| Based on all the comments, I think one of your best options is to have a Raid 1 array dedicated to each VM. And also try to balance all the Raid 1 arrays across more then one controller.
If you stick with SATA, you could get two 8-port controllers, that would support 8 individual Raid 1 arrays, 16 drives total, 4 arrays per controller.
It will cost a little more price per Gb wise, but I think it will offer the most performance for the price. With each VM getting its own raid array, it will almost impossible for one VM to tax performance of another.
-John On Sep 15, 2007, at 9:11 PM, W. Chris Shank wrote: Yeah - but i want some disk redundancy. I think I'm going to use the VMs for some of our systems and stick with real servers for a few of the more important ones. I just can't have the super import ones getting hosed because some jackass decided to upload is MP3 collection.
----- Original Message -----
From: Toby DiPasquale <toby@cbcg.net>
To: Philadelphia Linux User's Group Discussion List <plug@lists.phillylinux.org>
Sent: Friday, September 14, 2007 8:28:41 PM GMT-0500
Subject: Re: [PLUG] help me design my server
On Fri, Sep 14, 2007 at 10:50:34AM -0400, 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.
Amazon works around this problem by giving each Xen instance a disk on its
own spindle. This may not work for you, but I'm just putting it out
there...
--
Toby DiPasquale
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--
W. Chris Shank
ACE Technology Group, LLC
www.myremoteITdept.com
(610) 640-4223
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