Coda File System

Re: Configuration for replicating servers

From: Phil Nelson <phil_at_merlin.cs.wwu.edu>
Date: Tue, 4 Jul 2000 11:22:24 -0700 (PDT)
>- Make two new entries in the /vice/db/VSGDB file. One for your new server
>  by itself, one of the form: E0000104 scm-server second-server. 
>I don't understand the 'One for your new server by itself' part here.
>I don't know what volume address to use, as my 2nd server does not have
>a root-volume of its own. Do I have to use the volume address of the
>root of the SCM? Or do I have to use a fake number?

The VSGDB defines "volume storage groups".  When volumes are created
via "createvol_rep", you specify a volume storage group, by number, for
where the volume is to be stored.  The numbers appear to be arbitrary (now)
but have historically started with E.......  Given your srv1 and srv2,
your VSGDB file might look like:

	E0000100 srv1
	E0000101 srv2
	E0000102 srv1 srv2

Now, when you create a volume, if you specify E0000102 as the storage group,
the volume will be replicated on srv1 and srv2.  If you choose E0000101, the
new volume will be stored only on srv2.  The client configuration does not
specify where volumes are stored, only the VSGDB.


>I also noticed that I cannot configure two clients to use the two
>servers of one cell. When I start to pump data into the cell with 
>cp -a /home/guido /coda/home/guido, the scm crashes and refuses to start up. 
>Is this expected behaviour?

To help you here, we need some server logs.  I suspect that you have
run into a bug that has plagued me for some time ... a volume with
only one replica (that is stored only on one server) is running out of
room in the resolution log.  If this is the case, one possible fix is
to turn off resolution for volumes with only one replica.  You can do
this by starting the server (without a client running) and when it is
up, use "volutil setlogparms <volumeid> reson 0".  Once that is
successful, then you can restart your clients and things should not
crash the server.  

In any case, don't turn off resolution for volumes that have multiple
replicas.


-- 
Phil Nelson                    NetBSD: http://www.netbsd.org
e-mail: phil@cs.wwu.edu        Coda: http://www.coda.cs.cmu.edu
http://www.cs.wwu.edu/~phil    
Received on 2000-07-04 14:38:23