[Samba] Re: samba Digest, Vol 45, Issue 18

William Marshall bmarsh at us.ibm.com
Fri Sep 15 16:50:00 GMT 2006

David Bear <David.Bear at asu.edu> wrote :

> I have read through some of the info on using dfs roots and I am
> needing some advice. Since a unc is still \\servername\ based it
> occurs to me that the only way to do this properly is to create a
> smb.conf file that publishes a netbios name like \\dfsroot -- Then, to
> create a failover system, I would take that config file and copy it
> around to multiple samba server. Then, have some kind of watch or
> heartbeat like monitor (that would only monitor where the name and
> services called \\dfsroot was still alive and responding) that would
> wait untill \\dfsroot no longer responded (where ever it was). Then,
> if \\dfsroot failed to respond, it new \\dfsroot smbserver would be
> launched to take over. 
> Conceptually, the smb service that is known as \\dfsroot really is
> just a 'share directory service'. It doesn't have to have any other
> shares that it serves. It could be guest readable.

You got it! If you have significant users mapping through \\dfsroot, you 
want a high availiabilty setup.

We have \\dfs1 & \\dfs2 that are "frontended" with a old network load 
balancer. We're about to move to sles 10 w/ Linux Virtual Server and Linux 
HA. The name we tell the users - \\dfs is registered in WINS & DNS to 
point to the IP of the load balancer.

Our code that creates the dfs symlinks makes the links on dfs1 & dfs2 -- 
you could also rsync regularly, etc. Very infrequently we have a problem 
with the 2 systems linking to different places.

If you want to use a something closer to your model you can use smbclient 
to probe \\dfsroot and then startup your backup system on a failure.

If I remember right you could have \\dfsroot guest readable -- however I 
think users would not get a bad password error on the "net use" and get 
confused. They would be into the dfs server as guest, but then fail to map 
to the final server if they used a bad password.

Hopefully your users are signed on to the desktops w/ domain userids. 
We've found that net use \\dfs\home\userid /user:different doesn't work 
well because winxp will connect to \\dfs as "different" but then goes back 
to the default (logged on) userid on the dfs redirect. 

Bill Marshall
Integrated Technology Delivery, Server Operations
Rochester PC Server Team
Rochester, MN

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