FunkyMike
Contributor
Contributor

Slow usb write performance

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I have recently deployed a Vmware ESXi version 4.1 server

I have a USB external drive connected to a guest VM for the purpose of backup.

I am finding that write performance is less than 50% of what a typical USB 2.0 external drive should get.

for instance i have a backup product that can usually get around 20MB/s write throughput to a directly connected usb 2.0 drive.

After doing a P2V on the same hardware i'm getting roughly 5-8MB/s of throughput vs what i was getting when using this as a physical machine.

Is this normal?

i'm also finding the throughput is erratic, it will drop down to 4MB/s then jump up to 10MB/s, jump back up to 7-8MB/s, etc.

where typically it was pretty consistent before.

thanks.

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AndreTheGiant
Immortal
Immortal

The actual USB virtualization is not designed to have a full 2.0 emulation.

Is more like a 1.1 speed.

You must use a NAS or wait for next vSphere version where maybe some enhancement are added in USB.

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro

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AndreTheGiant
Immortal
Immortal

The actual USB virtualization is not designed to have a full 2.0 emulation.

Is more like a 1.1 speed.

You must use a NAS or wait for next vSphere version where maybe some enhancement are added in USB.

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro

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TomHowarth
Leadership
Leadership

Andre, is correct, the USB emulation in vShpere is more akin to the 1.1 standard than the 2.0 standard.  sufice to say it works,  you would get better throughput by puting in another NIC card and backup your date over the wire to a USB device attached to your Desktop.

A better method may be to invest in a small portable NAS device if the purpose is to provide an off site capability for an SMB

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410