Andrew Sullivan <ajs at crankycanuck.ca> writes:
> On Mon, Oct 25, 2010 at 11:44:35AM -0400, Mark Steben wrote:
>> We’re running postgres 8.3.11.  Do you have any recommendations
>> Using a physical server for the master and a vm server for the only slave?
>> Are there any restrictions / potential gotchas I should be ware of?
>
> Test -- really, really test -- the I/O capacity of your vmware target.
> My previous (now aged) tests in this area suggested to me that there
> was a very serious penalty.  Slony systems are almost always I/O bound
> when they get into trouble.
>
> Other than that, it's just another box, AFAICT.

And for the most part, none of this has anything to do with Slony, per
se - the issues are surrounding running a database on virtualized
hardware.

The *really* notable issues people have found have involved running
databases "in the cloud," as with products like Amazon EC2.

And I suppose that this fits in somewhat with the Oracle "thing" of
liking to run atop raw disk.  Oracle particularly likes that.  

In contrast, Postgres has always remained agnostic of specific hardware
knowledge, preferring to take advantage of the filesystems improvements
taking place in OS platforms.  Nobody wants to have to take over
implementing filesystems, and such.

But the issues relating to virtualization demonstrate that we're not all
that distant from Oracle; if you put *too* many layers of emulation
between your database and the hardware it's actually using, there's
trouble to be found...
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Christopher Browne
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