IMAGINE ONE THOUSAND thousand thousand thousand bytes. A terabyte, if you will. But more than just that—a milestone in storage capacity that hard drive manufacturers have been chasing for years. After more than a decade of living in a world of gigabytes, the bar has finally been raised by Hitachi’s terabyte-capacity Deskstar 7K1000.
Being first to the terabyte mark gives Hitachi bragging rights, and more importantly, the ability to offer single-drive storage capacity 33% greater than that of its competitors. Hitachi isn’t banking on capacity alone, though. The 7K1000 is also outfitted with a whopping 32MB of cache—double what you get with other 3.5″ hard drives. Couple that extra cache with 200GB platters that have the highest areal density of any drive on the market, and the 7K1000’s performance could impress as much as its capacity.
Has Hitachi achieved a perfect balance of speed and storage with its Deskstar 7K1000? We’ve tested it against nearly 20 competitors—including its closest 750GB rivals from Seagate and Western Digital—to find out.
When a terabyte isn’t
By now I’ve no doubt been heckled by someone insisting that the 7K1000 doesn’t actually offer a full terabyte of storage capacity. This person probably sounds like the comic book guy from The Simpsons, but don’t dismiss him. He has a point, sort of.
According to the International System of Units (SI), a terabyte consists of 1,000,000,000,000 bytes—10004, or 1012. Windows confirms that the 7K1000 delivers 1,000,202,240,000 bytes, which is more than it needs, so what’s the comic book guy on about?
Being first to the terabyte mark gives Hitachi bragging rights, and more importantly, the ability to offer single-drive storage capacity 33% greater than that of its competitors. Hitachi isn’t banking on capacity alone, though. The 7K1000 is also outfitted with a whopping 32MB of cache—double what you get with other 3.5″ hard drives. Couple that extra cache with 200GB platters that have the highest areal density of any drive on the market, and the 7K1000’s performance could impress as much as its capacity.
Has Hitachi achieved a perfect balance of speed and storage with its Deskstar 7K1000? We’ve tested it against nearly 20 competitors—including its closest 750GB rivals from Seagate and Western Digital—to find out.
When a terabyte isn’t
By now I’ve no doubt been heckled by someone insisting that the 7K1000 doesn’t actually offer a full terabyte of storage capacity. This person probably sounds like the comic book guy from The Simpsons, but don’t dismiss him. He has a point, sort of.
According to the International System of Units (SI), a terabyte consists of 1,000,000,000,000 bytes—10004, or 1012. Windows confirms that the 7K1000 delivers 1,000,202,240,000 bytes, which is more than it needs, so what’s the comic book guy on about?
Look a little closer, and you’ll see that while the 7K1000 does indeed offer over a trillion bytes, that capacity only translates to 931 gigabytes. For an explanation of why, we have to delve into the always exciting world of numerical systems. SI units are built on the same base 10 decimal system we’ve been using since grade school. Computers, however, use a binary base 2 system. So, while a kilobyte in decimal is 1,000 bytes, a kilobyte in binary translates to 1,024 bytes. A binary terabyte, then, is not 1,0004, but 1,0244, or 240.
Multiplying that out, a binary terabyte yields 1,099,511,627,776 bytes, which is why the 7K1000 falls short of a thousand gigabytes. The drive would actually need 1,024 gigabytes to achieve terabyte status in the binary world. This translation problem isn’t unique to the 7K1000, either. Virtually all hard drives advertise their capacities in SI units, so their actual capacities fall short of binary expectations.
Back in the day, the gap between decimal and binary capacity wasn’t big enough to ruffle feathers. Gigabyte drives were only “missing” 24 megabytes, and that was easy to swallow. However, higher capacities widen the disconnect between decimal and binary, leading the terabyte 7K1000 to pull up 69GB short. If you take out multimedia files, 69GB is probably more than enough capacity for what most of us have on our hard drives, so it’s hardly a drop in the bucket.
To help ease the confusion surrounding the PC’s base 2 binary system, various standards bodies are pushing a set of alternative binary prefixes. A terabyte would remain one trillion bytes, while “tebibyte” would denote 1,099,511,627,776 bytes. Needless to say, that hasn’t caught on yet. However, as growing hard drive capacities increase the amount of space “lost” in binary to decimal conversion, the tebibyte’s time may come.
The drive
Now that we have the math sorted out, it’s time to take a look at the Deskstar. Not that there’s much to see.
The 7K1000 looks like just about any other desktop drive. Only a couple of characters on the label serve as evidence of its monstrous capacity. Hard drives don’t need to score high on artistic impression, of course, but I’m continually surprised to see manufacturers wrapping their flagship products in the same generic skin as budget models. You’d think the reigning capacity king would have a little more flair, but there’s nothing to visually set the 7K1000 apart from other Deskstar models or even competitor drives.
Maximum external transfer rate 300MB/s
Buffer to disk transfer rate 1070Mbps
Read seek time 8.5ms
Write seek time 9.2ms
Average rotational latency 4.17ms
Spindle speed 7,200RPM
Available capacities 750GB, 1TB
Cache size 32MB
Platter size 200GB
Idle acoustics 2.9 bels
Seek acoustics 3.0-3.2 bels
Idle power consumption 8.1-9.0W
Read/write power consumption 12.8-13.6W
Native Command Queuing Yes
Recording technology Perpendicular
Warranty length Three years
To see what makes the 7K1000 special, you have to dig into the drive’s spec sheet. Terabyte capacity is obviously what makes this drive unique, but how it gets there is also important. The 7K1000 uses five platters to achieve its industry-leading capacity, perpendicularly packing an impressive 200GB onto each disk. These 200GB platters give the 7K1000 a higher areal density than competing drives that typically feature 188GB platters, and since higher areal densities can lead to better performance by allowing the drive head to access more data across the same physical area, the Deskstar is nicely set up for speed.
Copious amounts of cache should also help the 7K1000 in the performance department. Serial ATA hard drives typically come with either 8MB or 16MB of onboard cache, but the Deskstar packs a whopping 32MB thanks to a single Hynix memory chip. Hitachi didn’t add capacity to the Deskstar by turning the drive into a clumsy minivan, then; they built the hard drive equivalent of an Audi RS4 Avant.
With the 7K1000 breaking new ground in cache size and capacity, it’s almost amusing to see the drive hanging onto an old-school molex power connector. Power plug flexibility isn’t a problem, of course, and it may actually come in handy for those looking to deploy the drive in extremely large storage arrays, since power supplies typically only come with a handful of SATA power connectors.
A RAID array might be a good idea if you actually have a terabyte’s worth of data you’d like to store on the 7K1000. That’s a lot to lose, and despite the fact that Hitachi covers the drive with a three-year warranty, that warranty will only get you a replacement drive if yours fails—it won’t restore your data. by Geoff Gasior
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