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I have been working on SSD (solid state disk) for several months..Problems and Questions hit my head unexpectedly..Coz i am a virgin in ssd...
Especially these days I was testing the write-read speed of ssd, which I was always caring....
however result turned out not good as I expected, or even worse Three kinds of read-write were implemented in my test

  1. read and write directly from and into ssd, with openning ssd as a whole device. in windows: _open("\\:g", ***)..
    It can be very tricky and hairy that you'd write a data with size of folds of 512, at the disk position of folds of 512bytes...
    So, If you wanto write just a byte or 4 bytes, you'v to write at least a whole sector one time.
  2. Read and write data from and into files located in SSD...
  3. Read and Write data from and into files in mechanical Disk

I compared the pratices below...I found ssd sucks...the ssd performs worse than mechanical disk... so i am wondering where i can get the potential performance of ssd, since ssd is said to a substitute for mechanical disk in the future.. Nevertheless, I test ssd with a pro-hard-disk tools..ssd is like twice speedier than mechanical disk.

So, why?

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migrated from stackoverflow.com Mar 22 '10 at 2:37

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this belong in superuser.com? –  Jay Atkinson Mar 22 '10 at 2:34
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2 Answers 2

What your tests miss is one area SSDs shine: Effectively no seek or latency times. They aren't really that much better in transfers (and under some conditions are slower), it's that there's no wait for the mechanical device to be in the right position.

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Slight nitpick, 100 microseconds is not zero latency... granted its much faster than the 4-8 milliseconds of a typical hard drive. Also the workload in question (read/write mix, random vs sequential I/O, number of I/Os in the queue) has a dramatic impact on an SSDs latency. Latency is definitely key for SSDs –  Sam Post Mar 22 '10 at 3:36
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Your question could use a bit of cleanup. If you're wondering why a particular SSD performs only twice as fast as a particular Mechanical HD on your computer there are many factors that affect performance.

The throughput of the connection means, the throughput of the drives you're using, the OS, controller card, drivers, firmware, and a thousand other factors contribute to the overall score.

If you provide some details about the particular hardware used in your testings we might be able to give you a better answer.

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