On Wed, Jun 23, 2021 at 9:59 AM Matthias Ferdinand <mf+ml.c...@mfedv.net> wrote:
>
> On Tue, Jun 22, 2021 at 02:36:00PM +0200, Ml Ml wrote:
> > Hello List,
> >
> > oversudden i can not mount a specific rbd device anymore:
> >
> > root@proxmox-backup:~# rbd map backup-proxmox/cluster5 -k
> > /etc/ceph/ceph.client.admin.keyring
> > /dev/rbd0
> >
> > root@proxmox-backup:~# mount /dev/rbd0 /mnt/backup-cluster5/
> > (just never times out)
>
>
> Hi,
>
> there used to be some kernel lock issues when the kernel rbd client
> tried to access an OSD on the same machine. Not sure if these issues
> still exist (but I would guess so) and if you use your proxmox cluster
> in a hyperconverged manner (nodes providing VMs and storage service at
> the same time) you may just have been lucky that it had worked before.
>
> Instead of the kernel client mount you can try to export the volume as
> an NBD device (https://docs.ceph.com/en/latest/man/8/rbd-nbd/) and
> mounting that. rbd-nbd runs in userspace and should not have that
> locking problem.
rbd-nbd is also susceptible to locking up in such setups, likely more
so than krbd. Don't forget that it also has a kernel component and
there are actually more opportunities for things to go sideways/lock up
because there is an extra daemon involved allocating some additional
memory for each I/O request.
Thanks,
Ilya
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