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* question about HA in PG 9.0
@ 2010-09-17 23:30 Kasia Tuszynska <ktuszynska@esri.com>
2010-09-18 03:15 ` Re: question about HA in PG 9.0 Greg Smith <greg@2ndquadrant.com>
2010-09-18 06:38 ` Re: question about HA in PG 9.0 Thomas Kellerer <spam_eater@gmx.net>
2010-09-20 14:55 ` Re: question about HA in PG 9.0 Anibal David Acosta <anibal.acosta@edge.com.py>
0 siblings, 3 replies; 5+ messages in thread
From: Kasia Tuszynska @ 2010-09-17 23:30 UTC (permalink / raw)
To: pgsql-admin
Hi Everybody,
I am doing a bit of research about High Availability solutions offered as part of core in Postges 9.0, I have couple of questions, sorry if they expose my novice status where it comes to HA on Postgres:
1. The doc is lovely but all of the examples are for linux, has anyone tired a Hot Standby streaming scenario on windows? Any issues specific to windows? I know that linux and windows environments "should" behave the same but actually running in both of those environments exposes many differences.
2. I am reading the Beta4 doc where under section 25.3 Failover it says:
"PostgreSQL does not provide the system software required to identify a failure on the primary and notify the standby database server. Many such tools exist and are well integrated with the operating system facilities required for successful failover, such as IP address migration."
I have been reading up on this issue most notably on http://wiki.postgresql.org/wiki/Shared_Storage, where the suggestions have been gravitating to solutions on the physical level.
Are there any software level solutions? ( I have a feeling that this may be a stupid question, but I want to implement this in the cloud, and not potentially kill an ami instance)
I found a presentation by Heikki Linnakangas where he mentions: Heartbeat and Shoot the other Node in the head as types of 3rd party high availability tools, does anyone have any recommendations of specific software packages?
Thank you,
Sincerely,
Kasia
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: question about HA in PG 9.0
2010-09-17 23:30 question about HA in PG 9.0 Kasia Tuszynska <ktuszynska@esri.com>
@ 2010-09-18 03:15 ` Greg Smith <greg@2ndquadrant.com>
2 siblings, 0 replies; 5+ messages in thread
From: Greg Smith @ 2010-09-18 03:15 UTC (permalink / raw)
To: Kasia Tuszynska <ktuszynska@esri.com>; +Cc: pgsql-admin
Kasia Tuszynska wrote:
>
> The doc is lovely but all of the examples are for linux, has anyone
> tired a Hot Standby streaming scenario on windows? Any issues
> specific to windows? I know that linux and windows environments
> "should" behave the same but actually running in both of those
> environments exposes many differences.
>
As there is a certain amount of helper scripting required to get
Streaming Replication setup, and the usual scripting languages people
tend to write them in (bash, Python, Perl) don't ship with Windows, you
will have a bit of extra work to do here. I'm not aware of any
production-quality setups that have tested the 9.0 implementation under
Windows yet, but the similar hard parts have certainly been done before
with earlier versions.
> I have been reading up on this issue most notably on
> http://wiki.postgresql.org/wiki/Shared_Storage, where the suggestions
> have been gravitating to solutions on the physical level.
>
> Are there any software level solutions? ( I have a feeling that this
> may be a stupid question, but I want to implement this in the cloud,
> and not potentially kill an ami instance)
>
The only way you will implement "Shoot the other node in the head" on
EC2 approaching the same level of reliability a hardware solution
provides is to do just that: don't begin failover to a new node until
you've made sure the unreponsive master has been killed, and its AMI
instance disabled from powering back up again. Automating that is
exactly where I plan to go with redundant EC2 deployments of this type.
But you could do it as part of a manual failover if you had to. You
cannot let the original master touch the shared data store ever again
once it's been taken out of the loop. If your storage is on EBS, I'm
not sure how that handles two attempts to attach a writer to the store,
but you'd want to test that out too.
--
Greg Smith, 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services and Support www.2ndQuadrant.us
Author, "PostgreSQL 9.0 High Performance" Pre-ordering at:
https://www.packtpub.com/postgresql-9-0-high-performance/book
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: question about HA in PG 9.0
2010-09-17 23:30 question about HA in PG 9.0 Kasia Tuszynska <ktuszynska@esri.com>
@ 2010-09-18 06:38 ` Thomas Kellerer <spam_eater@gmx.net>
2 siblings, 0 replies; 5+ messages in thread
From: Thomas Kellerer @ 2010-09-18 06:38 UTC (permalink / raw)
To: pgsql-admin
Kasia Tuszynska wrote on 18.09.2010 01:30:
> 1. The doc is lovely but all of the examples are for linux, has
> anyone tired a Hot Standby streaming scenario on windows? Any issues
> specific to windows? I know that linux and windows environments
> “should” behave the same but actually running in both of those
> environments exposes many differences.
I had no problem setting up a proof-of-concept on my Windows laptop with streaming replication and both instances running on my computer. The batch files needed were quite simple.
Regards
Thomas
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: question about HA in PG 9.0
2010-09-17 23:30 question about HA in PG 9.0 Kasia Tuszynska <ktuszynska@esri.com>
@ 2010-09-20 14:55 ` Anibal David Acosta <anibal.acosta@edge.com.py>
2010-09-25 03:29 ` Re: question about HA in PG 9.0 Greg Smith <greg@2ndquadrant.com>
2 siblings, 1 reply; 5+ messages in thread
From: Anibal David Acosta @ 2010-09-20 14:55 UTC (permalink / raw)
To: 'Kasia Tuszynska' <ktuszynska@esri.com>; pgsql-admin
Windows server enterprise has the Microsoft Cluster Services.
This enable fail-over scenario between two computers.
So, when one of them go offline, the other is activated, this involve many
steps, including IP changing, the slave become the master IP address .
But you can choose between has a replication between both postgres or maybe
you can put your postgresql DATA directory to an external storage shared
between those two servers.
If this case, when the second server become available the Cluster service
map map the DATA unit and starts the postgres service.
So, you have everything running and working in aprox. 10 seconds.
De: pgsql-admin-owner@postgresql.org
[mailto:pgsql-admin-owner@postgresql.org] En nombre de Kasia Tuszynska
Enviado el: viernes, 17 de septiembre de 2010 07:30 p.m.
Para: pgsql-admin@postgresql.org
Asunto: [ADMIN] question about HA in PG 9.0
Hi Everybody,
I am doing a bit of research about High Availability solutions offered as
part of core in Postges 9.0, I have couple of questions, sorry if they
expose my novice status where it comes to HA on Postgres:
1. The doc is lovely but all of the examples are for linux, has anyone
tired a Hot Standby streaming scenario on windows? Any issues specific to
windows? I know that linux and windows environments "should" behave the
same but actually running in both of those environments exposes many
differences.
2. I am reading the Beta4 doc where under section 25.3 Failover it
says:
"PostgreSQL does not provide the system software required to identify a
failure on the primary and notify the standby database server. Many such
tools exist and are well integrated with the operating system facilities
required for successful failover, such as IP address migration."
I have been reading up on this issue most notably on
http://wiki.postgresql.org/wiki/Shared_Storage, where the suggestions have
been gravitating to solutions on the physical level.
Are there any software level solutions? ( I have a feeling that this may be
a stupid question, but I want to implement this in the cloud, and not
potentially kill an ami instance)
I found a presentation by Heikki Linnakangas where he mentions: Heartbeat
and Shoot the other Node in the head as types of 3rd party high availability
tools, does anyone have any recommendations of specific software packages?
Thank you,
Sincerely,
Kasia
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: question about HA in PG 9.0
2010-09-17 23:30 question about HA in PG 9.0 Kasia Tuszynska <ktuszynska@esri.com>
2010-09-20 14:55 ` Re: question about HA in PG 9.0 Anibal David Acosta <anibal.acosta@edge.com.py>
@ 2010-09-25 03:29 ` Greg Smith <greg@2ndquadrant.com>
0 siblings, 0 replies; 5+ messages in thread
From: Greg Smith @ 2010-09-25 03:29 UTC (permalink / raw)
To: Anibal David Acosta <anibal.acosta@edge.com.py>; +Cc: Kasia Tuszynska <ktuszynska@esri.com>; pgsql-admin
Anibal David Acosta wrote:
>
> Windows server enterprise has the Microsoft Cluster Services.
>
> This enable fail-over scenario between two computers.
>
> So, when one of them go offline, the other is activated, this involve
> many steps, including IP changing, the slave become the master IP
> address .
>
> But you can choose between has a replication between both postgres or
> maybe you can put your postgresql DATA directory to an external
> storage shared between those two servers.
>
> If this case, when the second server become available the Cluster
> service map map the DATA unit and starts the postgres service.
>
> So, you have everything running and working in aprox. 10 seconds.
>
All of the Windows Server stuff via Microsoft Cluster Services I'm aware
of does its shared storage node fencing via sending specific SCSI calls
(PERSISTENT RESERVE) to the storage. That probably works fine if you
have a Fiber Channel array that supports that. But I don't think
there's any flexibility for alternative types of deployments. As for
the complexity of the setup time, while they have put a bunch of GUIs on
it I've never see anything that tries to do complicated storage array
arrangements work in any time that isn't measure in large multiples of
hours, so "10 seconds" I'm skeptical of.
--
Greg Smith, 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services and Support www.2ndQuadrant.us
Author, "PostgreSQL 9.0 High Performance" Pre-ordering at:
https://www.packtpub.com/postgresql-9-0-high-performance/book
^ permalink raw reply [nested|flat] 5+ messages in thread
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2010-09-17 23:30 question about HA in PG 9.0 Kasia Tuszynska <ktuszynska@esri.com>
2010-09-18 03:15 ` Greg Smith <greg@2ndquadrant.com>
2010-09-18 06:38 ` Thomas Kellerer <spam_eater@gmx.net>
2010-09-20 14:55 ` Anibal David Acosta <anibal.acosta@edge.com.py>
2010-09-25 03:29 ` Greg Smith <greg@2ndquadrant.com>
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