Yeah, I was really just curious if the proposed system was at a system level
or a network level. Having two physical machines share (at the system i/o
level) a storage unit is something I have never heard of. Does such a beast
exist? I assume other RDBMS's use replication to fulfill high-availability
From: Tony Simopoulos [mailto:karkalis(at)earthling(dot)net]
Sent: Monday, October 16, 2000 5:43 PM
To: Clark, Joel
Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> Through an NFS mount maybe?
without a "distributed lock manager" sharing cannot be done efficiently.
NFS creates problems both desired features of this set-up.
1) High Availability
if the computer that is serving the NFS mount goes down, any other machine
using the "share" goes down as well -- i.e. single-point
2) Load Balancing
NFS is extremely expensive. all that would be balanced is the database
logic; in place sorting, connection overheads, etc.
expensive reads and writes will all hit the NFS mounting server -- i.e.
single-threading every query to the disk i/o of one machine.
> -----Original Message-----
> From: Tony Simopoulos [mailto:karkalis(at)earthling(dot)net]
> Sent: Monday, October 16, 2000 3:03 PM
> To: Oscar Serrano
> Cc: pgsql-interfaces(at)postgresql(dot)org
> Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> a redundant, replicated, or parallel system (choose whichever adjective
> befits your desires) is being developed. check out
> sharing a single disk is an O/S & hardware problem. what is your intended
> good luck,
> ----- Original Message -----
> From: Oscar Serrano <oserra(at)fondos(dot)net>
> To: Postgres interfaces <pgsql-interfaces(at)postgresql(dot)org>
> Sent: Monday, October 16, 2000 2:15 PM
> Subject: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it possible?
> > Hi men :-)
> > Just one question for those of you who have spent many time with
> > I want to create a load balancing and High Availability system with two
> > servers.
> > This two server have a common hard disk: A RAID 5 server connected to
> > by the LAN.
> > I have a hardware machine (WSD+ from RADWARE) that manages the load
> > balancing.
> > I want to have, two servers, and two postgres installations, one in each
> > server, but with a common PGDATA directory in the RAID.
> > So, if one of the servers crashes, people can still get the information
> > the other server.
> > Esentially, what I want is, two postgres (one in each machine) with a
> > PGDATA directory, and that both postgres can access and do Inserts in
> > tables, and when one postgres does an insert, the second sees what the
> > has inserted.
> > Thanks.
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