The Constellation and Constellation ES models will replace Seagate's Barracuda ES enterprise drives. (Seagate will keep the Barracuda brand for desktop drives). Constellation drives are 2.5-inch small form factor (SFF) model SAS/SATA drives, with the first ones available in 160 GB and 500 GB capacities. Constellation ES 3.5-inch SAS/SATA drives will come in 500 GB, 1 TB and 2 TB capacities.
"We see the world moving to SAS even in the nearline space," says Barbara Craig, senior product marketing manager for Seagate's enterprise compute group. The SAS 2.0 spec improves the performance and scalability of SAS drives, with its main improvement a throughput boost from 3 Gbps to 6 Gbps.
The Constellation drives are expected to become available in March, with Constellation ES drives to follow in the second half of the year. A self-encrypting drive (SED) option will be available for Constellation drives in July.
With this product line, Seagate will also introduce a new power-efficiency feature called PowerChoice, which is a user- or OEM-controllable spin-down function.
PowerChoice has four levels. With PowerChoice 1 the drive is fully "awake." PowerChoice 2 "parks" the drive head away from the drive platter. PowerChoice 3 spins down the drive partially—in idle mode, Constellation drives on PowerChoice 3 draw 2.8 watts of power for SAS and 2.4 watts for SATA. PowerChoice 4 spins the drive down entirely.
Craig says users or OEMs integrating the drive into external storage systems will be able to set the spin-down level according to policy. For example, the drives could be set to go to PowerChoice 3 after 30 minutes of idleness, and to PowerChoice 4 during night or weekend hours.
Western Digital Corp. released a 2 TB SATA Caviar Green desktop drive last week, also claiming power-saving features. Western Digital's desktop drives spin slower than Seagate's Constellation drive. Part of the distinction between Seagate's enterprise offering and Western Digital's desktop offering is the rpm. Western Digital says the rpm of its drive is variable to maximize power savings, but generally less than 7,200 rpm.
As drive capacities increase, data protection becomes a concern because bigger drives can make failures more devastating. But John Rydning, research director, hard disk drives at Framingham, Mass.-based IDC, points out that to guard against failures, most disk systems now have RAID 6 capabilities to protect against a second drive failing while one drive is being rebuilt. Disk systems are also increasingly clustered or parallelized at the controller level for higher data availability.
"What we call 'capacity-optimized drives' like these," says Rydning, "are generally used first for second and third tiers of storage," which are usually redundant.
The advent of solid-state drives (SSDs) may also boost the market for larger, lower-tier drives for persistent storage. Some users say they're already looking for bigger, slower disk drives to handle ballooning archive capacity affordably. Others say that swapping out disk drives within existing disk arrays could be an affordable way to expand storage capacity without having to invest in a new chassis.