vsphere 4.1 usb passthrough performance poor when vmotion support enabled - local Service Console doesn't see USB device
Ever since 3.5 up until and including 4.0 i have had certain clients with USB 2TB drives attached to the vSphere/ESX host and mounted in /mnt/usb/. This was used by vRanger 4.0 and above for repository for backups using SFTP. When i migrated to 4.1 i realized the i lost the ability to see anything attached to the ESX host via USB from service console. running fdisk -l simply showed nothing. However i quickly found out that i can now pass the USB through to the VM without loosing HA or vMotion support and so i did.
The performance was ridiculous! The backups that took 4 hours now ran 13 and that using Windows and 64KB block size!
Note: Reason i mention windows and block size is because backups that take 4 hours on USB attached to ESX formated with linux partitioning take far longer then ones ran against same USB attached to Windows physical server formated with 64KB block. This is tested all using same devices and many runs so you can take my word for it. Even though SMB transfer is supposedly slower.
I did some tweaking to make sure i didn't miss something but the time remained the same. I quickly realized that in order to be able to access a USB on another host once it fails over (keep in mind this is not the case the VM was on the same host as the USB) it means that there has to be added layer of communication to handle that which was in effect even when on the same host.
I went into the configuration and attached a second USB drive only this time i didn't check of "Maintain vMotion Support" or whatever it says there on that page. The backup ran and this time it completed roughly 2 hours. In fact exactly 4 minutes over.
If anyone knows of a way that you can still use USB drives inside the Service Console please by all means share. I have not actually confirmed this is removed in 4.1 from VMware however i did 4 upgrades and all lost the functionality and with the pass-through addition it only makes sense. This particular client is 100% on virtual platform so i can't attach it to physical box or want to deploy a dedicated server for pass-through device that doesn't have to fail over unless i have to.