Hitachi have announced a new high capacity and high performance hard drive in their line-up of solutions for enterprise servers, which offers a significant increase in storage capacity over existing 146GB and 300GB drives in that market segment

The new drive, the Ultrastar 15K450 offers a claimed 30% improvement in throughput rates of seek times of 3.3ms.

As this drive is intended primarily for front-line server use, it features either a 3 Gigabit per second Serial Attached SCSI (SAS) Interface or a 4 Gigabit per second Fibre Channel interface.

With a spindle speed of 15,000 RPM such a drive requires adequate air distribution, filtration and cooling. Aspects of this design requirement are visible in images of the drives internals, noticeably the number of air filters and air channels to manage air flow and air pressure. These features also provide a degree of damping which can counteract transmission of vibration from the very high speed rotating platters into the system chassis or transmit vibration to other disk drives.

Drive heads are parked in what Hitachi says is a patented ramp solution. When not in use, such as when the drive is off or in a low power state, the read/write heads are unloaded and moved over and parked in this ramp which protects the fine heads from damage improving drive reliability as well as protecting the disk platter and the users data which is contained on these platters by minimising the possibility of heads crashes when the drive is not in use, such as when the drive is being moved.

A head crash is termed as when a head [which is located on the tip of the metal arms visible in the photograph below] collapses and falls onto the disk platter, resulting in physical damage to both the platter and the head assembly resulting in data loss.

Disk platters may either be metal typically aluminium or glass with a magnetic coating, a technology which IBM (now Hitachi) pioneered.
Smaller platters are easier to make rotate faster, they also vibrate less, and also they are easier to stop and spin again because they are lighter so inertia is less

Those familiar with desktop 3.5 inch form factor hard drives may find the sight of the smaller diameter disk platters in this drive [and other high performance drives] a bit unusual. There are a number of reasons that smaller platters are used in high speed disk drives.

Smaller platters require less effort to reach their operational rotation speed than larger platters. This means that larger voice coils [the motor that spins the disk platters] are not required, and therefore power consumption and electrical circuit design are kept optimal.

Since this class of drives has an operational rotational speed of 15,000 RPM, vibration becomes an important issue to manage for the drive's own mechanicals and electronics, transmission through the system chassis and possible side effects on other components that are installed in the system chassis. Smaller platters, in addition to clever design of the HDD chassis aid in management of vibration.

Smaller platters offer faster seek times as the drive head does not have to physically move as far across the platter to access the desired data. In addition smaller platters are lighter so their inertia is less, resulting in quicker start stops and faster seeks. Fast seek times, especially average seek times are a requirement of server class hard disk drives, meaning data is located and accessed faster.

Full drive technical specifications are available at HGST's web site.

At time of going to press, unit pricing was not available. The 15K450 will ship this quarter.