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I've been using ESXi server for a while now. It's a pretty strong machine (i7-2600 + 16GB RAM), and I use it to run concurrently 5 VMs (Mostly Windows Server 2008 R2).

Most of the times, the VMs run just fine. However, my main issue is - when one of the VMs has extensive datastore usage (usually from applications left open, or extensive memory swap if virtual memory is running out), it makes all of the other machines extremely slow as well.

I tried using resource pools - but it seems like there is only CPU/Memory restrictions and not disk usage of some sort. (I'm using the free version of ESXi - don't know if premium versions contain this feature).

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Maybe it's using the swap if you are running out of ram. You could try disabling/lowering the swap to see if that's the problem. –  ponsfonze Jul 29 '12 at 6:44
    
I prefer not lowering the swap. If a VM needs swap - let it have it, I know that some of my VMs do need swap. I just want it to use it in a 'slowed' manner. So every VM would be limited to a fifth of my disk power if that's possible. –  Roy Reznik Jul 29 '12 at 6:47

1 Answer 1

up vote 3 down vote accepted

According to this kb you can:

To manually configure disk I/O limits for a virtual machine:

  1. Power off the virtual machine in preparation for changing the configuration parameters.
  2. Locate the virtual machine in the vSphere Client inventory.
  3. Right-click the virtual machine and select Edit Settings.

Click the Resources tab. Select Disk, and enter the desired IOPs value under Limit - IOPs for each disk. By default, this is set to Unlimited. Start the virtual machine. The virtual machine I/O is limited to the specified values.

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Thanks. Great answer. Just a small follow-up, do you know how I can calculate the maximum IOPs for my disk? (So I'll know which value I want to put there...) –  Roy Reznik Jul 29 '12 at 7:29
    
You will need to refer to your disk's manual for that, normally it's written down in there. –  Lucas Kauffman Jul 29 '12 at 7:31

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