Normal Read Speed, Very Slow Write Speed


Compaq with 1GB of RAM (I know its low, but I don't see this as being the source of the problem since the other hdd in the same system reports normal write speeds) running Windows Vista Ultimate. There are two SATA hard drives in the system one which is used as a file share, and the other used for the OS. The poor performing HDD has the OS on it, and is a SATA drive 300 the other drive is 150. I have set the drive to 150 with jumper settings with no change. The system is being optimized for performance, with a focus on background services, but none of those options effect this issue.

The HDD with the OS on it has normal reads, but very slow writes. I know the easy fix is to replace the drive, but I like to get to the bottom of why things happen. If its a perfectly good HDD then replacing it would be superfluous.

Bios reports nothing untoward.

Its not a DMA issue as the drive is performing fines on reads. Only the writes are slow.

My bench marking software reports the following for the drive:

Seq. Reads 46.69 MB/s
Seq. Writes 1.03 MB/s
Rand. Reads 512k 21.61 MB/s
Rand Writes 512k 1.19 MB/s
Rand Reads 64k 17.61 MB/s
Rand Writes 64k 1.26 MB/s

I have replaced the cable and connected to different channels. Nothing seems to effect the write speeds whatsoever.

Any ideas?
6 answers Last reply
More about normal read speed slow write speed
  1. Run some disc diagnostics on it; it is likely failing.
  2. What drive is it? 47MB read is low for any recent drive. My Seagate 7200.10 does around 60MB I think.
  3. PhilFrisbie said:
    Run some disc diagnostics on it; it is likely failing.

    All of the diagnostics check out. WD's diagnostic tool, and the drive via smart all report that the drive is ok.

    There are no bad sectors.

    It's a WD1600AAJS (Western Digital 160 GB 300 SATA)
  4. Strange. What type of virus protection are you running? Disable the virus protection and rerun the speed tests.
  5. Kasperski, but I have already tried that.

    I am going to use one of my personal hard drives (this is a work computer) and clone the drive, then see if it still has problems as a secondary drive in a different system. If so then I will just replace it and chalk it up to faulty manufacturing or something.

    I usually only think of HDD failures as being media related, but I supposed the write head can go bad also.
  6. Just as an update... The hard drive continued to get slower, until it stopped working. Certainly a different kind of HDD failure, but a failure none the less. Perhaps the write head was bad.
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