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SAS Hard Drives: 15,000 vs. 10,000 RPM

SAS Hard Drives: 15,000 vs. 10,000 RPM
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A speed of 7,200 RPM has been the standard rotation speed for desktop hard drives, as this speed delivers a reasonable combination of reliability, acceptable noise levels, cost and performance. In the laptop space, 2.5" drive speeds usually range from 4,200 RPM to 5,400 RPM but are being increased to 7,200 RPM as we speak, since performance is very important in the 2.5" space. Transfer rates of 2.5" notebook hard drives are usually slower.

The situation is different in the server space, where hard drive speeds are usually at least 10,000 RPM, while some high-end server hard drives have speeds of 15,000 RPM. So what's the real benefit of super-fast drives Compare Prices on SAS 15,000 RPM Drives?

Besides the recording technology, drive rotation speed is the most important factor for a drive's throughput. Most people associate fast rotation speed with high data transfer rates, because this is the most obvious advantage of fast spindle speeds. Whether you boot Windows or copy files that are hundreds of megabytes or even gigabytes in size, quick transfer rates shorten the time it takes for completion of these tasks. Combining high rotation speeds with top-notch recording technologies such as PMR (perpendicular magnetic recording) has repeatedly managed to establish new speed records.

But other performance factors benefit from high rotation speeds, such as seek time. At this point, it is important to differentiate between seek time and access time, because only the latter is really relevant for everyday applications. The access time is the combined latency of the seek time and rotational latency, which applies when the heads have been positioned above the required track, while the required sectors still have to pass by the heads. Faster spindle speeds, hence, always result in decreased rotational latency and decreased average access time.

Unfortunately, 15,000 RPM (or 15k hard drives) are typically more expensive than their slower brothers. Also, large storage capacities aren't available in the high-speed segment. So, you end up spending a lot of money on 15k drives and you might have to live with decreased capacities. We compared Seagate's Savvio 10k.2 and the Savvio 15k.1 while running the drives separately and in four-disk array configurations in RAID 0 and RAID 5.

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    DeanRS , September 18, 2008 3:48 AM
    The Raid 0 benchmarks include Raid 5 File server that is also shown again in the Raid 5 Benchmarks section. Raid 5 shows webserver data and Raid 0 does not. I think that the Raid 0 webserver data is not shown as Raid 5 fileserver data is in its place.