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 > >> _______________________________________________ > >> ceph-users mailing list -- ceph-users@xxxxxxx > >> To unsubscribe send an email to ceph-users-leave@xxxxxxx > >> _______________________________________________ > >> ceph-users mailing list -- ceph-users@xxxxxxx > >> To unsubscribe send an email to ceph-users-leave@xxxxxxx > >> > > _______________________________________________ > > ceph-users mailing list -- ceph-users@xxxxxxx > > To unsubscribe send an email to ceph-users-leave@xxxxxxx > > -- > Christophe BAILLON > Mobile :: +336 16 400 522 > Work :: https://eyona.com > Twitter :: https://twitter.com/ctof > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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