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."

Comments

Ethernet is NOT the right media

[SlashingComments]

Kill me if you like but Ethernet is NOT the right kind of media for this. Ethernet does not have "guranteed latency". It is not a real time thing--rather best effort thing. I will be happy to run this over a "fixed" latency media but not even think about doing it over ethernet. One of the reason I like firewire ... but I guess this is an apple thing and INTEL will do anything to kill it in the future or come up with other crap like USB.

Biased article

[Daniel Phillips]

HP's Graham Smith says:

"Without TCP/IP, it has no real error-recovery mechanism or guarantee that packets get delivered."

But that is wrong. There is error checking in the ethernet hardware and in the SCSI stack. It seems Smith needs to review the basic material, or should have at least read the introductory material. Perhaps the takeaway here is, managers should not be allowed to comment on technical material, or if they do, they should solicit advice from a practicing engineer first.

Smith also dumps on HyperSCSI's scalability, but as far as I can see, it scales exactly as well as any LAN, and for storage that's not bad at all. Besides, being 100% open source, implementing a repeater sitting on a routing box is entirely practical.

As far as Andre's comments go, the article should have disclosed that he peddles an iSCSI stack for a living. More power to him, I'm not criticizing his colorful comments or business scheme, just the journalist's failure to take note of this.

Now, my own opinion: I haven't tried HyperSCSI yet. I have it installed here and by rights I should have given it a thorough workout by now, but mea culpa. So little time, so much to do. Well I'll change that today.

From what I know so far: I like the idea of trimming away unnecessary layers. It's the kind of thing we do in Linux all the time. I like the fact that the whole stack is GPL. It doesn't bother me that disk drives themselves don't support the protocol and are unlikely to in the near future, because you have to put the disks in a box anyway, and that might as well be a Linux box presenting a HyperSCSI interface.

Personally, I think that HyperSCSI is going somewhere. So is iSCSI for that matter: the two protocols serve distinctly different target markets. iSCSI is where the money is because hardware vendors support it. HyperSCSI is where the joy of hacking is because it performs better and it's GPL. The thing is, they both present the same interface to the OS (SCSI) so they are interchangable. It's not an either/or situation at all.

You need to pay careful attention to any technique that increases performance without increasing cost.