Re: question about HA in PG 9.0

[Greg Smith <greg@xxxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxxx Baltimore, MD
PostgreSQL Training, Services and Support  www.2ndQuadrant.us
Author, "PostgreSQL 9.0 High Performance"    Pre-ordering at:
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