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* 2 computers 1hd 2 postgres daemons. Is it possible?
@ 2000-10-16 18:15 Oscar Serrano <oserra@fondos.net>
2000-10-16 19:03 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Tony Simopoulos <karkalis@earthling.net>
0 siblings, 1 reply; 15+ messages in thread
From: Oscar Serrano @ 2000-10-16 18:15 UTC (permalink / raw)
To: pgsql-interfaces
Hi men :-)
Just one question for those of you who have spent many time with postgres.
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 them
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 from
the other server.
Esentially, what I want is, two postgres (one in each machine) with a shared
PGDATA directory, and that both postgres can access and do Inserts in the
tables, and when one postgres does an insert, the second sees what the first
has inserted.
Thanks.
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 18:15 2 computers 1hd 2 postgres daemons. Is it possible? Oscar Serrano <oserra@fondos.net>
@ 2000-10-16 19:03 ` Tony Simopoulos <karkalis@earthling.net>
0 siblings, 0 replies; 15+ messages in thread
From: Tony Simopoulos @ 2000-10-16 19:03 UTC (permalink / raw)
To: Oscar Serrano <oserra@fondos.net>; +Cc: pgsql-interfaces
a redundant, replicated, or parallel system (choose whichever adjective befits your desires) is being developed. check out
http://www.erserver.com/.
sharing a single disk is an O/S & hardware problem. what is your intended platform?
good luck,
tonys.
----- Original Message -----
From: Oscar Serrano <oserra@fondos.net>
To: Postgres interfaces <pgsql-interfaces@postgresql.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 postgres.
> 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 them
> 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 from
> the other server.
> Esentially, what I want is, two postgres (one in each machine) with a shared
> PGDATA directory, and that both postgres can access and do Inserts in the
> tables, and when one postgres does an insert, the second sees what the first
> has inserted.
>
> Thanks.
>
>
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* RE: 2 computers 1hd 2 postgres daemons. Is it possib le?
@ 2000-10-16 20:58 Clark, Joel <jclark@lendingtree.com>
2000-10-16 21:42 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Tony Simopoulos <karkalis@earthling.net>
2000-10-17 17:20 ` RE: 2 computers 1hd 2 postgres daemons. Is it possible? Oscar Serrano <oserra@fondos.net>
0 siblings, 2 replies; 15+ messages in thread
From: Clark, Joel @ 2000-10-16 20:58 UTC (permalink / raw)
To: 'Tony Simopoulos' <karkalis@earthling.net>; Oscar Serrano <oserra@fondos.net>; +Cc: pgsql-interfaces
Through an NFS mount maybe?
-----Original Message-----
From: Tony Simopoulos [mailto:karkalis@earthling.net]
Sent: Monday, October 16, 2000 3:03 PM
To: Oscar Serrano
Cc: pgsql-interfaces@postgresql.org
Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?
a redundant, replicated, or parallel system (choose whichever adjective
befits your desires) is being developed. check out
http://www.erserver.com/.
sharing a single disk is an O/S & hardware problem. what is your intended
platform?
good luck,
tonys.
----- Original Message -----
From: Oscar Serrano <oserra@fondos.net>
To: Postgres interfaces <pgsql-interfaces@postgresql.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 postgres.
> 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 them
> 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
from
> the other server.
> Esentially, what I want is, two postgres (one in each machine) with a
shared
> PGDATA directory, and that both postgres can access and do Inserts in the
> tables, and when one postgres does an insert, the second sees what the
first
> has inserted.
>
> Thanks.
>
>
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 20:58 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
@ 2000-10-16 21:42 ` Tony Simopoulos <karkalis@earthling.net>
1 sibling, 0 replies; 15+ messages in thread
From: Tony Simopoulos @ 2000-10-16 21:42 UTC (permalink / raw)
To: Clark, Joel <jclark@lendingtree.com>; +Cc: pgsql-interfaces
> 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
of failure
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.
tonys.
>
> -----Original Message-----
> From: Tony Simopoulos [mailto:karkalis@earthling.net]
> Sent: Monday, October 16, 2000 3:03 PM
> To: Oscar Serrano
> Cc: pgsql-interfaces@postgresql.org
> Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?
>
>
> a redundant, replicated, or parallel system (choose whichever adjective
> befits your desires) is being developed. check out
> http://www.erserver.com/.
>
> sharing a single disk is an O/S & hardware problem. what is your intended
> platform?
>
> good luck,
>
> tonys.
>
> ----- Original Message -----
> From: Oscar Serrano <oserra@fondos.net>
> To: Postgres interfaces <pgsql-interfaces@postgresql.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 postgres.
> > 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 them
> > 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
> from
> > the other server.
> > Esentially, what I want is, two postgres (one in each machine) with a
> shared
> > PGDATA directory, and that both postgres can access and do Inserts in the
> > tables, and when one postgres does an insert, the second sees what the
> first
> > has inserted.
> >
> > Thanks.
> >
> >
> >
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* RE: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 20:58 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
@ 2000-10-17 17:20 ` Oscar Serrano <oserra@fondos.net>
2000-10-17 19:00 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Tom Lane <tgl@sss.pgh.pa.us>
1 sibling, 1 reply; 15+ messages in thread
From: Oscar Serrano @ 2000-10-17 17:20 UTC (permalink / raw)
To: pgsql-interfaces
> -----Mensaje original-----
> De: pgsql-interfaces-owner@hub.org
> [mailto:pgsql-interfaces-owner@hub.org]En nombre de Clark, Joel
> Enviado el: lunes, 16 de octubre de 2000 22:58
> Para: 'Tony Simopoulos'; Oscar Serrano
> CC: pgsql-interfaces@postgresql.org
> Asunto: RE: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?
>
>
> Through an NFS mount maybe?
> a redundant, replicated, or parallel system (choose whichever adjective
> befits your desires) is being developed. check out
> http://www.erserver.com/.
I've been looking to this URL and seems great what they are doing. But they
give very few information. I don't know if they are going to do exactly what
I need.
> sharing a single disk is an O/S & hardware problem. what is your intended
> platform?
The platform is Linux. Both Linux access to the RAID by a NFS mount. I know
what I'm doing may be dangerous. There is a directory (/webpages) where I
put all web pages and scripts. And there is an Apache server on each linux
accessing this directory. It is not a problem because any script tries to
write to the same file at the same time.
But with postgres... ugh! here is a big problem. I've tried to start two
postgres, one in each Linux, and both having the PGDATA directory in the
RAID. Both postgres start correctly, but the changes one postgres does, are
not noticed by the second one.
It seems as if each change done in one postgres should be noticed to the
second one, so the second one should reread all system tables. Or something
like that :-?
Thank you all.
> good luck,
>
> tonys.
>
> ----- Original Message -----
> From: Oscar Serrano <oserra@fondos.net>
> To: Postgres interfaces <pgsql-interfaces@postgresql.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 postgres.
> > 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 them
> > 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
> from
> > the other server.
> > Esentially, what I want is, two postgres (one in each machine) with a
> shared
> > PGDATA directory, and that both postgres can access and do
> Inserts in the
> > tables, and when one postgres does an insert, the second sees what the
> first
> > has inserted.
> >
> > Thanks.
> >
> >
> >
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 20:58 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
2000-10-17 17:20 ` RE: 2 computers 1hd 2 postgres daemons. Is it possible? Oscar Serrano <oserra@fondos.net>
@ 2000-10-17 19:00 ` Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 15+ messages in thread
From: Tom Lane @ 2000-10-17 19:00 UTC (permalink / raw)
To: Oscar Serrano <oserra@fondos.net>; +Cc: pgsql-interfaces
"Oscar Serrano" <oserra@fondos.net> writes:
> But with postgres... ugh! here is a big problem. I've tried to start two
> postgres, one in each Linux, and both having the PGDATA directory in the
> RAID. Both postgres start correctly, but the changes one postgres does, are
> not noticed by the second one.
This will not work; don't even think of trying it, unless you want to
corrupt your database beyond repair.
Postgres depends on shared-memory communication among backends, not only
on disk files, so there is no chance of making this work.
regards, tom lane
^ permalink raw reply [nested|flat] 15+ messages in thread
* RE: 2 computers 1hd 2 postgres daemons. Is it possib le?
@ 2000-10-16 22:11 Clark, Joel <jclark@lendingtree.com>
2000-10-17 00:33 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Joseph Shraibman <jks@selectacast.net>
0 siblings, 1 reply; 15+ messages in thread
From: Clark, Joel @ 2000-10-16 22:11 UTC (permalink / raw)
To: 'Tony Simopoulos' <karkalis@earthling.net>; +Cc: pgsql-interfaces
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
requirements...
jc
-----Original Message-----
From: Tony Simopoulos [mailto:karkalis@earthling.net]
Sent: Monday, October 16, 2000 5:43 PM
To: Clark, Joel
Cc: pgsql-interfaces@postgresql.org
Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?
> 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
of failure
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.
tonys.
>
> -----Original Message-----
> From: Tony Simopoulos [mailto:karkalis@earthling.net]
> Sent: Monday, October 16, 2000 3:03 PM
> To: Oscar Serrano
> Cc: pgsql-interfaces@postgresql.org
> Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?
>
>
> a redundant, replicated, or parallel system (choose whichever adjective
> befits your desires) is being developed. check out
> http://www.erserver.com/.
>
> sharing a single disk is an O/S & hardware problem. what is your intended
> platform?
>
> good luck,
>
> tonys.
>
> ----- Original Message -----
> From: Oscar Serrano <oserra@fondos.net>
> To: Postgres interfaces <pgsql-interfaces@postgresql.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
postgres.
> > 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
them
> > 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
> from
> > the other server.
> > Esentially, what I want is, two postgres (one in each machine) with a
> shared
> > PGDATA directory, and that both postgres can access and do Inserts in
the
> > tables, and when one postgres does an insert, the second sees what the
> first
> > has inserted.
> >
> > Thanks.
> >
> >
> >
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 22:11 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
@ 2000-10-17 00:33 ` Joseph Shraibman <jks@selectacast.net>
2000-10-17 15:25 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Tony Simopoulos <karkalis@earthling.net>
0 siblings, 1 reply; 15+ messages in thread
From: Joseph Shraibman @ 2000-10-17 00:33 UTC (permalink / raw)
To: Clark, Joel <jclark@lendingtree.com>; +Cc: 'Tony Simopoulos' <karkalis@earthling.net>; pgsql-interfaces
"Clark, Joel" wrote:
>
> 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?
Yeah, they exist, though why they exist is beyond me. Maybe because
windows systems crash all the time. It doesn't make much sense to me,
after all it would seem that hard drive failure happens more often that
the system crashing for no reason.
--
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio. http://www.targabot.com
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?
2000-10-16 22:11 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
2000-10-17 00:33 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible? Joseph Shraibman <jks@selectacast.net>
@ 2000-10-17 15:25 ` Tony Simopoulos <karkalis@earthling.net>
0 siblings, 0 replies; 15+ messages in thread
From: Tony Simopoulos @ 2000-10-17 15:25 UTC (permalink / raw)
To: Joseph Shraibman <jks@selectacast.net>; +Cc: pgsql-interfaces
> "Clark, Joel" wrote:
> >
> > 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?
>
> Yeah, they exist, though why they exist is beyond me. Maybe because
> windows systems crash all the time. It doesn't make much sense to me,
> after all it would seem that hard drive failure happens more often that
> the system crashing for no reason.
>
they exist for a variety of reasons.
most importantly however, a hardware cluster was one of the first technologies on the scene (and still a very important one today)
that offered redundancy and load balancing. remember, a system often crashes, not because of hardware failure, or o/s failure
(excluding windows of course), but rather application software failure. the need for hardware redundancy solved that problem as
well as the remote problems of other non-disk related failures. just because a failure doesn't happen often doesn't mean it is
acceptable. how do you think the banks, or airline traffic controlers would feel about that?
Digital basically pioneered the entire front, as their hardware and o/s were most often used in critical systems demanding 100%
uptime. since then the technology has moved around a bit. (arguably, one of compaq's main interest's in digital was clustering
technology). most unix systems have some kind of clustering available. today, most outfits go the replication route. however, for
truly mission critical systems, replication is still not an acceptable option, for the simple reason of too much latency and lossy
performance. even with the giant leaps forward in network bandwidth, replication technology still has a long way to go before it
will be considered for the most critical of applications.
one of my major issues with postgresql is its contractidory stance on performance:
how can you be a frontier database with a (at best) sloppy high availability/load-balancing strategy?
tonys.
^ permalink raw reply [nested|flat] 15+ messages in thread
* RE: 2 computers 1hd 2 postgres daemons. Is it possib le?
@ 2000-10-17 08:33 Peter Mount <petermount@maidstone.gov.uk>
0 siblings, 0 replies; 15+ messages in thread
From: Peter Mount @ 2000-10-17 08:33 UTC (permalink / raw)
To: 'Clark, Joel' <jclark@lendingtree.com>; 'Tony Simopoulos' <karkalis@earthling.net>; Oscar Serrano <oserra@fondos.net>; +Cc: pgsql-interfaces
I think the problem is going to be how the two postgresql installations are
going to react to each other running on the same files at the same time.
I have a feeling there's going to be some horrible file locking but even
worse memory buffer problems lurking in there. If one backend writes to a
page, and the other also writes to the same page before the first has
flushed it's buffers, you'll end up with a corrupt table.
Peter
--
Peter Mount
Enterprise Support Officer, Maidstone Borough Council
Email: petermount@maidstone.gov.uk
WWW: http://www.maidstone.gov.uk
All views expressed within this email are not the views of Maidstone Borough
Council
-----Original Message-----
From: Clark, Joel [mailto:jclark@lendingtree.com]
Sent: Monday, October 16, 2000 9:58 PM
To: 'Tony Simopoulos'; Oscar Serrano
Cc: pgsql-interfaces@postgresql.org
Subject: RE: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possib le?
Through an NFS mount maybe?
-----Original Message-----
From: Tony Simopoulos [mailto:karkalis@earthling.net]
Sent: Monday, October 16, 2000 3:03 PM
To: Oscar Serrano
Cc: pgsql-interfaces@postgresql.org
Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?
a redundant, replicated, or parallel system (choose whichever adjective
befits your desires) is being developed. check out
http://www.erserver.com/.
sharing a single disk is an O/S & hardware problem. what is your intended
platform?
good luck,
tonys.
----- Original Message -----
From: Oscar Serrano <oserra@fondos.net>
To: Postgres interfaces <pgsql-interfaces@postgresql.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 postgres.
> 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 them
> 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
from
> the other server.
> Esentially, what I want is, two postgres (one in each machine) with a
shared
> PGDATA directory, and that both postgres can access and do Inserts in the
> tables, and when one postgres does an insert, the second sees what the
first
> has inserted.
>
> Thanks.
>
>
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?]
@ 2000-10-17 19:53 Adam Lang <aalang@rutgersinsurance.com>
2000-10-17 23:54 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Marc Rassbach <marc@milestonerdl.com>
0 siblings, 1 reply; 15+ messages in thread
From: Adam Lang @ 2000-10-17 19:53 UTC (permalink / raw)
To: pgsql-interfaces
Granted it probably not the most efficient solution, but if it is something
that is really a problem... what about having your dual server, one data
source setup, but the second server is idle and does nothing and only kicks
in if the primary drops? Might be more complicated to setup than it sounds
and there still would be a time delay for the second to pick up, but it
technically would eliminate the two servers butting heads. Again though,
not very efficient solution... unless it is very critical and money is no
object. :)
Adam Lang
Systems Engineer
Rutgers Casualty Insurance Company
----- Original Message -----
From: "Joseph Shraibman" <jks@selectacast.net>
To: <pgsql-interfaces@postgreSQL.org>
Sent: Tuesday, October 17, 2000 2:53 PM
Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?]
>
> --
> Joseph Shraibman
> jks@selectacast.net
> Increase signal to noise ratio. http://www.targabot.com
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?]
2000-10-17 19:53 Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Adam Lang <aalang@rutgersinsurance.com>
@ 2000-10-17 23:54 ` Marc Rassbach <marc@milestonerdl.com>
2000-10-18 01:14 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Joseph Shraibman <jks@selectacast.net>
0 siblings, 1 reply; 15+ messages in thread
From: Marc Rassbach @ 2000-10-17 23:54 UTC (permalink / raw)
To: Adam Lang <aalang@rutgersinsurance.com>; +Cc: pgsql-interfaces
And there DOES come a time where PostgreSQL is not the correct solution.
At this time you can not mirror a postgreSQL server like you can mirror a,
say Oracle server. It sounds like they want mirroring servers the way
some commerical servers can do.
Nothing stopping your employer/patron/slave driver from paying someone to
develop this kind of feature in postgreSQL.
And nothing stopping you from re-writting the app such that the app
worries about mirroring the data. (IE, it makes sure it has its own
transaction set in case it can't talk to the other server, and all queries
are duplicated on the other box.)
On Tue, 17 Oct 2000, Adam Lang wrote:
> Granted it probably not the most efficient solution, but if it is something
> that is really a problem... what about having your dual server, one data
> source setup, but the second server is idle and does nothing and only kicks
> in if the primary drops? Might be more complicated to setup than it sounds
> and there still would be a time delay for the second to pick up, but it
> technically would eliminate the two servers butting heads. Again though,
> not very efficient solution... unless it is very critical and money is no
> object. :)
>
> Adam Lang
> Systems Engineer
> Rutgers Casualty Insurance Company
> ----- Original Message -----
> From: "Joseph Shraibman" <jks@selectacast.net>
> To: <pgsql-interfaces@postgreSQL.org>
> Sent: Tuesday, October 17, 2000 2:53 PM
> Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?]
>
>
> >
> > --
> > Joseph Shraibman
> > jks@selectacast.net
> > Increase signal to noise ratio. http://www.targabot.com
>
>
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: 2 computers 1hd 2 postgres daemons. Is it possible?]
2000-10-17 19:53 Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Adam Lang <aalang@rutgersinsurance.com>
2000-10-17 23:54 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Marc Rassbach <marc@milestonerdl.com>
@ 2000-10-18 01:14 ` Joseph Shraibman <jks@selectacast.net>
0 siblings, 0 replies; 15+ messages in thread
From: Joseph Shraibman @ 2000-10-18 01:14 UTC (permalink / raw)
To: Marc Rassbach <marc@milestonerdl.com>; +Cc: Adam Lang <aalang@rutgersinsurance.com>; pgsql-interfaces
I guess you missed the announcement. This *is* coming to postgres, but
I'm unclear if it is going to be included or it will be a seperate
package.
Marc Rassbach wrote:
>
> And there DOES come a time where PostgreSQL is not the correct solution.
>
> At this time you can not mirror a postgreSQL server like you can mirror a,
> say Oracle server. It sounds like they want mirroring servers the way
> some commerical servers can do.
>
> Nothing stopping your employer/patron/slave driver from paying someone to
> develop this kind of feature in postgreSQL.
>
> And nothing stopping you from re-writting the app such that the app
> worries about mirroring the data. (IE, it makes sure it has its own
> transaction set in case it can't talk to the other server, and all queries
> are duplicated on the other box.)
>
>
> On Tue, 17 Oct 2000, Adam Lang wrote:
>
> > Granted it probably not the most efficient solution, but if it is something
> > that is really a problem... what about having your dual server, one data
> > source setup, but the second server is idle and does nothing and only kicks
> > in if the primary drops? Might be more complicated to setup than it sounds
> > and there still would be a time delay for the second to pick up, but it
> > technically would eliminate the two servers butting heads. Again though,
> > not very efficient solution... unless it is very critical and money is no
> > object. :)
> >
> > Adam Lang
> > Systems Engineer
> > Rutgers Casualty Insurance Company
> > ----- Original Message -----
> > From: "Joseph Shraibman" <jks@selectacast.net>
> > To: <pgsql-interfaces@postgreSQL.org>
> > Sent: Tuesday, October 17, 2000 2:53 PM
> > Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> > possible?]
> >
> >
> > >
> > > --
> > > Joseph Shraibman
> > > jks@selectacast.net
> > > Increase signal to noise ratio. http://www.targabot.com
> >
> >
--
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio. http://www.targabot.com
^ permalink raw reply [nested|flat] 15+ messages in thread
* RE: 2 computers 1hd 2 postgres daemons. Is it possib le?]
@ 2000-10-17 20:51 Clark, Joel <jclark@lendingtree.com>
0 siblings, 0 replies; 15+ messages in thread
From: Clark, Joel @ 2000-10-17 20:51 UTC (permalink / raw)
To: 'Adam Lang' <aalang@rutgersinsurance.com>; pgsql-interfaces
As long as the requirement is only fail-over and not load-balancing, it
*might* be doable...but running against tables mounted across NFS will still
be slow, relatively speaking...
jc
-----Original Message-----
From: Adam Lang [mailto:aalang@rutgersinsurance.com]
Sent: Tuesday, October 17, 2000 3:54 PM
To: pgsql-interfaces@postgreSQL.org
Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?]
Granted it probably not the most efficient solution, but if it is something
that is really a problem... what about having your dual server, one data
source setup, but the second server is idle and does nothing and only kicks
in if the primary drops? Might be more complicated to setup than it sounds
and there still would be a time delay for the second to pick up, but it
technically would eliminate the two servers butting heads. Again though,
not very efficient solution... unless it is very critical and money is no
object. :)
Adam Lang
Systems Engineer
Rutgers Casualty Insurance Company
----- Original Message -----
From: "Joseph Shraibman" <jks@selectacast.net>
To: <pgsql-interfaces@postgreSQL.org>
Sent: Tuesday, October 17, 2000 2:53 PM
Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
possible?]
>
> --
> Joseph Shraibman
> jks@selectacast.net
> Increase signal to noise ratio. http://www.targabot.com
^ permalink raw reply [nested|flat] 15+ messages in thread
* Re: RE: 2 computers 1hd 2 postgres daemons. Is it possib
@ 2000-10-17 21:35 Luc Bouchard <luc@luker.on.ca>
0 siblings, 0 replies; 15+ messages in thread
From: Luc Bouchard @ 2000-10-17 21:35 UTC (permalink / raw)
To: pgsql-interfaces
In any of these situations your external RAID array must have two channels.
1) in a fail-over situation your postgresql daemon must be started after the
other box fails. When it starts it will read the current state of the
filesystem
and may be able to read the tables as they were when the last write occurred
on
the first box.
2) in an High Availability (HA) situation you need some sort of database
broker
that keeps both database daemons happy. Something like Oracle's Parallel
server
option. This also involves row-level locking of records.
HA or Fail-over are very expensive solutions (hardware and software required)
and therefore you need to question whether you really want to do this.
On Tue, 17 Oct 2000 16:51:35 -0400, "Clark, Joel" <jclark@lendingtree.com>
wrote:
> As long as the requirement is only fail-over and not load-balancing, it
> *might* be doable...but running against tables mounted across NFS will still
> be slow, relatively speaking...
>
> jc
>
> -----Original Message-----
> From: Adam Lang [mailto:aalang@rutgersinsurance.com]
> Sent: Tuesday, October 17, 2000 3:54 PM
> To: pgsql-interfaces@postgreSQL.org
> Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?]
>
>
> Granted it probably not the most efficient solution, but if it is something
> that is really a problem... what about having your dual server, one data
> source setup, but the second server is idle and does nothing and only kicks
> in if the primary drops? Might be more complicated to setup than it sounds
> and there still would be a time delay for the second to pick up, but it
> technically would eliminate the two servers butting heads. Again though,
> not very efficient solution... unless it is very critical and money is no
> object. :)
>
> Adam Lang
> Systems Engineer
> Rutgers Casualty Insurance Company
> ----- Original Message -----
> From: "Joseph Shraibman" <jks@selectacast.net>
> To: <pgsql-interfaces@postgreSQL.org>
> Sent: Tuesday, October 17, 2000 2:53 PM
> Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?]
>
>
> >
> > --
> > Joseph Shraibman
> > jks@selectacast.net
> > Increase signal to noise ratio. http://www.targabot.com
>
^ permalink raw reply [nested|flat] 15+ messages in thread
end of thread, other threads:[~2000-10-18 01:14 UTC | newest]
Thread overview: 15+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2000-10-16 18:15 2 computers 1hd 2 postgres daemons. Is it possible? Oscar Serrano <oserra@fondos.net>
2000-10-16 19:03 ` Tony Simopoulos <karkalis@earthling.net>
2000-10-16 20:58 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
2000-10-16 21:42 ` Tony Simopoulos <karkalis@earthling.net>
2000-10-17 17:20 ` Oscar Serrano <oserra@fondos.net>
2000-10-17 19:00 ` Tom Lane <tgl@sss.pgh.pa.us>
2000-10-16 22:11 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Clark, Joel <jclark@lendingtree.com>
2000-10-17 00:33 ` Joseph Shraibman <jks@selectacast.net>
2000-10-17 15:25 ` Tony Simopoulos <karkalis@earthling.net>
2000-10-17 08:33 RE: 2 computers 1hd 2 postgres daemons. Is it possib le? Peter Mount <petermount@maidstone.gov.uk>
2000-10-17 19:53 Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Adam Lang <aalang@rutgersinsurance.com>
2000-10-17 23:54 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Marc Rassbach <marc@milestonerdl.com>
2000-10-18 01:14 ` Re: 2 computers 1hd 2 postgres daemons. Is it possible?] Joseph Shraibman <jks@selectacast.net>
2000-10-17 20:51 RE: 2 computers 1hd 2 postgres daemons. Is it possib le?] Clark, Joel <jclark@lendingtree.com>
2000-10-17 21:35 Re: RE: 2 computers 1hd 2 postgres daemons. Is it possib Luc Bouchard <luc@luker.on.ca>
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