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Computer Parts: Hitachi 750GB hard drives

The terabyte barrier has already been broken by Seagate with the introduction of the slightly thicker (12.7mm) 2.5” 1.5TB external hard drives. Now it’s time for Hitachi to announce something new: Hitachi Travelstar 5K750 and the Travelstar 7K750.

Both hard drive families are based on a two-disk design, featuring a maximum of 375GB/platter data storage. Drive thickness is only 9.5mm, so all these new hard drives will fit in any laptop (with a SATA interface).

The Travelstar 5K750 Family consists of 5400RPM drives with 8MB of cache. It seems that manufacturers intentionally reduced the size of cache, because not so long ago they were racing to increase it to 16MB, 32MB or 64MB to improve performance. Power consumption on the other hand was significantly improved, these 5400RPM Hitachi drives consume only 0.5Watts in idle and 1.4Watts while reading or writing. This also means that they can be used in any external 2.5” HDD rack, receiving power from only one USB2.0 port. 2.5” hard drives are designed for travel, for use in laptops and external racks, but they really have very limited shock resistance while turned on. Turned off they survive shocks up to 1000G/1ms, this is good news for shipping companies, but the end user rarely benefits from this feature.

Travelstar 7K750 hard drives are performance-oriented. They spin at 7200RPM and feature 16MB of cache (still a very small amount considering the other performance limitations of laptop hard drives). Power consumption is very impressive, only 1.8Watts in read or write mode. The SATA 2 interface is absolutely unnecessary, because the maximum transfer rates of these drives doesn’t exceed 100MB/s, but when more drives are used in RAID mode it really makes a difference to have the latest bus technology. Some laptops (or mobile workstations) have up to four hard drive bays, so configuring four 750GB 7200RPM drives in RAID0 mode will result in a very high performance 3TB unit, while consuming only as much energy as one 3.5” desktop hard drive. Fluid dynamic bearing is a technology frequently used in hard drives to provide very silent operation. The downside of this technology is the relatively short lifespan; usually this is what gives out first in a hard drive.

Although it shouldn’t be too difficult to bypass or decrypt, these new drives (Travelstar 7K750 family) feature the SED (self-encrypting drive) technology. It’s aimed at government and financial institutions where high-risk information is often stored. The SED feature encrypts all data on the hard drive without burdening the CPU with it, because it’s done locally in the hard drive, so when the laptop is stolen theoretically the thieves won’t have access to the hard drive’s contents. Seagate was the first to introduce this technology to its newest hard drives, but clearly it will be adopted by other manufacturers too, figuring that the lack of it will reduce sales.

There’s one more thing about these Hitachi hard drives that makes them practical: the 4Kilobyte physical sector. While in the file system you could set sector size to 4K before, it was translated to 512b size when data was written to the drive. Now they realized that 4K is the way to go, because it reduces the space needed for CRC check, thus leaving more space available to the user.

Hitachi Travelstar 5K750 drives will be available in November with a $129 (suggested) price tag, while the 7200RPM drives (Travelstar 7K750) will ship only in 2011.