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3.5” Test HDDs: Hitachi Ultrastar 15K450, 15K600

3.5" Vs. 2.5" SAS HDDs: In Storage, Size Matters
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Hitachi Ultrastar 15K450

The Ultrastar 15K450 is no longer Hitachi's most current model, as it was replaced by the Ultrastar 15K600 a few months ago. We decided to include it, though, because the 450GB generation has been deployed in large quantities by all hard drive makers, and it's closest to the 147GB, 15,000 RPM drive we used for data density comparison.

Hitachi offers 300GB and 450GB capacity points and utilizes a SAS 3Gb/s interface along with 16MB of cache memory. The 450GB flagship is based on four platters; only three are required for 300GB. Smaller capacities are not available. Power requirements at idle for the 15K450 are lower than on the 15K600, but slightly higher under load.

The 450GB drive is also the hottest of the three, showing why differences between one product generation and the next can be significant. Let’s move on to the current 600GB drive.

Hitachi Ultrastar 15K600

The Ultrastar 15K600 is Hitachi’s top model, available in 300, 450, and 600GB capacities. Once again, it takes four platters to reach the top capacity, while the other two models come with two and three platters. We utilized the 600GB unit in our tests.

Hitachi quadrupled the cache capacity from 16MB to 64MB, and it ugraded the SAS interface from 3 Gb/s to 6 Gb/s. This doesn’t have a direct impact on performance, as the drive's platter I/O throughput is physically limited to a maximum of 195 MB/s. However, SAS 6Gb/s allows for higher peak performance into and off the cache memory, and it's utilized to connect storage applications to host adapters.

The drive requires a bit more power than the 450GB predecessor when it idles, but it's better under load. Since performance increases quite a bit compared to the Ultrastar 15K450, power efficiency both for I/O performance per watt, as well as throughput per watt, makes impressive steps forward. However, the 2.5” drive still does much better.

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  • 1 Hide
    lloydie_p , 9 May 2010 08:39
    "you can easily imagine that a simple RAID with four 3.5” drives could be replaced by six to ten 2.5” drives".

    With the drives mentioned at max throughput 10 x 2.5(15K) would draw 73 watts versus the 59 watts of the 4 x 3.5(15K 600GB) an considering the 4 x 3.5 would = 2.4TB of space and 10 x 2.5 only 1.4TB; unless no one considers capacity I don't see how 2.5 inch drives make for the best compromises.

  • 0 Hide
    andybird123 , 10 May 2010 23:34
    this article does talk about the trade off on throughput and performance per watt, versus raw capacity, but you are right, it's a trade off - at the same price point you can either go for 1.4TB of very fast storage space, or 2.4TB of fast storage

    if you were mainly interested in storage space you could get 4 x 1TB 7200rpm SAS drives for around the same price
  • 0 Hide
    shanky887614 , 10 August 2010 00:52
    this is not realy a valid test

    2.5inch drives where originally designed for laptops hence the small form factor and low power

    so it makes sence they will lose to speed and capacity of there 3.5 inch cosins
  • 0 Hide
    BulkZerker , 11 August 2010 23:53
    shanky887614this is not realy a valid test2.5inch drives where originally designed for laptops hence the small form factor and low power so it makes sence they will lose to speed and capacity of there 3.5 inch cosins


    Howso? Really the future for mass server storage seems to be migrating to 2.5" so it makes sense to see what the tradeoff is.

    Also, everyone who is reporting the spammers please mark them down as well as reporting them so people know they've been reported.