Saturday, August 29, 2009

Comparison of SSD and drum-based HD (HDD)

I am in the process of assembling a PC for my friend. So I was gathering information on various components. I thought I must share what I learned about hard disks.

The latest breed of hard disks in the PC segment are called Solid State Disks (SSD). Though the technology is not new, the price has become affordable in the recent few years. Due to their formidable high prices earlier, computers were usually shipped with the drum-based hard disks (I will refer to them as simply HDD). You can read about SSDs from wikipedia.

These are the points I wanted to share:
1) The transfer speed of SSD is faster compared to HDD. A good 7200 RPM hard disk usually has a transfer rate around 70 MBytes/sec. Where as SSD has a transfer speed around 200 MBytes/sec. Remember I am giving an approximate figure and speeds vary for read and write. One of the recent additions to the hard disks is 10000 RPM hard disks. I found them to be faster than SSD. For e.g. Western Digital's Velociraptor has a peak transfer speed of 384 MBytes/Sec.

2) The life time of SSD is very good. The Mean Time Between Failure for an SSD is in millions of hours. For e.g. OCZ's 60 GB SSD is having an MTBF of 1.5 million hours. So SSDs are more robust.

3) The shock tolerance of the SSD is substantially higher. For e.g. OCZ's 60 GB SSD's max shock resistance is 1500G. But for Velociraptor, the same value is 300G.

4) The SSDs make less noise compared to HDD as there is no mechanical parts.

5) One of the cons of the SSDs is the price per bit of SSD is still substantially higher. For e.g. a OCZ's 60 GB hard disk costs $219, where as the Velociraptor 300 GB costs $229.

Whats my advice? If you are serious about the life of the hard disk, try SSD. If you are crazy about the speed, try Velociraptor.

What have I decided? I have decided to buy the SSD and to add an external hard disk with eSATA interface. I have decided to buy Iomega Prestige 1TB.

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