Hitachi Deskstar 7K500 500GB HDD
As fast as it's big?
Review We've never done a review of a single hard disk before, but this Hitachi drive justifies the attention. It's the first 500GB disk drive to hit the shelves - Hitachi has got its drive to market ahead of the likes of Maxtor and Seagate, who have announced drives but not yet shipped them. Half a terabyte in a single drive. Blimey! writes Leo Waldock.
Hitachi hasn't been very subtle in the method that it's used to achieve the landmark figure but instead has ganged up five platters and ten heads to achieve the 500GB, which tells us that each platter has a 100GB capacity. That's a surprisingly low areal density when you consider that Samsung's new SP2504C gets its 250GB capacity from a two-platter/four-head design. Hitachi has form in this respect as it released the five-platter 75GXP back in the days when it sold hard drives under the IBM brand and more recently it used five platters in the 400GB 7K400.
The result is a drive that looks very conventional from the outside. Should you be interested in such minutiae it weighs in at 692g, compared to 618g for the Samsung SP2504C. Hitachi has released the 7K500 in both SATA and PATA forms and, as you'd expect, the two drives are fundamentally similar. They both have a rotational speed of 7200rpm but the PATA drive has 8MB of cache compared to 16MB for the SATA model, and nominally the SATA drive has a much faster interface as it's SATA-II and rated at 3GBps compared to ATA-133. We can argue about the figures all day long but we all know that a single drive doesn't stress a 100MBps interface so the benefit over ATA-133 is merely theoretical. The business of switching to a Gbps rating (bits instead of bytes) for SATA is frankly annoying as there are eight bits in a byte yet every manufacturer is using a multiple of ten so 150MBps became 1.5Gbps instead of 1.2Gbps.
The 7K500 is Hitachi's first SATA-II design and the big news with SATA-II isn't the faster interface but instead centres on NCQ (Native Command Queuing) and Staggered Spin-up Support, though some SATA-I drives also support NCQ. NCQ is a pre-fetch technology that requires a suitable chipset, such as Nvidia's nForce 4, to speed up data transfer in a bid to get round the limitations of the mechanical device that lies at the centre of your otherwise solid-stated PC. Staggered Spin-Up enables the computer to turn on the various drives sequentially at start up to give your power supply an easier time. These are SATA technologies so it's a surprise to see that Hitachi includes a legacy four-pin Molex power connector on the back of the drive.
Take a close look at the power and data connector pins on a SATA drive and you'll see that they vary in length, so that the electrical connections are made in a specific order in order to protect the drive if you hot-plug it. By contrast, a legacy connector slams all four contacts into action simultaneously, increasing the chances of frying your hard drive circuitry unless you first shut the PC down.
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