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USB disconnections in ESX 5.1


We have 2x USB drives (WD 1TB - same brand, no external PS, 1x USB connection per drive) which are connected to an SBS 2k11 VM via USB passthrough to a Dell R420 new server. Since we thought it's a physical server issue, we've upgraded from Dell R210 to Dell R420 - same issue.

The disks seem to be connected OK, until they're disconnected automatically from the server, at different times, usually during of Windows backup, but not necessarily.

I'm attaching 2 screenshots with the events.
ESXi version - 5.1 U2, Free Ed.

Your assistance will be more than welcome!
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3 Solutions
Dejan VasiljevicSys Admin and ProgrammerCommented:
Hi IT_Group1,

Can You tell us which version of VMware are You using?
Also USB storage drive can get disconnected under high network load, and also can "shut down" to power save it. So first go at power management/options and check there. Those are two common problems on virtual machines in VMware.
The USB at all have problems with VMWare, that is why they recommend VMware DigiAnywhereUSB. Also if You are running old VMWare there is a hotfix i think from since 2008 r2 for that, I guess they made it for the newer...

Please let us know if that didn't solved the problem so I/someone else could recommend anything else...
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It's not recommended to attach USB external drives to a VM, for backup. It's slow and unreliable.

The main objective why VMware implemented USB passthrough, was for devices such as USB "dongles" or "security keys" to be attached to VMware VMs, so servers could be consolidated, and virtualized....

unfortunately Admins, see "USB passthrough", and then go and hang off USB external disks for backup etc.... this was not the original design goal!

and has always been a non starter for most, and I wish VMware in hindsight, had never bothered with the implementation and support of it, and then Admins, would not treat it as a plug and play USB desktop!

I would recommend implementing a better solution, e.g. Network Backup to Western Digital NAS, World Boot Edition  drives.

We could look at the logs of the host, to establish may why....but it's probably just vSphere USB = "your milage with vary"

logs are here


Dejan VasiljevicSys Admin and ProgrammerCommented:
Yes Andrew is right, the main reasons why VMware was made is visualization, and if You use USB external disk attached to main machine it is missing the point...

And again the usb problems are common on VMware.

Also I would recommend to use some kind of network USB hub if You are willing to continue using those two drives.


IT_Group1Author Commented:
Thanks guys
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