VMWare Server High Processor Usage (Disk I/O)

dellprocessraidsatavmware-server

I have a Dell Power Edge 6850 with 2 physical Dual Quad Core Processors and 24GB of Ram as our VMWare Host Server. We have VMWare Server (Old GSX) installed on this box and have 5 Virtual Servers (Guests) running. The Guest OS's are running off of a Dell MD1000 Array connected via Dell Perc 5e card. The drives are Satau 7200 RPM. All of these Servers run Windows Server 2003 R2.

The problem we are having is that when we read from or write to the VM (Guest OS) the processor usage jumps to between 80-100%. I used Process explorer and saw that Hardware Interrupts are what is jumping. I know this is a Disk I/O issue (I have used tools to verify the disk write backs) My question is where is the bottleneck occurring? Is it at the SCSI card, the Array or the drives themselves? I seem to think it is the drives, but does anyone know of a way to verify this? Any input would be appreciated.
Thanks,
Erik

Best Answer

Running ESXi instead of VMware-server will give you a HUGE performance boost. In either case I bet your second proc isnt licensed, IE, its not being used.

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Resizing RAID 1 Array on Dell PowerEdge with Perc 4/Di & Windows SBS 2003

I went through much pain with this, and the bottom line is that although the controller supports array expansion, Dell have disabled this in their Array Manager and they will not support it. If you replace the Dell driver with the LSI one (I think the controller is an LSI, though I wouldn't swear that it isn't an Adaptec) and use the LSI management software then you might be able to do it. However I would find this a scary business!

My solution was simply to create a new logical disk in the free space. This is completely safe and needs no reboots, though obviously it's clunkier having separate disks. If you really, really want a single partition then you'll have to backup then delete and recreate the array. Note that if your server has the Dell utility partition on it you need to be careful with partition imaging tools as you need to recreate the Dell utility partition or your server won't boot. I speak from (bitter) experience.

HP DL185 – very slow disk read speed

The RAID speed is poor but not extremely bad for such a setup. Now that you have a battery backup, you should enhance your ext4 parameters, particularly turn barriers off (they're unnecessary with a battery). Eventually you may want to try another filesystem, too (XFS is always the faster for sequential access).

edit: When the rebuild is done, you may want to tweak some settings, particularly read-ahead and queue depth:

blockdev  --setra 4096 /dev/sdXX
echo 512 > /sys/block/sdXX/queue/nr_requests

Try different values and see it makes any difference.

Best Answer

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