Re: config files & bdb's in nfs

[Matti Aarnio <mea@nic.funet.fi>]

On Mon, Dec 22, 2003 at 05:20:11PM -0300, Mariano Absatz wrote:
> Hi there...
> 
> Is it possible, reasonable, advisable, to have zmailer's configuration 
> files (including BerkeleyDBs for routing, policy, etc.) in an NFS server?

Do refresh your memory about ZMailer's reference variables:
  http://zmailer.org/zman/zins-sysconfig.shtml#ZINS-RTF-ZMAILER.CONF

   "Software binaries, and databases: $MAILVAR/ (node local db's), 
    $MAILSHARE/ (site shared), $MAILBIN/ (read-only, site shared)"

(hmm.. something wrong here..  reading the SGML.. 
 No, just my reading, and a bit ordering that..)
After a bit of editing:

   "Software binaries, and databases: $MAILBIN/  (site shared, read-only), 
    $MAILSHARE/ (site shared, read-only), $MAILVAR/ (node local db's, r/w)"

The binary databases can be run in NFS-mounted setups to an extent
(NDBM, GDBM, Berkeley DB 1.x, at least),  and shared memory gimmics
in SleepyCat DB should not even be attempted in such..

Sharing  dbases.conf  shouldn't be all that challening.  Running
'zmailer newdb'  must be reserved to the master location of $MAILVAR/db/
directory.  Otherwise things should be quite simple -- as long as
all db usage instances are marked read-only...    Hmm..  They are,
by implication.

One way is to use some well known remote databases, like LDAP.
(Although that has its limits, too..)


Another approach with SleepyCat DB is to use its RPC support, although
that support isn't coded into present btree/bhash codes.
(Into  lib/sleepycatdb.c  to be exact...)

Related thing with SleepyCat is rather recent addition, but which
I do consider best approach:
   http://www.sleepycat.com/docs/ref/rep/intro.html#2
but that isn't supported in ZMailer either..  Could a SleepyCat 
replication utility be written, and included into ZMailer ?
Oh yes!

You update the master thru its keeper program, and it replicates
automagically to all replicas, and with replicas running in CDB-
mode, ZMailer can use them live.  ... I am not sure of all details
and usage models, nor I have time now to cook it up (although I
have written similar server in the past...)

> (I'm not talking about queues... /postoffice would be in a local disk).
> 
> I have to configure and keep in sync a bunch of identical balanced 
> servers, and I'm trying to minimize remote copies and commands...
> 
> TIA.
> --
> Mariano Absatz
> El Baby

-- 
/Matti Aarnio	<mea@nic.funet.fi>
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