Re: Fwd: NAS solution for CephFS

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On Thu, Feb 14, 2019 at 8:09 AM Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote:
>
> > Hi,
> > As http://docs.ceph.com/docs/master/cephfs/nfs/ says, it's OK to
> > config active/passive NFS-Ganesha to use CephFs. My question is if we
> > can use active/active nfs-ganesha for CephFS.
>
> (Apologies if you get two copies of this. I sent an earlier one from the
> wrong account and it got stuck in moderation)
>
> You can, with the new rados-cluster recovery backend that went into
> ganesha v2.7. See here for a bit more detail:
>
> https://jtlayton.wordpress.com/2018/12/10/deploying-an-active-active-nfs-cluster-over-cephfs/
>
> ...also have a look at the ceph.conf file in the ganesha sources.
>
> > In my thought, only state consistance should we think about.
> > 1. Lock support for Active/Active. Even each nfs-ganesha sever mantain
> > the lock state, the real lock/unlock will call
> > ceph_ll_getlk/ceph_ll_setlk. So Ceph cluster will handle the lock
> > safely.
> > 2. Delegation support Active/Active. It's similar question 1,
> > ceph_ll_delegation will handle it safely.
> > 3. Nfs-ganesha cache support Active/Active. As
> > https://github.com/nfs-ganesha/nfs-ganesha/blob/next/src/config_samples/ceph.conf
> > describes, we can config cache size as size 1.
> > 4. Ceph-FSAL cache support Active/Active. Like other CephFs client,
> > there is no issues for cache consistance.
>
> The basic idea with the new recovery backend is to have the different
> NFS ganesha heads coordinate their recovery grace periods to prevent
> stateful conflicts.
>
> The one thing missing at this point is delegations in an active/active
> configuration, but that's mainly because of the synchronous nature of
> libcephfs. We have a potential fix for that problem but it requires work
> in libcephfs that is not yet done.
[marvin] So we should disable delegation on active/active and set the
conf like this. Is it right?
NFSv4
{
Delegations = false;
}
>
> Cheers,
> --
> Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
>
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