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

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.'

-- 
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin