Hi,
We were also affected by this bug when we deployed a new Pacific cluster.
Any news about the release of this fix to Ceph Pacific? It looks done
for Quincy version but not Pacific.
https://github.com/ceph/ceph/pull/47292
Regards,
Adrien
Le 05/10/2022 à 13:21, Anh Phan Tuan a écrit :
It seems the 17.2.4 release has fixed this.
ceph-volume: fix fast device alloc size on mulitple device (pr#47293,
Arthur Outhenin-Chalandre)
Bug #56031: batch compute a lower size than what it should be for blockdb
with multiple fast device - ceph-volume - Ceph
<https://tracker.ceph.com/issues/56031>
Regards,
Anh Phan
On Fri, Sep 16, 2022 at 2:34 AM Christophe BAILLON <cb@xxxxxxx> wrote:
Hi
The problem is still present in version 17.2.3,
thanks for the trick to work around...
Regards
----- Mail original -----
De: "Anh Phan Tuan" <anhphan.net@xxxxxxxxx>
À: "Calhoun, Patrick" <phineas@xxxxxx>
Cc: "Arthur Outhenin-Chalandre" <arthur.outhenin-chalandre@xxxxxxx>,
"ceph-users" <ceph-users@xxxxxxx>
Envoyé: Jeudi 11 Août 2022 10:14:17
Objet: Re: cephadm automatic sizing of WAL/DB on SSD
Hi Patrick,
I am also facing this bug when deploying a new cluster at the time 16.2.7
release.
The bugs relative to the way ceph calculator db_size form give db disk.
Instead of : slot db size = size of db disk / num slot per disk.
Ceph calculated the value: slot db size = size of db disk (just one
disk) /
total number of slots needed (number of osd prepared in that time).
In your case, you have 2 db disks, It will make the db size only 50% of
the
corrected value.
In my case, I have 4 db disks per host, It makes the db size only 25% of
the corrected value.
This bug happens even when you deploy by batch command.
In that time, I finally used to work around by batch command but only
deploy all osd relative to one db disk a time, in this case ceph
calculated
the correct value.
Cheers,
Anh Phan
On Sat, Jul 30, 2022 at 12:31 AM Calhoun, Patrick <phineas@xxxxxx>
wrote:
Thanks, Arthur,
I think you are right about that bug looking very similar to what I've
observed. I'll try to remember to update the list once the fix is merged
and released and I get a chance to test it.
I'm hoping somebody can comment on what are ceph's current best
practices
for sizing WAL/DB volumes, considering rocksdb levels and compaction.
-Patrick
________________________________
From: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@xxxxxxx>
Sent: Friday, July 29, 2022 2:11 AM
To: ceph-users@xxxxxxx <ceph-users@xxxxxxx>
Subject: Re: cephadm automatic sizing of WAL/DB on SSD
Hi Patrick,
On 7/28/22 16:22, Calhoun, Patrick wrote:
In a new OSD node with 24 hdd (16 TB each) and 2 ssd (1.44 TB each),
I'd
like to have "ceph orch" allocate WAL and DB on the ssd devices.
I use the following service spec:
spec:
data_devices:
rotational: 1
size: '14T:'
db_devices:
rotational: 0
size: '1T:'
db_slots: 12
This results in each OSD having a 60GB volume for WAL/DB, which
equates
to 50% total usage in the VG on each ssd, and 50% free.
I honestly don't know what size to expect, but exactly 50% of capacity
makes me suspect this is due to a bug:
https://tracker.ceph.com/issues/54541
(In fact, I had run into this bug when specifying block_db_size rather
than db_slots)
Questions:
Am I being bit by that bug?
Is there a better approach, in general, to my situation?
Are DB sizes still governed by the rocksdb tiering? (I thought that
this was mostly resolved by https://github.com/ceph/ceph/pull/29687 )
If I provision a DB/WAL logical volume size to 61GB, is that
effectively a 30GB database, and 30GB of extra room for compaction?
I don't use cephadm, but it's maybe related to this regression:
https://tracker.ceph.com/issues/56031. At list the symptoms looks very
similar...
Cheers,
--
Arthur Outhenin-Chalandre
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--
Christophe BAILLON
Mobile :: +336 16 400 522
Work :: https://eyona.com
Twitter :: https://twitter.com/ctof
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