Hitachi has developed a 450GB enterprise-class hard drive with speeds of 15,000 RPM, matching Seagate for the highest-capacity hard drive at that speed level.

15,000-RPM drives are competing for customer demand with 7,200-RPM drives, which have slower speeds but offer up to 1 terabyte of capacity, more than twice that of 15,000-RPM devices, says IDC research director for hard disk drives John Rydning.

Drive manufacturers Hitachi, Seagate and Fujitsu have run into technological barriers slowing the storage growth for high-performance drives, he says. (Compare storage products.) Typically, the vendors double capacity every 18 to 24 months, but in this cycle they are instead moving from 300G to 450GB.

"The reason is that the 600GB products are forthcoming, but may not hit that 24-month window," Rydning says. "It's just getting challenging to do the higher-capacity products at 15,000-RPM. If you can do a 450GB in between, you alleviate some of your customers' storage growth pains."

Fujitsu's highest-capacity 15,000-RPM drives hold 300GB, according to Rydning. Seagate began shipping its 450GB drive last month. 

Hitachi's 450GB drive, the Ultrastar 15K450, will begin shipping to resellers this quarter, Hitachi announced Wednesday. Then OEM customers will implement the drives into their storage systems and make them available to end users.

The growth rate of storage capacity in the 15,000-RPM drives is slowing for several reasons, says Dean Amini, director of Hitachi's enterprise market & strategy group. Performance specifications are significantly more stringent, making it difficult to increase capacity, he says. Also, the read/write head moves over the disk at very fast speeds in the 15,000-RPM drives, which makes it harder to read data at great densities. The 7,200-RPM drives read data slower and can therefore gather data at higher density, Amini says.

The Ultrastar 15K450 has an average seek time of 3.6 milliseconds, and "fast rotational speeds [that] reduce average latency time to 2 milliseconds, enabling customers to access data more quickly and efficiently," Hitachi states.

The drives will ship either with 3Gbps Serial Attached SCSI, or 4Gbps Fibre Channel interfaces.

Hitachi recommends using the drives for mission-critical applications that serve multiple users, including online transaction processing and intensive database queries.