samba - Aug 2016 - Samba with CTDB able to serve non-clustered data?

Hi Martin,

Thanks very much for the information.

I guess the part:

* Coherency of the file data you serve with Samba

  You need to make sure that updates to the data that you are serving
  are seen coherently across the cluster.

Is the tough one. Is there a way to do this that you know of when using NFS?

I see version 4.5 RC2 was just released. Do you know when it will be fully
released?

Thanks again,

Steve

On Wed, Aug 10, 2016 at 7:07 PM, Martin Schwenke <martin at meltin.net>
wrote:
> Hi Stephen,
>
> On Tue, 9 Aug 2016 18:08:15 -0400, Stephen Cousins via samba
> <samba at lists.samba.org> wrote:
>
> > I'd like to set up a HA Samba server that serves out data from NFS
> mounts​.
> > I was thinking that CTDB was the thing to do use but it is only
mentioned
> > with serving clustered file systems like Gluster, Lustre, etc. Is
there a
> > way to set up a HA Samba server without a clustered file system?
>
> You don't need a cluster filesystem to use CTDB.
>
> Cluster filesystems are mentioned in relation to CTDB for 2 reasons:
>
> * Coherency of the file data you serve with Samba
>
>   You need to make sure that updates to the data that you are serving
>   are seen coherently across the cluster.
>
> * Split brain protection
>
>   CTDB recommends using a recovery lock file in a cluster filesystem.
>   You don't have to use this but without it you aren't protected
>   against your cluster being partitioned (a.k.a. split brain).
>
>   From Samba >= 4.5, CTDB will support a configurable helper to handle
>   the recovery lock.
>
> If you can satisfy these requirements then you're good to go...  the
> important thing is to test... :-)
>
> The ping_pong tool can test a bunch of the necessary features:
>
>   https://wiki.samba.org/index.php/Ping_pong
>
> Good luck...
>
> peace & happiness,
> martin
>


-- 
________________________________________________________________
 Steve Cousins             Supercomputer Engineer/Administrator
 Advanced Computing Group            University of Maine System
 244 Neville Hall (UMS Data Center)              (207) 561-3574
 Orono ME 04469                      steve.cousins at maine.edu

Hi Steve,

On Thu, 11 Aug 2016 14:46:53 -0400, Stephen Cousins via samba
<samba at lists.samba.org> wrote:
> Thanks very much for the information.
> 
> I guess the part:
> 
> * Coherency of the file data you serve with Samba
> 
>   You need to make sure that updates to the data that you are serving
>   are seen coherently across the cluster.
> 
> Is the tough one. Is there a way to do this that you know of when using
NFS?
I don't have the NFS expertise to answer this.  Hopefully someone else
will step in with an answer...
> I see version 4.5 RC2 was just released. Do you know when it will be fully
> released?
The current plan is first half of September:

  https://wiki.samba.org/index.php/Release_Planning_for_Samba_4.5

peace & happiness,
martin

Hi,

Le 11 août 2016 22:04, "Martin Schwenke via samba" <samba at
lists.samba.org>
a écrit :
>
> Hi Steve,
>
> On Thu, 11 Aug 2016 14:46:53 -0400, Stephen Cousins via samba
> <samba at lists.samba.org> wrote:
>
> > Thanks very much for the information.
> >
> > I guess the part:
> >
> > * Coherency of the file data you serve with Samba
> >
> >   You need to make sure that updates to the data that you are serving
> >   are seen coherently across the cluster.
> >
> > Is the tough one. Is there a way to do this that you know of when
using
NFS?
>
> I don't have the NFS expertise to answer this.  Hopefully someone else
> will step in with an answer...
>
Although I wouldn't call myself an NFS expert, I already had to deal
similar setups.

NFS differs largely from distributed filesystem. It is a shared fs. Its
different nature makes consistency consideration less relevant than for
distributed filesystems.
Having said that, there are a couple of options you should set carefully.
Some on the NFS server, some others on the NFS client (here your samba
server).

- NFS Server options:
  > use synchronous exports (sync)

- NFS Clients options:
  > disable client cache when mounting the export (noac)
  > disable locks at Mount time (nolock)

Please note that the options above aim at providing reliable and consistent
data. They also have a performance impact and you should test how bad it
impacts your setup. This is a matter of trade-off.

Generally speaking, I wouldn't recommend re-sharing NFS exports. I always
had unexpected behaviors in this setup. Nfs not being posix compliant, be
prepared for some weird stuffs.

Regards.
> > I see version 4.5 RC2 was just released. Do you know when it will be
fully
> > released?
>
> The current plan is first half of September:
>
>   https://wiki.samba.org/index.php/Release_Planning_for_Samba_4.5
>
> peace & happiness,
> martin
>
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