Re: PostgreSQL and a clustered file system

On 11/12/2012 1:52 PM, Gunnar "Nick" Bluth wrote:
> Am 12.11.2012 11:03, schrieb Ivan Voras:
>>
>>
>> Is anyone running PostgreSQL on a clustered file system on Linux? By
>> "clustered" I actually mean "shared", such that the same storage is
>> mounted by different servers at the same time (of course, only one
>> instance of PostgreSQL on only one server can be running on such a
>> setup, and there are a lot of other precautions that need to be
>> satisfied).
>>
>>
> TBTH, I don't see the potential benefit. Clustered filesystems have
> benefits for special use cases (e.g. redundant fileservers or
> applications that actually can work in parallel, relying on file
> locking, DB clusters that coordinate writes themselves, ...), but PG
> certainly is not one of these...

Although I'm also a non-fan of database over clustered filesystems, I
wanted to speak up here since I have a hunch the OP wasn't looking for
the solution you're thinking of. I think he's asking if folk have run an
"HA" setup with PG where the database files are stored in a
dual-ported/clustered filesystem, the idea being that you can have a
failure in the hardware for one DB server, and make the other one take
over using the same underlying files. I've seen this done. You need some
plumbing to ensure that only one PG instance can run at the same time.
From memory, there are HA monitor tools available that do this in a
generic way. As far as PG is concerned it has no idea there is a shared
access filesystem, and so it has no need to perform file-level locking.