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I am considering running a virtual machine on an external drive from a laptop. I understand that there will be a benefit to getting the vm off of the drive that the OS is on. Plus I could just use the space.

Given that scenario and assuming I don't want to spend more than a few hundred bucks, what combination of hardware will give me the best performing vm?

A fast hard drive vs. a solid state drive? USB vs. eSATA vs. Firewire (keeping in mind I'd need a Cardbus card for eSATA or Firewire)


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up vote 3 down vote accepted

You want eSATA for this; it will run at or near the speed of an internal SATA interface. Firewire's your second best choice. USB will work, but USB is never a best-performance option.

Check out this article for help finding a good CardBus card. It indicates very poor performance on some laptops' Cardbus controllers (note the Ricoh controller in the Lenovo and Dell X300). The combination of controller+card is the determining factor, so do some research on your laptop and see what cards are reported to work well with your controller.

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eSata is the way to go. Faster drives as well will help. As mentioned, there are some good cases with USB/Firewire adn eSATA so you can have a more versatile solution. Every test we have done showed the eSATA devcie to be faster running the VM under VMware.

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I'd say a solid state drive is out since you said you "could just use the space" and that would blow your budget of a "few hundred bucks". ESATA is by far the fastest connection, so get yourself that ESATA adapter and a nice big drive. The drive doesn't have to be a 10-15K RPM screamer. I run VMs just fine off a 7200 RPM, 1TB, ESATA Hitachi, no problem.

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I would recommend getting an external HD case that has a USB and an eSATA interface.

The cases are fairly cheap and can use any 3.5" SATA or SATA2 drive.

First, test the drive using the USB interface, if the performance is good enough for your needs (I doubt it won't be), you'll have saved a lot of money. If the drive isn't fast enough, you can always buy an eSATA card.

I doubt your needs will require the speed difference offered by the interface change. For that matter, I doubt most hard drives on the market are even capable of saturating the USB interface.

There's no point getting an eSATA setup for a drive that only has 100MB/second throughput.

The only way the USB interface wouldn't be fast enough is if you have many USB devices connected to the same bus. Because of how USB works (polling protocol with channels), extra devices can slow things down. If your laptop has other devices that use up a lot of USB bandwidth (a mouse and keyboard would not count), then I'd suggest going the eSATA route.

Firewire isn't very popular for external hard drives. I would avoid getting a Firewire setup.

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firewire doesn't have the bus problems USB does, which IMHO makes it much more preferable for external drives. it's true that there's not nearly as many options on the market, but aside from "slightly more expensive" i don't see a technical reason for not using firewire. – quack quixote Oct 30 '09 at 19:59

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