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Three Generations Compared: Why Storage Density Matters

Three Generations Compared: Why Storage Density Matters

Increased data density typically results in better throughput, but it also allows hard drive makers to create drives that require fewer physical components to reach popular capacity points. The effect is more value and lower cost for the end-user. After multiple analyses with Samsung drives in 2009, we grabbed the last three generations of Hitachi Deskstar 7K1000 drives to look at the effects of recent progress. Get ready to see the new Deskstar 7K1000.C do battle with the 7K1000.B and the original 7K1000.

500 GB per Platter

Competing hard drives, such as the Western Digital Caviar Black and Green series, have already been utilizing similar storage densities, cramming 500GB onto a single 3.5” platter. Samsung’s Spinpoint F3 and the Seagate Barracuda XT are other examples. However, these product families cover the full capacity range from 160GB or 250GB entry-level drives up to 2TB capacity points. Hitachi’s naming approach is different from its peers because the "1000" in the 7K1000 family notes a 1TB capacity.

Which is the Better Strategy?

Samsung and WD each offer two product lines that cover all capacity points, but differ in positioning. There are green drives that spin at 5,400 RPM and performance drives at 7,200 RPM. Typically, there's even a third line with drives qualified and validated for 24x7 server applications. Do we really need so many options? Yes and no. Hard drive makers feel it's necessary to address all market segments. Geeks can find their perfect hard drives from the Barracuda, Caviar, Deskstar, Spinpoint, and Black, Green, EG, LP, or XT models. More mainstream consumers are likely to find this all bewildering, which might explain why Seagate has been reducing its variety, offering the Barracuda XT at 2TB and 7200.12 at 1TB only.

While Hitachi has a product line that offers high capacity SATA storage for business environments, it lacks a power-efficient product line at lower RPMs. Instead, the high-capacity drives are based on a massive five-platter design. All mainstream Hitachi drives, however, originate from a different product line that has so far been limited to 1TB. Unbelievably for many enthusiasts, most 3.5” hard drives sold today are still below this capacity point.

Going from the five-platter 7K1000 to the three-platter 7K1000.B introduced a 20% boost in performance while similarly increasing efficiency. Can the two-platter 7K1000.C continue to improve along these lines?

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  • -9 Hide
    joex444 , February 27, 2010 5:24 AM
    So fewer platters = less energy and higher transfer rates and higher latency.

    One could guess that with elementary physics. In fact, it is obvious this should be the case. Way to earn your money, asshat.
  • -3 Hide
    LaloFG , February 27, 2010 7:51 PM
    Nice article, I'm tempting to buy a pair of this hard disk.

    It's true that high density equals high failure ratio? It is too risky use these disk (with high density) to hold data compared with old disk?

    (I have two 500GB HDs from ~2006 and still they are working flawless right now)
  • -2 Hide
    davidhbrown , February 28, 2010 11:23 AM
    You write that fewer platters yield better performance. I can certainly see why that would lower cost. But given that each surface has its own r/w head, shouldn't drive manufacturers be able to use the platters in parallel, sort of like RAID 0, to boost performance? Is this already done to some degree (maybe the two surfaces work in parallel), or is there some reason beyond controller cost and lack of market demand preventing this.
  • -1 Hide
    candide08 , February 28, 2010 12:40 PM
    Perhaps it should have been written that "for the same capacity (GB) fewer platters yield better performance." This would be because the data density (bits per sector/track) would be higher. "Smaller" bits take less time to read - with newer generation disk heads.

    There are also huge differences in capacity between generations of disk RW heads and newer heads tend to used with disks that have fewer platters, at least initially.

    Some RAID controllers do exactly as you say. The theory is that if the data is stored on 'cylinders' (same sector different platter) the disk arm will need to move less to transfer the data, saving time.

    This is classic main-frame disk array architecture, now easily available on high-end PC disks, some SAN's and some raid controllers. The more disk heads the faster the performance with these arrays.

  • 0 Hide
    wuzy , March 2, 2010 3:41 PM
    7200rpm 1TB drives are best suited for nearline storage or worktation usage if put into RAID array, where performance at shallow depth queue is more essential and is not heavily loaded 24/7. So the conclusion of this article makes sense, it's about $/GB while still maintaining 7200rpm needed for decent IOps (where 5400rpm is suited for backup arrays) and in this case highest possible density platter is needed.

    Article provides good data for historical references.
  • 0 Hide
    anamaniac , March 3, 2010 10:28 AM
    wuzyArticle provides good data for historical references.

    It does. =)
    Now, how about another comparison when they release a single platter 1TB 7200RPM 3.5" HDD?
    I'm going to stick with my 1TB Samsung and 500GB 7200x10's for now, but Hitachi, you certainly do have me considering you for my next big purchase.