Thread: PG server clustering
We are assisting in the system administration of a partner that uses PostGres in a mission critical position in their system. They have mail servers and other things that rely on 24/7 availability for the postgres server. They are running postgres 9.04 on redhat linux (2.6.32-131.0.15.el6.x86_64). This is running on one old machine, and thus does not really provide the liability they looking for.
I had the thought that I could set up another server as a slave, then promote the slave in the event it’s necessary. I was trying I made a system that watches for a change in the IP number number of the server in dns, then downs the primary, swaps primary-secondary configs in the primary, restarts the primary, then does the same in the secondary. This actually worked on the first test from failing the primary to the secondary. The problem came when I stried to switch it back. When I tried to restart the original primary as secondary, it failed saying the database was corrupted.
There are a couple of possible solutions to this, but I’m starting to think that what they probably really want anyway is a Postgres server cluster of two servers that stay in synch with each other, and can simultaneously accept read and write requests. Are there any opinions here about the best way to set this up?
On 10/17/2013 12:32 PM, Joseph Mays wrote: > We are assisting in the system administration of a partner that uses > PostGres in a mission critical position in their system. They have mail > servers and other things that rely on 24/7 availability for the postgres > server. They are running postgres 9.04 on redhat linux > (2.6.32-131.0.15.el6.x86_64). This is running on one old machine, and > thus does not really provide the liability they looking for. > I had the thought that I could set up another server as a slave, then > promote the slave in the event it’s necessary. I was trying I made a > system that watches for a change in the IP number number of the server > in dns, then downs the primary, swaps primary-secondary configs in the > primary, restarts the primary, then does the same in the secondary. This > actually worked on the first test from failing the primary to the > secondary. The problem came when I stried to switch it back. When I > tried to restart the original primary as secondary, it failed saying the > database was corrupted. This is completely possible if configured correctly, we do this all the time for customers. > There are a couple of possible solutions to this, but I’m starting to > think that what they probably really want anyway is a Postgres server > cluster of two servers that stay in synch with each other, and can > simultaneously accept read and write requests. Are there any opinions > here about the best way to set this up? There is no "good" way to do this. There are some application specific ways but it depends on their needs. Joshua D. Drake -- Command Prompt, Inc. - http://www.commandprompt.com/ 509-416-6579 PostgreSQL Support, Training, Professional Services and Development High Availability, Oracle Conversion, Postgres-XC, @cmdpromptinc For my dreams of your image that blossoms a rose in the deeps of my heart. - W.B. Yeats
Hey,
You can have a look at Mimeo (https://github.com/omniti-labs/mimeo) which is a specialized replication tool, through which you can have two servers that are constantly in sync with each other and both can accept read and write requests.
Mimeo does its replication on a per-table basis, and so you will have to set up replication for each table, wherein you have various types of replication mechanisms you can choose from. All this is pretty well explained in the docs.
On Thu, Oct 17, 2013 at 4:23 PM, Joshua D. Drake <jd@commandprompt.com> wrote:
This is completely possible if configured correctly, we do this all the time for customers.
On 10/17/2013 12:32 PM, Joseph Mays wrote:We are assisting in the system administration of a partner that uses
PostGres in a mission critical position in their system. They have mail
servers and other things that rely on 24/7 availability for the postgres
server. They are running postgres 9.04 on redhat linux
(2.6.32-131.0.15.el6.x86_64). This is running on one old machine, and
thus does not really provide the liability they looking for.
I had the thought that I could set up another server as a slave, then
promote the slave in the event it’s necessary. I was trying I made a
system that watches for a change in the IP number number of the server
in dns, then downs the primary, swaps primary-secondary configs in the
primary, restarts the primary, then does the same in the secondary. This
actually worked on the first test from failing the primary to the
secondary. The problem came when I stried to switch it back. When I
tried to restart the original primary as secondary, it failed saying the
database was corrupted.There is no "good" way to do this. There are some application specific ways but it depends on their needs.There are a couple of possible solutions to this, but I’m starting to
think that what they probably really want anyway is a Postgres server
cluster of two servers that stay in synch with each other, and can
simultaneously accept read and write requests. Are there any opinions
here about the best way to set this up?
Joshua D. Drake
--
Command Prompt, Inc. - http://www.commandprompt.com/ 509-416-6579
PostgreSQL Support, Training, Professional Services and Development
High Availability, Oracle Conversion, Postgres-XC, @cmdpromptinc
For my dreams of your image that blossoms
a rose in the deeps of my heart. - W.B. Yeats
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Looks like you should check out the following instead, which are better suited to your needs of a multi-master replication system :
On Thu, Oct 17, 2013 at 4:49 PM, Joseph Mays <mays@win.net> wrote:
Thanks! I’ll check it out.From: Payal SinghSent: Thursday, October 17, 2013 4:30 PMTo: Joshua D. DrakeSubject: Re: [ADMIN] PG server clusteringHey,You can have a look at Mimeo (https://github.com/omniti-labs/mimeo) which is a specialized replication tool, through which you can have two servers that are constantly in sync with each other and both can accept read and write requests.Mimeo does its replication on a per-table basis, and so you will have to set up replication for each table, wherein you have various types of replication mechanisms you can choose from. All this is pretty well explained in the docs.On Thu, Oct 17, 2013 at 4:23 PM, Joshua D. Drake <jd@commandprompt.com> wrote:This is completely possible if configured correctly, we do this all the time for customers.
On 10/17/2013 12:32 PM, Joseph Mays wrote:We are assisting in the system administration of a partner that uses
PostGres in a mission critical position in their system. They have mail
servers and other things that rely on 24/7 availability for the postgres
server. They are running postgres 9.04 on redhat linux
(2.6.32-131.0.15.el6.x86_64). This is running on one old machine, and
thus does not really provide the liability they looking for.
I had the thought that I could set up another server as a slave, then
promote the slave in the event it’s necessary. I was trying I made a
system that watches for a change in the IP number number of the server
in dns, then downs the primary, swaps primary-secondary configs in the
primary, restarts the primary, then does the same in the secondary. This
actually worked on the first test from failing the primary to the
secondary. The problem came when I stried to switch it back. When I
tried to restart the original primary as secondary, it failed saying the
database was corrupted.There is no "good" way to do this. There are some application specific ways but it depends on their needs.There are a couple of possible solutions to this, but I’m starting to
think that what they probably really want anyway is a Postgres server
cluster of two servers that stay in synch with each other, and can
simultaneously accept read and write requests. Are there any opinions
here about the best way to set this up?
Joshua D. Drake
--
Command Prompt, Inc. - http://www.commandprompt.com/ 509-416-6579
PostgreSQL Support, Training, Professional Services and Development
High Availability, Oracle Conversion, Postgres-XC, @cmdpromptinc
For my dreams of your image that blossoms
a rose in the deeps of my heart. - W.B. Yeats
--
Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
To make changes to your subscription:
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On Thu, Oct 17, 2013 at 04:51:21PM -0400, Payal Singh wrote: > Looks like you should check out the following instead, which are better > suited to your needs of a multi-master replication system : > http://postgres-r.org/ > http://bucardo.org/ > Also http://postgres-xc.sourceforge.net could be an option. Cheers, Ken