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I have a DELL PE2950 III 2x 3.0GHz Quad Core 32GB RAM.

The card is a Perc 6i SAS dual channel Raid controller w/256mb of cache and BB. The hard disks are

  • 5 x 146GB 15k 3G SAS dell drives ST3146855SS working independent

testing with hdparm I see the following:

/dev/sdb1:
 Timing cached reads:   3858 MB in  2.00 seconds = 1930.17 MB/sec
 Timing buffered disk reads: 378 MB in  3.01 seconds = 125.39 MB/sec
/dev/sdc1:
 Timing cached reads:   3582 MB in  2.00 seconds = 1792.46 MB/sec
 Timing buffered disk reads: 374 MB in  3.01 seconds = 124.06 MB/sec*

But with a desktop computer with 7.2k seagate baracuda I see:

/dev/sdb1:
 Timing cached reads:   12050 MB in  2.00 seconds = 6028.07 MB/sec
 Timing buffered disk reads: 418 MB in  3.01 seconds = 138.93 MB/sec*

So the question Why do I have so low speed?

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closed as not constructive by mdpc, Dave M, RobM, Ward, Khaled Jan 23 '13 at 7:42

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

    
On the "desktop computer" you don't mention its configuration. Specific information on OS is not provided making analysis problematic. –  mdpc Jan 22 '13 at 21:27
    
Did you clear the internal buffer cache before EACH test? Not doing this can generate misleading values in hdparam. –  mdpc Jan 22 '13 at 21:28
    
Timing cached reads should also be ignored. That's purely benchmarking your system's memory and not the actual drive. –  kormoc Jan 22 '13 at 21:31

1 Answer 1

The sustained read specification for this drive is 125MB/s You're getting 124-125MB/s. So you're right where you should be.

Up to 125-MB/s sustained transfer rate -- Ad

The Barracudas have a higher sustained transfer rate due to their higher areal density but also a slightly higher latency due to their lower spin rate (it takes longer for the data to "come around" to the head).

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