EqualLogic has a new PS3900XV drive array product using 15K rpm 300GB serial-attached SCSI drives. This tops out EqualLogic's range.

Seagate drives are combined with LSI Logic chipsets. It can scale to 4.8TB and sits above the PS3800XV box with 2.3TB of 15K rpm SAS storage. Below that is the PS3600X product with 10K rpm SAS drives. Below that is the SATA line of products.

The PS3900XV has redundant fans and controllers and hot-swap drives with two spares. If a drive starts to fail then it's switched out of service; a RAID rebuild initiated, and admin people e-mailed about it. This is a five nines level of reliability.

An EqualLogic IP SAN can be constructed from any of its PSnnnn arrays, either 7.2K rpm SATA or SAS, which can be 15K or 10K rpm.

Different drive array types can be combined in one IP storage area network (SAN) by stacking drive array boxes in a rack. This provides up to three tiers of virtualised storage in one SAN; a high-performance one, a mid-performance one, and a capacity-centric one.

The SAN can be divided up into different performance sections like this and apps assigned to each section (or pool) according to their performance needs. It might also be sub-divided into SANs for different departments. New arrays can be added on the fly to add more storage. Apps can be moved on the fly from pool to pool. Pools can be set up on the fly. It is all very sophisticated.

A nice touch is that customers buy one software license; they don't have to continually buy extra licenses to get extra functionality.

EqualLogic is convinced, with Gartner predictions and so forth, that SAS will take over from SCSI and provide the bulk of performant drive arrays with SATA providing the capacity arrays. Using IDC figures, about 20 percent of the enterprise market, the high-end performant products, will be Fibre Channel arbitrated loop by 2010; 75 percent will be SAS and SATA, and 5 percent will be FC and SAS at 10Krpm or less.

The PS3900XV is EqualLogic's second-generation SAS product. The existing PS3800XV outperforms EMC and NetApp arrays which don't use SAS drives yet. It outperforms them by supporting more users with fewer drives in Microsoft’s Exchange Solutions Reviewed Program (ESRP). The new box will be slightly faster because of the larger drives.

You can buy one for $67,000 and up. (£42,000 upwards in the UK.)