Re: VMs on external storage CPU overloading
On 8/1/2020 11:44 AM, Andrew Cater wrote:
That's the problem: An internal SSD is connected relatively directly to the
CPU. Almost all USB keys aren't optimised for fast data transfer other
than, perhaps, reading/buffering large single files. Running a VM means
constant read/write, constant update - it would be all the same as pushing
a CPU to constant use of a swap file/swap partition. It's massively
stressful on I/O - if you've a USB 2.x device, it transfers (very) slowly
compared to USB 3.x.
I have an USB 3.0 (USb port and USB key).
[For an illustration: even identical USB sticks will also vary: writing
2.7GB DVD images to a set of USB 2.0 sticks a couple of weeks ago: most of
them took six minutes, one took 35 - poor i/o and constantly swapping to
check (I used dd with the oflag=sync option - essential for data
integrity.) ]
The nearest comparison would be using a nice new NVME device. Inside a
laptop, in an M.2 slot - as fast as you like. Put it into an external USB
connected caddy - via USB 3.1 - for data transfer to another NVME inside
the laptop and it will be slightly to significantly slower. Same chip, same
laptop, moderated through a slower connection. That's the difference
between your VM on internal disk and your VM on USB stick
Okay, given that I can't increase the internal sise, my only way out is
an USB 3.0 that supports UASP or mounting a remote share by using sshfs...
I had understood Stefan's comment that it could be something else as well.
--
John Doe
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