Xen and the art of Database performance

J. Refugio Rodriguez jose.r.r at metztli-it.com
Wed Oct 24 19:58:39 UTC 2007

--- "McDougall, Marshall (FSH)"
<Marshall.McDougall at gov.mb.ca> wrote:

> A while back we took delivery of several Dell 2950
> servers to update our
> hardware environment which supports our Ingres,
> Sybase and DB2 systems.
> Ingres 2.6 and DB2 were running on RHEL 2.1, Sybase
> was running on
> RHEL3.  We were hoping to be able to maintain the
> same levels software,
> but the new hardware is not supported by RHEL2.1. 
> This is where the fun
> starts.  I built up several RHEL4 servers and
> installed the Database
> systems on them and gave them to the DBA's to test. 
> They promptly came
> back and said that they were up to 7 times slower
> than the previous
> hardware platforms, with the exception of DB2.  I
> ran some OS benchmarks
> and they came back up to 7 times faster than the
> previous hardware.  We
> worked on various tweaks and tunes to the OS and
> DBMS to no avail.
> At that point we started to engage the
> vendors/support orgs for the
> various products.  Sybase could do nothing to
> improve performance on the
> RHEL4 server, so we tried RHEL5(or advanced platform
> or whatever they
> are calling it this week). The performance was just
> as dismal.  We ended
> up going back to RHEL3U9 to get the Sybase
> environment to an acceptable
> performance level. 
> Ingres is another story.  First they said try Ingres
> 2006.  It worked,
> but it has significant implications to our OpenRoad
> development
> environment, and as such is not really an option.  I
> went the same route
> as before with the various flavours of RHEL and it
> made no difference.
> Finally, I built a RHEL5 server, installed VMWare
> Server, and created a
> RHEL2.1 guest on that.  We now have performance
> where we want it.  The
> downside is that on my server with 8GB of ram I can
> only use 3.6GB for
> the VM. 
> My options as I see them now are; Install VMWare ESX
> and see if that
> buys me anything, or spend the time and effort to
> see if Xen will be of
> benefit.  The problem with the latter is that
> according to the doc RHEL
> 2.1 is not a supported OS on RH5.

Indeed, XenSource does not include the appropriate
modified kernel for RHEL 2.1 and, accordingly, is not
officially supported on XenEnterprise 3.2 or higher.

Notwithstanding, you can create an proper Linux kernel
for your RHEL 2.1 by installing the same into a
machine that has the CPU virtualization extensions
(i.e., hardware assisted virtualization).

Once you successfully install/modify your RHEL 2.1
under XenEnterprise in the above hardware assisted
virtualization environment, you can use the image on
older non-hardware assisted virtualization CPUs.

Before going to ESX, you may want to evaluate
XenEnterprise in price and performance.  Back in
version 3.2 of XenSource XenEnterprise, you could
allocate to an virtual machine up to 15GB of memory.

Disclaimer: Metztli Information Technology is an
Xensource Certified Partner.  
> So, after all this,  the gist of my post is; Has
> anybody successfully
> sparked up a RHEL 2.1 guest, using more than 4 GB of
> RAM, on a RH5
> virtual platform, or, has anyone installed Ingres
> 2.6 on a Linux 2.6
> kernel and made it perform at an expected level? 
> Thanks for reading
> this far.
> Regards, Marshall
> --
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Jose R Rodriguez

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