SAS 6Gbps adapters finally hit the road

ALTHOUGH IT SEEMS  to have taken an eternity, SAS 6Gbps adapters are finally out. LSI is launching a bunch of products while claiming several key marketplace victories.

The biggest news is of course the products, and the short story is that LSI has all its  major lines in 6G SAS now. The most interesting ones are the SAS2008 Controller IC, SAS2108 Raid On Chip (ROC) IC, a 36 port SAS expander IC, interposer boards and Storage Processor ICs. They also have Host Bus Adapters (HBAs) and RAID cards. If they don't build it, LSI will sell you the chips to build it with.

A few months ago, LSI announced that it had six tier-1 OEM wins, basically all the big boys that matter. Today the firm announced that Supermicro is on board, so that brings the tech to a majority of the white box server vendors as well. If you are interested in SAS 6Gbps, you will be able to buy it just about everywhere in a few months.

If you are wondering why you should care about SAS any more, with SANs and other net-bound technologies all the rage, there are two big reasons. The first is latency, with directly-attached storage, there is little or no contention for a spindle from another machine and things that rely more on I/Os than raw bandwidth really benefit. Databases and Exchange virus circulators speed up a lot from fast local storage.

The other thing that SAS brings is storage capacity. You can get drives up to 600G now, paltry compared to the 1.5TB SATA beasts out there, but SAS has high spindle speeds, and blistering random access times. Now, you can get 36 port SAS 6G expanders, so a single 8-port adapter can host over 250 drives. This may not be sane, but it is a lot cheaper than a SAN, and will support multi-pathing for failover. DAS is far from dead.

With all of this in mind, LSI is claiming to have leadership in SAS shipments. In 2004, they edged out Adaptec in unit sales, and haven't looked back. Given the partners they have for the next generation, and being first out of the gate with product, it doesn't look like they will relinquish that position any time soon.

One last thing to ponder, SAS 6G and SSDs. No one has been really making noise about this, but the big bottleneck in the SSD world is SATA controllers. Once you get a few SSDs RAIDed, you become painfully aware of the limits of your controller. SAS 6G might very well break that bottleneck, we shall see shortly when the boards hit the market.

Overall, the speed doubles, latency drops, and everything just gets faster. 250 or more drives per card if you want to push it, and high spindle speed on top of that. The icing on the cake is backwards compatibility. µ