PostgreSQL Administration - Re: 100% failover + replication solution

Author

Re: 100% failover + replication solution

Bruce Momjian

2006-11-14, 7:19 pm

I wrote this for the 8.2 documentation. Let me know if it helps or you
have other suggestions:

http://developer.postgresql.org/pgd...s/failover.html

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Moiz Kothari wrote:
> Guys,
>
> I have been thinking about this and wanted to see if it can be achived. I
> wanted to make a 100% failover solution for my postgres databases. The first
> thing that comes to my mind is doing it using WAL logs. Am attaching the
> diagram for which i will write more here.
>
> I was thinking if i can have Hotsync the databases using the WAL logs. If
> you see the architecture, the select goes to the SLAVE nodes and the INSERTS
> goes to the MASTER database, that means there should be no transactions
> happening on SLAVES (pure select). not even using "plpgsql". In this
> archecture i wont even mind restarting the SLAVE nodes if i need to.
>
> I was reading on PIT recovery on postgres, the only current problem i am
> facing with that is, i need to backup the database and move the slaves and
> the apply WAL logs to it. That could be huge amount of transfer and hence a
> longer downtime then moving 16mb WAL log files.
>
> Can someone help me out here, what i want is a continuous applying of WAL
> logs once i have brought the database up. I want to elimiate the backup of
> master to be restored to the slaves everytime i want to apply WAL to slaves.
> It would be real help if someone can tell me if it is possible to apply WAL
> logs to the slaves continously as soon as they are created on MASTER. I
> checked other tools available and thougth this would be best approach if it
> works.
>
> Awaiting reply soon.
>
> Regards,
> Moiz Kothari

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Bruce Momjian bruce@momjian.us
EnterpriseDB http://www.enterprisedb.com

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Brad Nicholson

2006-11-15, 7:34 pm

Excellent addition. I suggest in 24.1 - Shared Disk Failover something
about the risk of having two postmasters come up on the same data
directory, which is entirely possible if the old master doesn't release
the disk in time.

On Tue, 2006-11-14 at 15:11 -0500, Bruce Momjian wrote:
> I wrote this for the 8.2 documentation. Let me know if it helps or you
> have other suggestions:
>
> http://developer.postgresql.org/pgd...s/failover.html
>
> ---------------------------------------------------------------------------
>
> Moiz Kothari wrote:
>
> [ Attachment, skipping... ]
>
>
--
Brad Nicholson 416-673-4106
Database Administrator, Afilias Canada Corp.

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Bruce Momjian

2006-11-18, 12:13 am

Brad Nicholson wrote:
> Excellent addition. I suggest in 24.1 - Shared Disk Failover something
> about the risk of having two postmasters come up on the same data
> directory, which is entirely possible if the old master doesn't release
> the disk in time.

I have added a mention of this.

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>
>
>
> On Tue, 2006-11-14 at 15:11 -0500, Bruce Momjian wrote:
> --
> Brad Nicholson 416-673-4106
> Database Administrator, Afilias Canada Corp.
>
>
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--
Bruce Momjian bruce@momjian.us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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