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I'm using a 27" iMac (i7, 8GB RAM) at work and normally run two or three virtual machines at the same time, which hurts the performance of each virtual machine.

I've learned on these forums the best way to increase virtual machine performance (aside from RAM) is to have them running on a separate hard drive from the one the OS is on. Of course with the iMac you can only have one hard drive and not even an SAS or solid state drive (well you could probably take it apart and put one in yourself but I wouldn't be permitted to do that).

That being said, do you think it would help to run one or more virtual machines from a firewire external drive (or a usb 2.0)?

Thanks for your input!

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up vote 1 down vote accepted

I have found that running VMs from a USB drive seriously hurts performance because of the bottleneck of the USB drive. I recently set up a USB drive and a Firewire drive in a RAID0 array and running Virtual Machines off that is far better than running them off just the USB drive was.

For improved performance, get a NAS device. The iMac has 1000BaseT ethernet so running VMs off a network share is also relatively fast. You can even make your own cheap NAS device with linux and a RAID array.

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cool thanks, i'll try this! – evan Apr 15 '10 at 23:09

I'm not sure that will help to an extent of better performance. They still have to use resources from your host machine. I find giving my VMs 500mb of RAM is plenty to just to do basic stuff, although, the new VM Fusion App performs a lot better when suspending virtuals - so maybe just customize your settings (more RAM for each) for each Virtual, and keep one open at any given time. Just my two cents.

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You might get a bit of a performance boost if the VMs are doing a lot of disk I/O. If you do try the external drive, stick with firewire. It should give you better throughput than the USB.

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