Running a VM off a portable device

[kyle 3389]

so, I'm taking a college course on computer management. We use VMware allot in the class. Anyways, my professor told us we should NOT be running our virtual machines off of our portable hard drives / flash drives. But we should be transferring our VM to the desktop every time we want to run it.. Then save it back to the hard drive / flash drive when done.
Is this true? Is it not recommended to run a VM off a flash drive device? Why?
I myself have a portable SSD and it's very reliable. So I'd love to run my VM on that if its safe.

 

[Alabalcho]

There are two reasons it is not recommended (for off-the-mill USB flash drives):
- it is slow, even on USB 3.0
- it will wear down your USB key quite fast (they are not meant for continuous rewriting)

It might be different for SSD, though. If you are happy with the speed, go for it.

 

[kyle 3389]

There are two reasons it is not recommended (for off-the-mill USB flash drives):
- it is slow, even on USB 3.0
- it will wear down your USB key quite fast (they are not meant for continuous rewriting)

It might be different for SSD, though. If you are happy with the speed, go for it.

Thanks for the answer, what do you mean by wear down USB key?

 

[Alabalcho]

Flash memory can be written to limited number of times. Ordinary flash drives will become "read-only" (or even unreadable) if you continuously write to them.

SSD drives have controller which takes care of evenly wearing the drive, so this is of less concern for them.