samba - Jan 2014 - gpfs + sernet samba + ctdb + transparent failover confusion

Hi all,

We're running gpfs 3.5.0.12 (5 total nsds & quorum servers, 2 nsds
running
samba), sernet-samba 4.1.4-7, and ctdb 1.0.114.7-1 and trying to get
transparent failover to work from a windows 8 client. We have ctdb failover
working, i.e. if I run mmshutdown on one of the nodes the IPs failover in a
few seconds after the GPFS mount is unmounted. For our transparent failover
test, I open up firefox and start downloading a large file, e.g. a centos
6.5 iso into the mapped network drive being served up by one of the samba
servers. Then I run an "mmshutdown" on the samba server the client is
connected to and as soon as the mount disappears on the server the download
stops and firefox throws an error. I was expecting that with transparent
failover that the download would "hang" until the IPs had a chance to
failover and the download/writes would continue but that didn't seem to
happen.

Any idea on how to get this to work? Do we need to use ctdb 2.5.1? What's
the difference between the sernet-samba provided ctdb 1.0.114 and the ctdb
2.5.1 line ? I tried to install the samba.org provided ctdb 2.5.1 RPMs but
it failed with :

ctdb >= 1.0.115 conflicts with sernet-samba-4.1.4-7.el6.x86_64

I also created rpm's using the spec file from the ctdb-2.5.1 sources and
got the same error. Looks like using "make install" would be the only
way
to get this installed, but even then why is sernet-samba requireing the
1.0.x line? Again, does it even matter with the original issue with
transparent failover?

Thanks,
Sabuj

After looking at this :

http://www.samba.org/~tridge/ctdb.pdf

It looks like this was working a long time ago with ctdb, winxp as a client
and without the need for protocol SMBv2 or even protocol v3.1 . So I'm
wondering if "disable that node" as mentioned in the pdf means
"service
ctdb stop" or loss of network connection and not "mmshutdown"
which yanks
the FS from underneath ctdb/samba? I'll give it a shot.


On Thu, Jan 23, 2014 at 4:19 PM, Sabuj Pattanayek <sabujp at gmail.com>
wrote:
> Hi all,
>
> We're running gpfs 3.5.0.12 (5 total nsds & quorum servers, 2 nsds
running
> samba), sernet-samba 4.1.4-7, and ctdb 1.0.114.7-1 and trying to get
> transparent failover to work from a windows 8 client. We have ctdb failover
> working, i.e. if I run mmshutdown on one of the nodes the IPs failover in a
> few seconds after the GPFS mount is unmounted. For our transparent failover
> test, I open up firefox and start downloading a large file, e.g. a centos
> 6.5 iso into the mapped network drive being served up by one of the samba
> servers. Then I run an "mmshutdown" on the samba server the
client is
> connected to and as soon as the mount disappears on the server the download
> stops and firefox throws an error. I was expecting that with transparent
> failover that the download would "hang" until the IPs had a
chance to
> failover and the download/writes would continue but that didn't seem to
> happen.
>
> Any idea on how to get this to work? Do we need to use ctdb 2.5.1?
What's
> the difference between the sernet-samba provided ctdb 1.0.114 and the ctdb
> 2.5.1 line ? I tried to install the samba.org provided ctdb 2.5.1 RPMs
> but it failed with :
>
> ctdb >= 1.0.115 conflicts with sernet-samba-4.1.4-7.el6.x86_64
>
> I also created rpm's using the spec file from the ctdb-2.5.1 sources
and
> got the same error. Looks like using "make install" would be the
only way
> to get this installed, but even then why is sernet-samba requireing the
> 1.0.x line? Again, does it even matter with the original issue with
> transparent failover?
>
> Thanks,
> Sabuj
>

Hi Sabuj,

SMB transparent failover is a new feature of SMB version 3.0
that is (cum grano salis) also known as Continuously Available
shares or persistent file handles.

This is a feature that is not yet implemented in Samba.
We are working on it, but there is a way to go...

Trigde's movies created the impression of a transparent
fail over, but this is in fact not the case: in those
demos, tride copied very small files in loop. After a
node failure, the client simply reconnected to a different
node (same IP), and potentially repeated the lost copy.
There were no long-running I/O ops involved.

The concept of durable file handles (from SMB2) can
provide transparent failover without interruption of I/O
in some cases. Durable file handles are implemented
starting with Samba 4.0. (See the manual page smb.conf
how to activate them.)

You won't get transparent fail over though if you kill
smbd or the node, though. If you do "ctdb disable" on
the active node though, you will see the I/O continuing
on the other node!

Cheers - Michael

On 2014-01-23 at 16:19 -0600, Sabuj Pattanayek wrote:
> Hi all,
> 
> We're running gpfs 3.5.0.12 (5 total nsds & quorum servers, 2 nsds
running
> samba), sernet-samba 4.1.4-7, and ctdb 1.0.114.7-1 and trying to get
> transparent failover to work from a windows 8 client. We have ctdb failover
> working, i.e. if I run mmshutdown on one of the nodes the IPs failover in a
> few seconds after the GPFS mount is unmounted. For our transparent failover
> test, I open up firefox and start downloading a large file, e.g. a centos
> 6.5 iso into the mapped network drive being served up by one of the samba
> servers. Then I run an "mmshutdown" on the samba server the
client is
> connected to and as soon as the mount disappears on the server the download
> stops and firefox throws an error. I was expecting that with transparent
> failover that the download would "hang" until the IPs had a
chance to
> failover and the download/writes would continue but that didn't seem to
> happen.
> 
> Any idea on how to get this to work? Do we need to use ctdb 2.5.1?
What's
> the difference between the sernet-samba provided ctdb 1.0.114 and the ctdb
> 2.5.1 line ? I tried to install the samba.org provided ctdb 2.5.1 RPMs but
> it failed with :
> 
> ctdb >= 1.0.115 conflicts with sernet-samba-4.1.4-7.el6.x86_64
> 
> I also created rpm's using the spec file from the ctdb-2.5.1 sources
and
> got the same error. Looks like using "make install" would be the
only way
> to get this installed, but even then why is sernet-samba requireing the
> 1.0.x line? Again, does it even matter with the original issue with
> transparent failover?
> 
> Thanks,
> Sabuj
> -- 
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> instructions:  https://lists.samba.org/mailman/options/samba
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