Dell's pimps 6gig SAS for DAS

Dell is adopting 6Gbit/s SAS for its PowerVault direct-attached storage (DAS) for servers with drives, enclosures and RAID controllers.

It says that this will effectively double the speed of its PowerVault DAS enabling it to keep up with the Nehalem generation of multi-cored and virtualised servers. The increased SAS speed is aligned to PCIe 2.0 speed as well.

There are three new models of the new PERC controllers. The H200 entry level and the H700 higher performance card are both internal controllers. The H800 is a high-performance external controller.

The H200 is the successor to the SAS 6/IR and adds more performance with the 6gig SAS, RAID 10 and support for up to 16 drives and for internal tape drives.

The H700 is a follow-on to the PERC 6/1 and, with its PCIe 2.0 support, delivers, Dell says, 35 per cent more IOPS performance. Howard Shoobe, Dell's senior storage product manager, talked of 35,000 IOPS rising to 50,000.

The H800, which appears to be a follow-on to the PERC 6e, supports a mix of 2.5-inch and 3.5-inch enclosures and has redundant I/O paths with load-balancing carried out automatically. The card has two ports which provide dual port performance, and redundancy should one port fail. Schoobe said this will help with Exchange 2010 and its focus on better I/O performance from DAS as opposed to storage accessed over a network. It and the H700 support self-encrypting drives.

There are two 6gig SAS enclosures; the MD1200 which is optimised for capacity and expandability, and the MD1220 which is the one to choose for more performance.

The MD1200 is a 2U box with a dozen 3.5-inch SAS II drives or a mix of 2.5-inch and 3.5-inch ones. It supports 7.2K (nearline), 10K and 15K hard disk drives, and 2.5-inch solid state drives, so its performance capabilities aren't that bad. It needs a PERC H800 controller and there can be eight MD1200s per server, for a total of 96 3.5-inch drives. Dell sees it being used for mainstream and capacity-intensive applications focusing on sequential I/O such as backup to disk, e-mail, and streaming media apps.

With this enclosure Shoobe says, you can have performance disks running in the same DAS system as capacity-focused disks for backup applications.

The MD1220 is the same enclosure filled with 24 2.5-inch hard drives running at 7.2K, 10K or 15K, or SSDs - Pliant 150GB ones as with the MD1200. Again it utilises the H800 and there can be a total of eight MD1220s for a max of 192 drives. The focus on 2.5-inch drives is to increase the spindle count compared to the MD1200 and and so up the IOPS rating. The intention is performance for I/O-intensive applications that focus on random I/O such as large databases, web serving, and heavy-load e-mail apps.

Shoobe said 6Gbit/s will become: "the fundamental storage backbone for our storage enclosures and many other storage products." The SSD capability is a near-term future, with Shoobe saying: "We are partnering with Pliant and shipping its SSDs in our blades today."

Dell is staying with 3Gbit/s SATA for low-cost and high-capacity drives, but SAS is the future for performance, not SATA, as it has better error-handling and better dual-port capabilities.

Dell is shipping the new PERC cards and the MD1200 and MD1220 enclosures now. The MD1220 is priced at £3,321.40 and the MD1200 at £3,011.40. ®