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HyperSCSI Examined
An anonymous reader writes "Eugenie Larson of byteandswitch.com has published a brief article that reviews the HyperSCSI protocol, which like iSCSI allows for an IP based san. The twist of HyperSCSI is that it's opensource, and runs over raw ethernet, avoiding the overhead of TCP/IP. The article has some comments from early adopters of HyperSCSI, as well as some comments from top vendors in the iSCSI industry."
TCP is a layer above IP. Hence, the two are not mutually exclusive.
You can have "without the overhead of TCP/IP" and "IP based". All IP gets you is an address format and ARP type standards, it's not a lot of overhead.
If you look go to the MCSA site and look at the HyperSCSI FAQ, it does implement reliability and flow control, just not in the same manner as TCP.
The only technical negative side I can (at this time) is that because the implementation isn't over IP, you can't traverse a router. This usually isn't a problem but could cause some inflexibility in larger deployments.
The article does and abysmal job of covering this, but the homepage for HyperSCSI has a nice PDF presentation that covers just this topic. In short, it goes something like this: The SCSI protocols already provide error checking The HyperSCSI layer adds flow control and retransmits Ethernet provides certain other checks So, in total, you have the same reliabilty of iSCSI and FibreChannel with less overhead (i.e. significant overlapping of the protocols in terms of error detection/correction).
Oh, was that my outside voice?
USB maximum cable length: 5m
Serial ATA maximum cable length: 1m
Fiber Channel maximum cable length: 10,000 m