Re: [PLUG] VMWare performance tuning

["Mag Gam" <magawake@gmail.com>]

It really depends on the SAN. What kind of SAN is it? Are you doing a point to point connection, or fabric type connection? If using fabric, How many hosts are connected to the SAN switch? Are you planning to use MultiPath I/O (which is highly recommended).  How are the  LUNs assigned on the SAN array? Will or Can the SAN admin assign separate physical disks and zone them to your host? You need atleast 2 HBAs for SAN for redundancy, performance and scalability, so how many are you going to use? 

If you plan on using SAN, most likely you are already on a RAID5 group, so you don't have to mirror or stripe anything on VMware server or Clients. Also, SAN has the advantage of taking backups for you to an extent. 

It seems for your situation, you should probally consider getting more I/O paths (Fiber Adapters, or SCSI / SATA adapters) to spread your load across various disks...

Heh, I know more questions than answers :-)

HTH

On 7/29/07, W. Chris Shank <shankwc@acetechgroup.com> wrote:

The hardware is pretty good (dual quad core xeon, 4G ram). I was considering SCSI instead of SATA (i said USB - no SATA - DUH). I would consider off-loading some of the I/O to a SAN or another server, but how much of an improvement will it really give me?? I wonder if instead of RAID5 across 4 disks I should have 3 mirrors across 6 disks (2 for each mirror) and then put a couple of VMs on each disk mirror.

----- Original Message -----
From: Mag Gam <magawake@gmail.com >
To: Philadelphia Linux User's Group Discussion List <plug@lists.phillylinux.org>
Sent: Sunday, July 29, 2007 1:59:19 PM GMT-0500
Subject: Re: [PLUG] VMWare performance tuning

Chris:

This is a major pitfall of "virtua-LAZY-ation". Have you ever noticed vendors (Vmware, IBM, and Sun)  never mention this during their Roadshows?

Anyway,

here is how we tried to address the problem our environment (AIX APV), the same concepts should appl y:
Backups: Make sure you schedule your backups accordingly. Ie. Only 1 server is being backed up at a time
Use a SAN: Place your vmware images on a SAN and utilize  MultiPath I/O(MPIO) software such as EMC PowerPath. MPIO will loadbalance what adapters are busy and start sending data thru the other Fiber Adapter, this can increase performance by 50% percent. Keep in mind you need atleast 2 adapters.
Striping on Disks: Since you are using RAID5, you are already using this, so don't stripe again :-)
Mirroring: Make sure nothing is mirrored on the guest/client side. Your guest disks should NOT be mirrored, because they are already mirrored and redudant on the host end. This will be costly I/O
Placing data: Try to place your image data across various disks to you can spread the load.
Hardware: Buy new hardware :-). Try to buy more disk adapters (fiber or scsi), to spread the load.


HTH :-)

On 7/29/07, W. Chris Shank <shankwc@acetechgroup.com > wrote:

I have a VMWare server with several VMs on it. The system has a bit of a bottleneck at the disk IO level.  CPU performance is great, but if another VM starts hitting the disks hard, it really bogs down the other ones.  It has 4 USB HDD in a hardware RAID 5. Anyone have any suggestions on what I could do to improve the disk performance?

--
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

--
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