Cloud storage: Lower cost and increase uptime

Adaptec joins the Serial-ATA party today, with the launch at CeBIT of a set of SATA RAID cards at prices from £56. The two, four and eight channel cards are expected to replace low-end SCSI RAID controllers over time, as well as supplanting some of Adaptec's IDE (parallel ATA) RAID products.

"SATA is definitely ready from the point of view of easier cabling - its longer and thinner cables also bring better cooling," says Robert Helbig, an Adaptec field application engineer.

Helbig admits that at 150MB/sec, SATA offers no performance advantage over IDE, especially as the parallel-to-serial bridging technology in use today can limit real throughput to less than 100MB/sec.

He adds that even when SATA-2 comes along with 300MB/sec and extra features such as command queuing and drive hot-swapping, SCSI will still have the high end thanks to its advantages in areas such as error reporting and defect block handling.

In fact, SATA is everywhere at CeBIT. "Every single customer we talk to is moving to SATA for RAID. It ties in with the redefinition of how enterprises deploy storage," says Patrick Kevill of 3Ware, another RAID card supplier.

Cheap IDE or ATA-based RAID is finding favour because users are realising that not all of their data needs the protection and performance provided by high-end SCSI or Fibre Channel storage. As much as 75% is archived information or less critical data that could be shunted off onto cheaper storage.

Kevill says that a 3Ware SATA RAID adapter costs around 20% more than the equivalent IDE RAID card, because of the extra bridging chips needed, and that it adds £15 to £20 to the drive price.

(Western Digital CEO Matt Massengill turns this figure the other way around, by the way, saying WD is pitching its 36GB Raptor SATA drives at 30% below the price of an equivalent 36GB SCSI drive.)

Promise too has launched SATA boards, both basic four-channel RAID 0/1 models and intelligent versions with hardware RAID 5. Channel sales manager Sophie Sun says Promise is also supplying SATA chips to the likes of ASUS and MSI for integration onto mainboards.

However, there are still a couple of SATA caveats. Firstly, the connectors are weak and they really need the addition of a locking clip, warns Romain Cohen-Gonsaud, an area sales manager with disk enclosure supplier CiDesign.

And at the launch of EMC's first IDE-based Clariion storage boxes, senior vice-president and general manager Joel Schwartz robustly declared that SATA hard disks are not yet ready for EMC's customers.

"There are no SATA drives on the market today that we feel comfortable bringing to market," he said. There are reliability questions, he said, and some drives do not support hot-swapping. "We will move to SATA as soon as it meets our commercial standards," he added.

WD's Matt Massengill says this is partly EMC's innate conservatism, but acknowledges there is some truth there. "This is really brand new technology, and it will take time for everything to come together," he says. "Follow-on generations will be larger and more robust - we will see a surge of S-ATA subsystems over the next six months." ®

Steps to Take Before Choosing a Business Continuity Partner