samba - Feb 2003 - samba in a High Availability Configuration

Hello,

I'm sorry to post High availability oriented questions to this list, but
I was wondering about some samba configuration parameters and what
options are available.

I am using heartbeat, and to make a long story short, i have a floating
IP alias between 2 servers. (192.168.1.1 for example).  When one server
is serving the data, it 'has' this ip. if the server fails over, the
other machine takes over the IP alias address, and starts samba.

In order to make this work correctly, i have to use the 'interfaces'
smb.conf option, which sets smbd to listen to only certain ip addresses.

I also have bind interfaces only option on, which is required to prevent
two simultaneous smbd processes from binding to the same interface IP.

What I am interested in, is seamless failover, completely hidden from
the client in the middle of a copy.. Hopefully, they would only see a
stall in the copy..

Currently though, I get failed file operations because of the bind
interfaces only option.

the Bind interfaces only option requires that the 'interface' ip be
'UP'
in order for samba to start correctly. This causes problems because to
bring the IP address 'UP' before starting the samba server means that
the client sees that there is no server processing requests on the ip
for a small amount of time, which results in a failed operation.

I wonder if there is a way to have samba bind only to certain IP
addresses, but not require those addresses to be live at startup.


Thanks for all your work in the Open Source community, 

-- 
Matt Schillinger
mschilli@vss.fsi.com

On 18 Feb 2003, Matt Schillinger <mschilli@vss.fsi.com> wrote:
> I'm sorry to post High availability oriented questions to this list,
but
> I was wondering about some samba configuration parameters and what
> options are available.
You're welcome, this is on-topic here.
> What I am interested in, is seamless failover, completely hidden from
> the client in the middle of a copy.. Hopefully, they would only see a
> stall in the copy..
My understanding is that this is very hard (or impossible) to do at
the moment.  There is a lot of complicated statefulness in the CIFS
protocol (unlike, say, NFS) and so switching to another server in the
middle of an operation would, at the least, require a great deal of
new development work in Samba.  

There would need to be some kind of shared storage between the two
machines holding everything the server needs to know about active
connections.  This would be much deeper than just what's in the tdbs.
Perhaps somebody more experienced can give more details.

The best you can do is allow that connection to fail and then for the
client to reconnect.

-- 
Martin