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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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|
