Sassy to scuzzy to sass - I/O with Mark & Hal - Column

Computer Technology Review, Feb, 2003 by Mark Ferelli, Hal Glatzer

Mark: There wasn't much meat on the bone at the Server I/O Conference in January.

Hal: Everyone's on a diet these days, what with the economy in the tank.

Mark: True, but it doesn't seem to have stemmed the tide of new players coming into the storage space.

Hal: Such as...?

Mark: Z-Force put together something so intuitively obvious that one had to wonder why nobody'd done it before: an NAS array.

Hal: Wait a second. Isn't that just a glorified Snap appliance?

Mark: Nope. Z-Force's entry includes switching technology. You know that, in order to go from server to storage in a SAN, you go through a SAN switch. So, to create a NAS array, Z-Force uses something similar to a RAID controller. Of course, the new Snap appliance was on display, too.

Hal: Tell me about that.

Mark: Snap is a recent spinoff from Ouantum-

Hal: Which we covered last year.

Mark: Yes. They've taken over all of its NAS appliance business. And with any kind of luck, they'll pick up some of the business that Maxtor has since abandoned, too.

Hal: That sounds pretty routine--one company feeding from the trough after another has left. There must have been something truly exciting at the conference.

Mark: For me, the hottest announcements were the developments in Serial-Attached SCSI.

Hal: I'm not so sanguine about SCSI as I used to be. As you know, the popularity of HDDs using ATA is enormous and growing. ATA is less expensive, and the performance is high enough for most installations and most apps.

Mark: Yes. But now what we're seeing is a progression from "sassy" to "skuzzy" to "sass."

Hal: Very funny! Better explain that.

Mark: Surely we all remember our history lessons! First there was Al Shugart's protocol: the Shugart Associates Systems Interface, or SASI, for short. Then came the industry-standard Small Computer Systems Interface, which is SCSI. Well, now there's Serial-Attached SCSI or just plain SAS.

Hal: We'll remember it now! How does it work?

Mark: Under the Serial-Attached SCSI approach, which includes a re-working of the connector technology, it should be possible for an integrator to select between high-performance SCSI drives and lower-performance serial ATA drives, while still basing the entire array on traditional SCSI connectivity.

Hal: So, does that mean users wouldn't have to change physical connectors to change source drives?

Mark: Yes.

Hal: Then, I'm confused. Wouldn't that add cost and unnecessary complexity to the array? Why not just stick with one flavor of connectivity or the other? Go for economy with ATA. Or go for performance with SCSI--especially now that there's iSCSI available. Which reminds me: Addison-Wesley's just published a new book on that subject, by 35-year IBM veteran John Hufferd. It's called iSCSI: the Universal Storage Connection. I'd question the use of a headline word like "universal," in any storage context, but the book itself is a solid, well-presented handbook for anyone who's got to be up on the subject.

Mark: Well, in resolving the conflict between ATA and SCSI, the idea of SAS is the old-fashioned one: Let the customer decide!

Hal: So, what about the complexity? Isn't it inevitable? And how does SAS address it?

Mark: That very question came up often, at the conference.

Hal: Ibet it did!

Mark: The issues involved in managing complexity were common threads running through practically every session that wasn't vendor-specific.

Hal: And was there a consensus?

Mark: Most of the presenters agreed that storage software isn't yet capable of coping with the complexity: That the state-of-the-art is still not up to the task.

Hal: No surprise, there. But isn't this what "virtualization" is supposed to overcome?

Mark: It turns out that "virtualization" is only part of the solution. It masks the complexity from the user with a layer of abstraction.

Hal: So, let me get this straight: It overcomes complexity by adding another layer of complexity.

Mark: I said it wasn't the whole answer!

Hal: So, does anybody have what radio commentator Paul Harvey calls "the rest of the story?"

Mark: No. It's still unresolved. Remember the old saying: The solution is in the search?

Hal: I think it's still in the soup. And it's not yet "duck soup."

Mark: Let's see if our readers have a fresh ingredient to toss in. If you think virtualization will carry the day, email me at: mark_ferelli@wwpi.com

Hal: And if you think we've still got a long way to go before complexity turns into simplicity, email me at: hal_glatzer@wwpi.com