EMC C-bit setting on the array needs to be enabled for VERITAS Volume Manager (tm) for Windows and VERITAS Storage Foundation (tm) for Windows Dynamic Multi-Pathing support
The C Bit
To manage the Multi-Pathing correctly, some hosts need to see identical devices, i.e. identical device serial numbers from each path. EMC arrays have something called the C bit which is a setting on the host interface director on the array. When enabled, the C bit zeroes out the last three bits of the device serial number, thereby presenting the same device serial number and hence, the same devices from both paths. In the above example, the host would be presented with 87010000 from either path.
EMC arrays present devices to the host via a device serial number, AABBBCCD, where: