The Terabyte Landmark: Hitachi Deskstar 7K1000

Storage
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DRIVE OVERVIEW


External appearance is identical to previous Hitachi drives we've seen.

The 7K1000 has a number of unusual features that set it apart from its competitors, but it's really business as usual for Hitachi. It's true that you don't see many five platter drives that spin down to save power in idle, but Hitachi's two previous flagship drives — the 7K500 and the 7K400 — did exactly this. In fact, the main thing that sets the 7K1000 aside from its predecessors is its size: Five 200 GB platters rather than five 100 GB or 80 GB platters in the older drives.

Acoustically, Hitachi's five platter design has tended to be bad news. With five times the moving surface area of a single platter drive, Hitachi's past drives have generated a lot of air noise. That's not to say the noise sounds bad — air noise is broadband and easy to ignore — but there's a lot of it. Hitachi's saving grace, and the reason we keep reviewing new drives, is the low RPM feature that spins the drive down to a lower rotation speed after 10~15 minutes in idle. The idea is to save power, but it has the wonderful side effect of reducing noise as well.

This feature is ideal for media archiving, as this usage pattern typically leaves the drive idling most of the time, so the drive spends most of its time in low RPM mode. This mode tends to be quiet enough that the drive is no longer a significant source of noise, but it still allows the drive to spin back up and operate at full speed on the rare occasions when it is needed.

The frequency graph below shows a recording of the 7K1000 in low RPM mode. We were able to determine the actual rotation speed in low RPM mode by finding the resonant peak — in this case 75 Hz. This tells us the rotation speed per second, since Hz = cycles per second, and the drive resonates at the rotation speed of its platters. Multiplying this number by 60 (seconds per minute) yields a number in RPM: 4,500. All things being equal, this should end up being at least as quiet as Western Digital's 5,400 RPM Caviar GP — but we'll see later whether this is actually the case.


The resonant peak in low RPM mode is 75 Hz, or 4,500 RPM.

Although the 7K1000 is a SATA-only drive, it is one of the last drives the retain the old IDE-style power connector in addition to the proper SATA power plug. Obviously, it is a bad idea to try plugging both in at once, but the legacy connector does have the advantage of retaining compatibility with old power supplies, making the drive a good choice for an old system revamped as a data center. It may also prove useful in any system with a large number of drives — few but the most expensive power supplies supply more than four SATA connectors, so a system with more drives than this requires adapters to power all the drives.


Hitachi still includes the old Molex power connector.

SPECIFICATIONS

The specifications below are specific to model that we examined. Capacity, cache size, platter number, interface, and even performance vary from model to model even within a single product line. Acoustics and power dissipation also vary depending on the number of platters in the drive; smaller capacity drives tend to have fewer platters, and tend to produce less noise and use less power.

Specifications: Hitachi Deskstar 7K1000 HDS721010KLA330
(from Hitachi's data sheet)
Capacity
1 TB (1,000.2 GB)
Cache
~32 MB (31,157 KB)
Disks / Heads
5 / 10
Interface SATA 3Gb/s
Spindle Rotation Speed
7,200 RPM
Media Transfer Rate (max) 1070 Mb/s (133 MB/s)
Latency
4.17 ms
Read Seek Time: Normal / AAM
8.5 / 14 ms
Write Seek Time: Normal / AAM
9.2 / 15 ms
Weight (max)
700 g
Power Requirements: Idle / AAM / Seek / Low RPM
9.0 / 10.8 / 13.6 / 4.5 W
Acoustics: Idle / AAM / Seek
2.9 / 3.0 / 3.2 bels (typical)

Hitachi's specs for the 7K1000 are long and detailed, with seek times specified for both normal and AAM seek conditions, as well as power specifications in five different power states (idle with the heads unloaded comes in at 6.9W, but is not listed in the table above for space reasons). Notable specs include a 32 MB cache (minus approximately 5% that is used for other purposes), a ~6 ms seek time difference between regular and AAM seeks, and a 4.5W power draw in low RPM idle.



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