Re: Fault Tolerant Postgresql (two machines, two postmasters, one disk array)

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On 05/11/07 08:31, Geoffrey wrote:
> Ron Johnson wrote:
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>> On 05/11/07 07:32, Geoffrey wrote:
>>> John Gateley wrote:
>>>> Sorry if this is a FAQ, I did search and couldn't find much.
>>>>
>>>> I need to make my Postgresql installation fault tolerant.
>>>> I was imagining a RAIDed disk array that is accessible from two
>>>> (or multiple) computers, with a postmaster running on each computer.
>>>> (Hardware upgrades could then be done to each computer at different
>>>> times without losing access to the database).
>>> We are doing this, more or less. We use the RH cluster suite on two
>>> machines that share a common data silo. Basically, if one machine
>>> fails, the other fires up a postmaster and picks up where the other left
>>> off.
>>>
>>> That's real simple description because we actually have an active/active
>>> configuration with multiple postmasters running on each machine. Machine
>>> A is the active machine for databases 1-3 and machine B is the active
>>> machine for databases 4-6. If machine A fails, postmasters are fired
>>> up on machine B to attend to databases 1-3.
>>
>> That's still not a cluster in the traditional sense.
>>
>> On a cluster-aware OS and RDBMS (like Rdb/VMS and Oracle RAC, which
>> imperfectly got it's technology from VMS), all the databases would
>> be open on both nodes and they would share locking over a (usually
>> dedicated, and used-to-be-proprietary) network link.
>
> Regardless of what you want to call it, it certainly seems to reflect a
> solution the user might consider. I don't believe I called it a
> cluster. I stated we were using software called the 'cluster suite.'

Call me elitist, but I've used OpenVMS for so long that if it's not
a VMS-style shared-disk cluster, it's a false usage of the word.

Compute-clusters excluded, of course.

- --
Ron Johnson, Jr.
Jefferson LA USA

Give a man a fish, and he eats for a day.
Hit him with a fish, and he goes away for good!

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