Changed iSCSI ethernet adapter on postal

Tonight, I went ahead and changed the network adapter type on postal from flexible to enhanced, in order to be able to utilize Jumbo Frames on the iSCSI network connectivity to the SAN. To this, I:

• Made sure there were no active backup jobs
• Removed the persistent target connectivity to the SAN from the MS iSCSI initiator
• Disabled the iSCSI adapter on postal
• Shutdown Postal
• In the settings of the Postal VM, I removed the old iSCSI adapter, and added a new one: made sure to choose Enhanced adapter, instead of flexible. This would change the adapter name from "Network Adapter" to "Virtual Ethernet Adapter"
• Restart the server. The adapter should have limited connectivity due to the the iSCSI network not having a DHCP server.
• Reassign the iSCSI IP to the adapter (192.168.200.42) in the case of Postal.
• Reconnect to the MS iSCSI initiator, and reinitialize all the connections, and make sure that the "Bound devices" (last tab) shows the drive letter of the backup drive instead of a GUID of the drive mapping to the SAN. (The G: drive should also show up again on "My Computer"
• Go to the network adapter settings of the iSCSI network, and change the MTU from 1500 to 9000
• Now perform a ping test inside the iSCSI network with a big packet to make sure that the big packets are making it through all the way back to the SAN: ping -f -l 8972 192.168.200.252 (8972 seems to be the smallest packet that would go through on Jumbo Frames). You should get a reply.
  If you get "Packet needs to be fragmented by DF set", it means that the ping packet is too big to make it through on the MTU specified.

• This change was made on 04/06/2009 @ 12:20am
• Target: vmhost7 and postal