[DRBD-user] DRBD SAMBA (again) and NFS

Admin drbd-info at internode.com.au
Thu Jun 1 11:14:42 CEST 2006

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

nfs (udp-based nfs is stateless) - that means if the nfs serving node fails 
over, the clients access to that share will freeze briefly and then continue 
where they were (open files will remain open, programs executed from the 
filesystem will continue to run)

smb (the file sharing protocol which samba implements) is statefull - this 
means that if the samba server node fails over, the client may/will report an 
error (since the actual connection between the client and the server is 
broken - samba gets started on the second node but this will be a new 
connection which the client must issue a retry against). How this is handled 
is up to the client. There are no mainstream platforms which offer session 
failover for smb as far as i know - maybe vms clustering could work some 
magic but thats about it. Microsoft clustering of file shares has exactly the 
same problem.

the problem is not that the file will not be mirrored, but that the clients' 
connections to the server will break and need to be restarted/retried 
(manually or maybe automagically by the application). this may or may not  be 
visible to the user - it depends on the platform (windows version) and the 

it is necessary that the samba tdb files (which contain a record of client 
locks and other "stateful" information) be on the replicated disk, to ensure 
the second node can read them when it is failed over to. In a failover 
situation, I think these are somewhat analogous to the nfs server's rmtab 

you can share out the same directories via samba and nfs. be aware that your 
server platform may or may not synchronise locking between these two sharing 
technologies (linux and irix will, probably freebsd too). the configuration 
of the sharing of these directories will be maintained separately: nfs 
in /etc/exports, samba in /etc/smb.conf

the samba and nfs HA resources will both have the same disk resource 
associated with them (the drbd device in this case)

see the notes at the end of this page for more info:


On Thursday 01 June 2006 17:46, Philippe Rousselot wrote:
> Hello
> I want to make a samba HA system. The reason I do not use NFS  is the
> presence of a few windows machines in the network.
> I spent some time reading the archives and I have a few points to
> clarify.
> There are no problems having a NFS HA system using DRBD and heartbeat,
> but samba not being state-less there maybe some error during the
> mirroring.
> This error can be overcome by retrying.
> what do it mean ?
> someone save a file and it is not mirrored ?
> but it will be at some point ?
> do I need to survey the system and do something when there is an error
> or is there an automatic system that will solve the problem at some
> point ?
> is this error visible directly from the client under windows ?
> is it possible to have a system sharing NFS and Samba properties ? I
> have a folder and when I use a linux client I use samba ad when I use a
> windows client I use samba. as I have a NFS share, the problem is
> solved ?
> sorry if these question seems trivial.
> Thanks for you help
> Philippe
> --
> Philippe Rousselot <prousselot at alcatorda.com>

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