[DRBD-user] SAMBA 3.0.9 writes surviving failover?

Philipp Reisner philipp.reisner at linbit.com
Wed Nov 24 10:53:53 CET 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Tuesday 23 November 2004 22:21, Musard, Kris wrote:
> I am working on a clustered fileserver using RedHat 9 + Heartbeat + DRBD
> 0.7.5 + Samba 3.0.9.  I have been able to setup NFS and AFS fileservices so
> that a file copy survives a failover and the file is not corrupted
> (verified with cksum).  Is this possible with Samba?  So far when I
> failover during the file copy through Samba I get the following error:

In the case of NFS, this is possible because NFS has this stateless protocol
(From my point of view a genial design decission of the initail NFS autors.)

What do you mean by AFS ? Apple File Sharing ? apfs ?

> "Cannot copy <filename>:an unexpected network error occurred"
> I only miss 1-2 pings during the failover.  I have my drbd mirrored
> directory as /smb and have linked /var/lib/samba and /etc/samba to
> /smb/varlibsamba and /smb/samba.  In my smb.conf file I have the locks and
> logs directories set to /smb/locks and /smb/logs respectively.  I have my
> service address on a dedicated ethernet interface and am failing over the
> MAC address along with the IP.  I have set the smb.conf file to restrict to
> this interface.  Any assistance would be appreciated.

The SMB protocol is not state-less, it relies on retries. But the nice thing
is that the client tells you that there was an error. So you have to retry.

Awkward would be it the SMB client would not tell you that it failed...

BTW, so achiev seamless SMB failover we would need to be able to migrate
open sockets. Werner Almesberger is working on this toppic. [He gave a 
speech about it on the last Linux Kongress.]

Conclusio: Today it is not possible to do SMB failover without retry.

Note: If the failover happens while no file is in flight, the client
      will not notice the failover, because there are some retry
      mechanism in Window's SMB client implementation.

: Dipl-Ing Philipp Reisner                      Tel +43-1-8178292-50 :
: LINBIT Information Technologies GmbH          Fax +43-1-8178292-82 :
: Schönbrunnerstr 244, 1120 Vienna, Austria    http://www.linbit.com :

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