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Re: [PLUG] help me design my server
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You might want to consider using raw volumes, rather than files on the
host. Not only is it more space efficient, it should help with reducing
your disk I/O.
--Matt
On Fri, 2007-09-14 at 12:43 -0400, W. Chris Shank wrote:
> The VMs use disk files on the host filesystem. So the host talks to
> the SATA controller directly.
>
>
> ----- Original Message -----
> From: John Von Essen <john@essenz.com>
> To: Philadelphia Linux User's Group Discussion List
> <plug@lists.phillylinux.org>
> Sent: Friday, September 14, 2007 12:17:10 PM GMT-0500
> Subject: Re: [PLUG] help me design my server
>
> How does the VM access the storage?
>
>
> Not sure which kernel context talks to the SATA controller. But
> whichever kernel does that, thats the one that needs more ram so it
> can do caching on the IO requests being sent to the controller.
>
>
> -John
>
> On Sep 14, 2007, at 11:41 AM, W. Chris Shank wrote:
>
> I'm going to do that - but there isn't really any swapping on
> the host OS. Or are you saying more virtual RAM on the VM?
>
>
> ----- Original Message -----
> From: John Von Essen <john@essenz.com>
> To: Philadelphia Linux User's Group Discussion List
> <plug@lists.phillylinux.org>
> Sent: Friday, September 14, 2007 11:32:13 AM GMT-0500
> Subject: Re: [PLUG] help me design my server
>
> Forget to mention, increasing RAM will make a significant
> difference. The kernel caching will alleviate alot of disk IO
> since those requests will be processed right from cache.
> Performance of increased memory is somewhat dependent on how
> you use your disk, i.e. heavy reads of common data vs random
> data.
>
>
> -John
>
>
>
>
>
> On Sep 14, 2007, at 11:28 AM, John Von Essen wrote:
>
> Chris,
>
>
> The SATA arrays will always poor IO performance in
> environments like yours. I have some experience from
> going through issues with an 8-core Postgres server
> with heavy disk IO problems.
>
>
> SCSI Raid will be better, especially if you have alot
> of spindles. Raid 10 instead of Raid 5 etc.,. And if
> you split it up across both channels of a dual channel
> card or spit it across multiple cards, that will help
> too. Problem is size limitations of SCSI raid 10 due
> to the numbers of drive slots in most external
> enclusores. 14-bay enclosure with Raid 10 and 146Gb
> drives will give about 1Tb. I wouldn't recommend using
> the 300Gb scsi drives. Smaller the drive, the better.
>
>
> Eventually, SCSI will also break down. When that
> happens, you'll start to need a Fibre-Channel attached
> SAN, one specifically designed for high IO
> environments. The EMC Clarrions are getting a little
> better in price, but still pricy when compared to SATA
> arrays.
>
>
> You may never need the EMC-level performance, so SCSI
> Raid with alot of spindles and good HBA controller
> management might do the trick for awhile.
>
>
> -John
>
> On Sep 14, 2007, at 10:50 AM, W. Chris Shank wrote:
>
> I need to spec-out and architect another
> VMWare and/or Xen VM host server. Currently I
> have one with 8 cores, 4GB ram, and 1.5TB HDD
> as 4 500GB SATA with hardware raid5. We are
> starting to hit the wall with this setup
> running 5 VMs on it. Particularly, it seems
> the HDD I/O is the bottleneck. If one VM hits
> the disks hard it makes the others pretty much
> useless.
>
> So I have a budget to get another honking
> server. I'm confident the quad-core Xeons with
> the vm extensions are sufficient. I'll go
> ahead and bump the RAM to 16G too. The area
> I'm most concerned with is the disk I/O. I'm
> thinking that instead of one big RAID5, I'll
> pair smaller drives - so i'll have 4 sets of 2
> 250G SATA mirrors. Then direct it so that 2-3
> VMs are on each raid. Or should I go SCSI and
> keep one large RAID5?
>
> So if you had the $$, what would you get and
> how would you configure it.
>
> Thanks
>
> --
> W. Chris Shank
> ACE Technology Group, LLC
> www.myremoteITdept.com
> (610) 640-4223
>
> --------------------------------
> Security Note: To protect against computer viruses,
> e-mail programs may prevent sending or receiving
> certain types of file attachments. Check your e-mail
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> ___________________________________________________________________________
> Philadelphia Linux Users Group --
> http://www.phillylinux.org
> Announcements -
> http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion --
> http://lists.phillylinux.org/mailman/listinfo/plug
>
> John Von Essen (john@essenz.com)
> President, Essenz Consulting www.essenz.com
>
>
>
>
>
>
>
>
> ___________________________________________________________________________
> Philadelphia Linux Users Group --
> http://www.phillylinux.org
> Announcements -
> http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion --
> http://lists.phillylinux.org/mailman/listinfo/plug
>
> John Von Essen (john@essenz.com)
> President, Essenz Consulting www.essenz.com
>
>
>
>
>
>
>
>
>
>
> --
> W. Chris Shank
> ACE Technology Group, LLC
> www.myremoteITdept.com
> (610) 640-4223
>
> --------------------------------
> Security Note: To protect against computer viruses,
> e-mail programs may prevent sending or receiving
> certain types of file attachments. Check your e-mail
> security settings to determine how attachments are
> handled.
> ___________________________________________________________________________
> Philadelphia Linux Users Group --
> http://www.phillylinux.org
> Announcements -
> http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion --
> http://lists.phillylinux.org/mailman/listinfo/plug
>
> John Von Essen (john@essenz.com)
>
> President, Essenz Consulting www.essenz.com
>
>
>
>
>
>
>
>
>
> --
> W. Chris Shank
> ACE Technology Group, LLC
> www.myremoteITdept.com
> (610) 640-4223
>
> --------------------------------
> Security Note: To protect against computer viruses,
> e-mail programs may prevent sending or receiving
> certain types of file attachments. Check your e-mail
> security settings to determine how attachments are
> handled.
> ___________________________________________________________________________
> Philadelphia Linux Users Group -- http://www.phillylinux.org
> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
___________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
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