Hard drive access speed
I have a 200gb hard drive that's supposed to transfer at 100 mb/s but it's only getting around 50mb/s. I can't figure out what's wrong with it, unless it's just a normal thing for it not to get close to its 'maximum' speed. It's running udma5, it shouldnt be a cpu problem (2.0 ghz athlon), im using a 80 wire IDE cable, and it's set as Master. It has a shuttle AK38N motherboard ("IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)") that supports transfer speed at 133 mb/s. Here's some info from hdparm.
$ hdparm -tT /dev/hdc Quote:
Quote:
Quote:
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Is dma enabled? What do you get from:
hdparm /dev/hdc |
Hi,
Your hard drive is performing very well. You should be very pleased with the results that you received from hdparm -tT. The 100Mb/S speed that the drive supports is the "interface" speed. That is the integrated drive electronics maximum theorectical transfer speed. The electromechanical part of the drive (the HDA or Head Disk Assembly) cannot transfer data at this speed and will never reach the theoretical maximum. SCSI interfaces can operate at much faster data rates than the highest IDE speed of 133Mb/S but even they're (better engineered-usually) HDA's can't supply data quickly enough. In a SCSI system it takes many HDA's operating through one fast interface to reach the maximum data throughput. IDE interfaces can only access one HDA at any given time so it is impossible for the maximum data transfer speed to be reached. SATA may offer some hope for more SCSI like performance in the future as the standard matures but until then, SCSI rules for high speed data transfer. Faster (IDE) interface speeds allow commands and such to be organised more quickly while allowing the HDA to continue transfering data as efficiently as possible. Other than that there isn't much advantage. As an example. If you obtain two identical HDA's and connect one to a 100Mb/S interface and the other to a 133Mb/S interface and then bench test, you will find that they perform almost identically. The disks won't spin any faster, nor will the heads move or settle quicker, only the electroniics is operating at a higher speed. Hope this helps. .....RainyDay |
100MB/sec is the maximum in theory... you will never reach that.
You drive is a bit slow (I score 52MB/sec with a 80GB on a 3 years old computer) but this is probably mostly due to your motherboard, not your drive fault, atmo. |
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