IP-based storage is thoroughly enterprise-ready, claimed iSCSI specialist EqualLogic as it doubled the capacity of its high-end SAS (Serial Attached SCSI) storage box with almost no change in price.

The new PS3900XV array uses Seagate 300GB SAS drives to provide 4.8TB of capacity for around £40,000 - just £1,000 more than the 2.3TB version, said EqualLogic marketing veep John Joseph. He added that the latter's price will now be cut to £30,000. Bad news if you bought one recently...

EqualLogic is one of the few pushing iSCSI as equal-to or better-than Fibre Channel for high-performance large enterprise SANs. Joseph claims it can beat Fibre Channel partly because it virtualises and tiers the storage inside the array, and partly because it uses 15,000rpm SAS.

"Eighty per cent of SAS today ships inside servers, very few are using it in SAN technology," he said. Serial ATA is being used in SANs, he added, but for volume storage where reliability and performance are less of an issue. By comparison, the SAS drives his arrays use have a five year warranty and a 1.4 million hour MTBF.

It has been said that there's only two good times to buy a PC - six months ago, and six months from now - and the same seems to be true of storage. The cloud on the horizon is that putting more and more data onto each drive is eventually going to create a performance bottleneck, when the I/O rate demanded of it exceeds its read/write capability.

Joseph acknowledged that this point is not too far off, but said remedies are already in the works - in particular, a shift to enterprise-class 2.5 inch SAS drives.

"In 3.5 inch disks we have reached capacity levels where customers say 'I want more actuators' [read/write mechanisms]. So there is a trend towards 2.5 inch technology, with more actuators chasing the data," he said.

The smaller drives can provide half the capacity in a quarter of the footprint, although power and heat issues will probably restrict array builders to replacing 16 3.5 inch drives with just 24 to 30 2.5 inch models, he added.

"There is a price penalty too, that's why we're not racing to that technology," he said. Not only does a hard drive cost much the same to build whatever its physical size, but the smaller drives cost extra to miniaturise as well. ®