running multiple Workstation virtual machines on an NAS device

[MikeK2010]

I'm simultaneously running two guest operating system virtual machines on a single second internal hard drive using VMware Workstation 7.1 on a Windows 7 Pro x64 host with 8 GB of ram memory and an Intel Core 2 Duo E6700 processor. One guest (Win 7 x64) has all of my everyday used applications such as Microsoft Office and the other guest (Win 7 x32) is used strictly for surfing the internet and email. The host and one guest runs Norton Internet Security and the other guest runs Microsoft Security Essentials. About 85 percent of the ram memory is used when the host and both guests are running.

There are times when intense read/write activity, like running a full system virus scan, on one guest causes the other guest to slow to a crawl. I can hear the second internal hard drive chattering away. Would it work and would the performance of both guests be noticeably improved if each guest were installed and run on its own physical hard drive on a network attached storage device, such as a Synology DS411 Slim quad bay NAS device, set to JBOD and accessed via a gigabit Ethernet connection? Is there a better alternative as I can't install additional internal hard drives?

[Dennis_in_NH]

The worst case scenario is when both guests are doing intense disk operations -- both then compete for a single physical disk controller.

I'm betting most of the time, it's no big deal as each guest accesses the disk controller at times offset from the other with an occasional collision.

For the worst case scenario described above, having both guests VMs on their own disk would be better.  Each guest has their own disk controller so that contention issue is mitigated.  However, you are now having to access the disk over a network all the time and not just for the worst case.

Ideally, the GigE is fast and the network segment it's on is such that it only has traffic to the NAS.

Here's what I'd do: see if you can make it so that the heavy disk activity is scheduled at separate times to avoid the worse case scenario and see if that helps -- the goal being to keep the VMs on local disks and not over the network.  If this can't be helped, perhaps put one of the VMs on the NAS so at least you get the two disk controller advantage but only one of the VMs slows down.

Dennis