Internal Dell RD1000 performance

hi there,

We are using an internal Dell rd1000 (removeable storage disk) for backups on an ESXi 5 server in a branch office.

This is mapped through to a VM as a raw mapped disk drive.

When we connect this raw mapped disk to a windows VM we are getting poor write speeds (about 5MB/s).

As an experiment we connected the raw mapped disk to an Ubuntu VM and it writes at 30MB/s. (see attachment)

Can anyone explain the difference in speed? For support purposes we would rather use a windows VM but the performance is not good.

Cheers,

Huw