Hi Merlin. Thanks very much for your reply. We are not using the "High-CPU" instance type, so these kernel
recommendationsto not apply to us. Here is what we're running:
$ uname -a
Linux domU-12-31-39-09-E8-21 2.6.21.7-2.fc8xen #1 SMP Fri Feb 15 12:34:28 EST 2008 x86_64 x86_64 x86_64 GNU/Linux
Regarding Xen, I'll look around a bit, but one of my first Google hits was the following thread:
http://archives.postgresql.org/pgsql-general/2006-09/msg00503.php
Some quotes:
"PostgreSQL performs very, very well on Xen even in DomU. It is one of the things that lends to the Xen credibility
becausethey use us in their benchmarks."
"... I've had zero issues running postgres inside a domU."
Granted, this was in 2006.
-- Matt
On Nov 20, 2009, at 9:54 AM, Merlin Moncure wrote:
> On Fri, Nov 20, 2009 at 12:15 PM, Matt Solnit <msolnit@soasta.com> wrote:
>>
>> We are running PostgreSQL 8.3.8 (64-bit) on a dedicated Fedora Core 8 machine, in Amazon EC2. This was using an
"extra-large"instance, which means 4 Xeon cores (2.66 GHz) and 15.5 GB of memory.
>
> considering that ec2 is a virtualized environment, the first
> conclusion that everyone is going to jump to is that this is some type
> of issue with ec2. IIRC ec2 runs xen, did you search for any related
> issues with xen and postgresql?
>
> are you running the correct kernel?
> http://developer.amazonwebservices.com/connect/entry.jspa?externalID=1535
>
> "We strongly recommend using the 2.6.18 Xen stock kernel with the
> c1.medium and c1.xlarge instances. Although the default Amazon EC2
> kernels will work, the new kernels provide greater stability and
> performance for these instance types. For more information about
> kernels, refer to the Amazon Elastic Compute Cloud Developer Guide."
>
> merlin