Hitachi 7K400 400GB Hard Drive

FEATURES

Like the last Deskstar that we reviewed, the 7K400 features a number of low power modes that can be enabled, including the Low RPM mode that can reduce noise and vibration when the drive is not in use. In combination with the large 400GB capacity, this feature makes the 7K400 a good candidate for archival purposes.

Hitachi's marketing material lists "Robust Mechanical Enhancements" among the features of the drive, but doesn't go much further in depth. Digging a little deeper into Hitachi's website, I came across a PDF file entitled "Evolution, Accelerated" that detailed the mechanical differences between the 7K400 and the previous generation Deskstars. Four changes are noted: A new spindle motor, a load/unload ramp, an anti-rebound actuator latch, and something called Rotational Vibration Safeguard.

Like most other modern drives, the spindle motor uses Fluid Dynamic Bearing technology, which is a good sign for noise levels. What makes it special is the way the platters are mounted: The axle is anchored to the casing at both ends, not just at the base of the drive. This is supposed to reduce vibration, and is probably necessary to keep the five platters properly balanced. The reduction in vibration should help noise as well as improving data rates.

The load/unload ramp is derived from a common technology in laptop drives that is slowly finding its way across to the desktop market. The idea is that the actuator is mounted when not in use, which reduces power draw and prevents the possibility of a head crash (a bad thing) if the drive is jostled. The anti-rebound actuator latch extends this technology by locking the actuator in place once it is unloaded, preventing the actuator from accidentally being jarred loose when not in use.

The Rotational Vibration Safeguard is less a mechanical improvement than a software algorithm to compensate for the effects of external vibration on the actuator. The "mechancal improvement" is the inclusion of a sensor to detect vibration, but the bulk of the feature is the inclusion of this vibration data in the seek algorithms for the heads. This makes it less likely that read/write errors will be caused by external vibration, improving the reliability and performance of the drive. This feature is hardly unique to the Deskstar, but Hitachi seems to be one of the few manufacturers boasting about it.

TEST RESULTS

Our samples were tested according to our standard hard drive testing methodology. Our methodology focuses specifically on noise, and great effort is taken to ensure it is comprehensively measured and described. Performance is not tested, for reasons discussed in detail in the methodology article. For comprehensive HDD performance testing results, we recommend Storage Review, who have established a long reputation as the specialist in this field. We refer to Storage Review as a reference for many aspects of HDD performance. Their review of the Hitachi 7K400 may be found here.

Our test drives were compared against our reference drives, the Seagate Barracuda IV and Samsung Spinpoint P80, that are profiled in our methodology article. To get a good idea of where the drives in this review stand, it is important to read the methodology article thoroughly.

Two forms of hard drive noise are measured:

1. Airborne acoustics
2. Vibration-induced noise

These types of noise impact the subjective perception of hard drive noise differently depending on how and where the drive is mounted.

Both forms of noise are evaluated objectively and subjectively. Both the subjective and objective analyses are essential to understanding the acoustics of the drives. Airborne acoustics are measured using a professional caliber SLM with absolute sensitivity below 0 dB. Measurements are taken at a distance of one meter above the top of the drive using an A-weighted filter. Vibration noise is rated on a scale of 1-10 by comparing against our standard reference drives.

Ambient noise at the time of testing was 18 dBA. For the record, room temperature was 22~23°C.

The five platter design of the 7K400 makes it unlikely that this drive will challenge the low noise champion. The relatively high SPL measurement at idle bears this out: 25 dBA/1m is not especially quiet for a modern FDB drive. Its noise signature is fairly smooth however, with the only problem being an intermittent squeal from the electronic components. This squeal was piercing and hard to listen to, but it disappeared about halfway through the testing, so its uncertain whether it is a feature of the drive's design or just an unfortunate anomaly. Its high frequency means that it is highly directional, which means it may be less noticeable inside a good case where the noise is likely to be directed away from the user.

It is worth mentioning that the chirping head reset noise, which Hitachi has been notorious for in the past, was never heard in the 7K400. No unusual or unwarranted sounds disturbed the smooth idle noise of the drive.

Seek noise boosted the SPL reading by about 2 dBA/1m which isn't too bad for an increase in noise, but is fairly loud in absolute terms. The seeks are fairly sharp and contain a lot of high frequency noise. In comparison to the Samsung Spinpoint (Nidec) they seem more intrusive and less muted. AAM seemed to have very little effect on the noise level, although close listening revealed that there was more low frequency rumble and a slight metallic rattle that was absent before.

Drive vibration is about average, which is unfortunate since the average drive requires suspension to reduce vibration resonance. However, considering the number of platters, the average performance is fairly impressive; there was certainly potential to be much worse. It is quite likely that securing the axle to the top of the drive is instrumental in keeping vibration to this level.

Unfortunately, seek vibration is quite a different story. Seek noise is much louder when the drive is placed on the vibration box, with the primary noise being a hollow booming sound.

The power draw for the 7K400 was the highest of any drive we've tested, especially when seeking, where the separation between this drive and the next most power hungry was almost two watts, or 15%. It's probably a good idea to pay attention to the temperature of this drive, especially in a low airflow system.

The high noise and power draw meant I was looking forward to seeing how effective the Low RPM mode would be on this drive. So, I duly enabled it in the APM section of Hitachi's feature tool, and waited. And waited. And, no matter how long I waited, I never heard the heads park or the disk spin down. For whatever reason, the drive never entered Low RPM mode even after sitting idle for two or more hours — far longer than it took for the 7K250 to enter this mode.

At 25 dBA/1m, the 7K400 is louder than almost every other drive we've tested, with the exception of older, non-FDB drives. However, the extra capacity of this drive makes it worth a second look. A true comparison is not how this drives sounds compared to any single drive, but how quiet it is compared to the pair of 200 GB drives that is necessary to match its capacity.

A quick comparison was done with two of the 250 GB drives we had on hand: A Western Digital Caviar SE and an older Hitachi Deskstar 7K250. Individually, these drives idled at 22 and 23 dBA/1m respectively, but when measured together the SPL was 25 dBA/1m — the same as the 7K400 on its own. Subjective listening bore out this observation, though the pair of drives was slightly less pleasant to listen to because of a ringing overtone that could be heard in the background. This overtone was only heard when the two drives were brought close to each other (as they would be when installed in a case), and is probably the result of interaction between the two noise sources.

MP3 RECORDINGS

An MP3 recording of the 7K400 was made containing ten seconds of idle noise followed by ten seconds of seek noise with AAM enabled and ten more with AAM disabled. Keep in mind that the audio recordings paint only part of the acoustic picture; vibration noise is not recorded, and drives often sound different depending on the angle from which they are heard.

Hitachi Deskstar 7K400 HDS724040KLSA80 (Idle: 25 / AAM: 27 / Seek: 27-28 dBA/1m)

Dual Drives: Hitachi Deskstar 7K250 + Western Digital Caviar SE: (Idle: 25 dBA/1m)

Reference Comparatives:

Seagate Barracuda IV ST340016A (Idle: 21 / AAM: 23 / Seek: 25-26 dBA/1m)

Samsung Spinpoint P80 SP0802N, Nidec Motor (Idle: 21 / AAM: 23-24 / Seek: 25-26 dBA/1m)

Samsung Spinpoint P80 SP0802N, JVC Motor (Idle: 21 / AAM: 25 / Seek: 27 dBA/1m)

Nexus 92mm case fan @ 5V (17 dBA/1m) Reference

CONCLUSIONS

The largest drive we've ever tested has also turned out to be one of the loudest. In a single drive configuration, there are certainly much quieter choices. However, if all 400 GB are needed, the 7K400 is probably a better choice than two smaller drives. It's likely to be quieter, and two drives actually doubles the chances of a failure compared to one, although you'd stand to lose only half the data. At the moment, there is only one other 400 GB drive on the market, so choices at this capacity are a little slim.

As we've pointed out in recent forum discussions, however, external storage options abound these days — USB 2.0 for relatively undemanding transfer speeds, IEEE 1394 (Firewire) for faster transfer, and now, external SATA for bootable external storage that's as fast as any internal interface. Any of these external storage options can make a noisier drive like the 7K400 perfectly usable for silent computing. Just get a long enough cable and bury the drive in a closet where it can't be heard.

The mechanical improvements touted in Hitachi's marketing material should be good for reliability, although only time will tell whether they have the intended effect. Some of these features are available on competing models from other manufacturers, notably the head load/unload technology, but the engineering team behind the Deskstar line has a long history of pioneering improvementsthat get adopted industry-wide, so there is some substance behind Hitachi's marketing claims.

One thing that struck me during testing was the amount of time the drive takes to spin up. Hitachi claims that the drive's spin up time is 15 seconds, which may increase boot time if it is used as a system drive. Presumably, the spin up time to recover from Low RPM mode is also affected. Hitachi lists this recovery time as seven seconds.

Although we could not enable Low RPM Mode on our sample, the feature is listed among the drive's features. If the feature is working properly, this drive is an excellent choice for use as a secondary or backup drive that does not need to be accessed often.

The 7K400 has a niche for applications that require a lot of storage. For the average home user, this will be video files. Its capacity is both its biggest strength and its biggest liability. Its five platter design makes it suitable for uses where other drives are inadequate but is also responsible for the relatively high noise and power draw.

Many thanks to Hitachi Global Storage Technology for the Deskstar 7K400 sample.

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