For you demo warriors out there who try to get the maximum performance for your Hyper-V based demos, eSATA has been your path to maximum performance. If you only use a single drive attached to an eSATA port, you can quit reading, but if you are like me and want the best performance possible, you have probably invested in a 2.5” or 3.5” external portable cabinet that can take two or more drives.
These cabinets from makers like StarTech and AMS, have built in hardware RAID functionality that allow you to configure the dual drives in a RAID configuration without requiring a RAID card in your machine. Typically RAID 1 (mirroring) and RAID 0 (striping) are the two most common approaches in a dual drive case.
BUT, these external cases rely on a technology called Port Multiplication to see all the drives. You can go read the detailed description at your favorite web site, but basically port multiplication allows you to have multiple drives accessible through a single eSATA port. The catch is that the eSATA interface must support Port Multiplication.
This is where the issue is with integrated eSATA ports in laptops and desktop motherboards. They do not all support port multiplication…actually very few do.
I found this out the hard way recently. I purchased a new high end workstation class notebook that has an integrated eSATA port. the port I found out does not support port multiplication. If you attempt to connect an external case to the eSATA port and the drives are in RAID mode, the port will not be able to understand which drive it is talking to and the entire machine will slow to a crawl. Even if you attempt to configure the dual drives as JBOD, the ports will only see the 1st drive.
How do you deal with this issue? You use an ExpressCard with port multiplication support or use only a single drive case connected to the internal eSATA port.
Hope this saves you hours of headache…