data.

I also need to set the pg_num and pgp_num (I know I can do that after the
creation).


So I manage to do ... half what I want...

In fact

  ceph fs volume create thing

will create two pools

  cephfs.thing.meta
  cephfs.thing.data

and if those pool already existe it will use them.

But that's only if the data are replicated no with erasure coding....(maybe
I forget something config on the pool).

Well I will currently continue my test with replicated data.

The pools and the daemons are created automatically (you can control the
placement of the daemons with the --placement option). Note that the
metadata pool needs to be on fast storage, so you might need to change the
ruleset for the metadata pool after creation in case you have HDDs in place.
Changing pools after the creation can be done via ceph fs commands:

ceph:~ # ceph osd pool create cephfs_data2
pool 'cephfs_data2' created

ceph:~ # ceph fs add_data_pool cephfs cephfs_data2
  Pool 'cephfs_data2' (id '4') has pg autoscale mode 'on' but is not marked
as bulk.
  Consider setting the flag by running
    # ceph osd pool set cephfs_data2 bulk true
added data pool 4 to fsmap

ceph:~ # ceph fs status
cephfs - 0 clients
======
RANK  STATE             MDS               ACTIVITY     DNS    INOS   DIRS
CAPS
 0    active  cephfs.soc9-ceph.uqcybj  Reqs:    0 /s    10     13     12

       POOL           TYPE     USED  AVAIL
cephfs.cephfs.meta  metadata  64.0k  13.8G
cephfs.cephfs.data    data       0   13.8G
   cephfs_data2       data       0   13.8G


You can't remove the default data pool, though (here it's
cephfs.cephfs.data). If you want to control the pool creation you can fall
back to the method you mentioned, create pools as you require them and then
create a new cephfs, and deploy the mds service.

Yes, but I'm guessing the

  ceph fs volume

are the «future» so it would be super nice to add (at least) the option to
choose the couple of pool...


I haven't looked too deep into changing the default pool yet, so there might
be a way to switch that as well.

Ok. I will also try but...well...newbie ;-)

Anyway thanks.

regards

--
Albert SHIH 🦫 🐸
France
Heure locale/Local time:
jeu. 25 janv. 2024 12:00:08 CET


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