[PVE-User] Bluestore : Where is my WAL device ?

[Ronny Aasen]

on bluestore there is no journal. so i am very unsure about what 
--journal_dev  does in that context. probably nothing...

WAL is normally a part of the DB. and unless you have 3 tiers of speeds 
of drives there is no need to split the WAL away from the DB

since you specified the wal_dev and not the db_dev i think ceph was 
clever enough to understand that you actually wanted to put the db on 
sde1 and as you obsere with your symlinks, you can see it placed DB (and 
db's wal) on sde1


if you had osd spinner on sda, ssd DB on sde1  a even faster WAL nvme 
you could split wal from db by specifying --db_dev /dev/sde1 --wal_dev 
/dev/nvme1p1

but since you want wal and db on the same speed device (sde) there is no 
reason to split wal from db and just do
pveceph createosd /dev/sda --db_dev /dev/sde1


kind regards
Ronny Aasen





On 05.06.2018 15:49, rafael.diazmaurin at univ-rennes1.fr wrote:
> Hello,
>
> I run proxmox 5.2 with ceph 12.2 (bluestore).
>
> I've created an OSD on a Hard Drive (/dev/sda) and tried to put both 
> WAL and Journal on a SSD part (/dev/sde1) like this :
> pveceph createosd /dev/sda --wal_dev /dev/sde1 --journal_dev /dev/sde1
>
> It automaticaly creates 2 parts on the Hard Drive /dev/sda (the first 
> one /dev/sda1 called Ceph data and a 2nd one /dev/sda2 called Ceph 
> block).
>
> My problem is when I browse the OSD (/var/lib/ceph/osd/ceph-0/) I 
> can't find the symlink to the WAL device.
> -I see a symlink to the block.db (journal on /dev/sde1 as expected)
> -and another symlink to block that points to Hard Drive /dev/sda2 
> (by-partuuid)
> -but no block.wal at all...
>
>
> Can you explain me how to verify if the WAL device a really on the 
> /dev/sde1 ?
> And if not, how to put the WAL and the journal on the same SSD part.
>
>
> Many thanks,
> Rafael
>