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Nikos Chantziaras wrote: |
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> On 01/22/2011 12:31 AM, Dale wrote: |
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>> Alan McKinnon wrote: |
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>>> My notebook works like that too. |
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>>> |
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>>> Hard disk works fine when everything is set to AHCI, but then the |
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>>> system won't |
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>>> boot from CD. So I enabled the IDE driver and the IDE driver for |
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>>> CD-ROMs. |
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>>> |
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>>> My take on this is that Dell had a vast stock of cheap-skate CD-ROM |
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>>> hardware |
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>>> and used them up. The engineering logic would have been "it doesn't |
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>>> matter |
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>>> that we use the slow interface for that device, it's still faster than |
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>>> we can |
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>>> get the data off the media." |
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>>> |
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>> |
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>> And I thought there was something weird with me on this one. o_O I did |
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>> switch it back to AHCI after I got done booting the CD thingy. I really |
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>> can't tell any difference in speed between the two and neither could |
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>> hdparm -tT either. |
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> |
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> hdparm measures raw throughput when reading continuously from one |
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> position to another. AHCI improves performance when the disk needs to |
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> read from several different places, which is the case in every day |
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> use. It does this by providing a feature similar to what SCSI |
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> provides: native command queuing (NCQ). You can read about what this |
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> is and why we want it here: |
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> |
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> http://en.wikipedia.org/wiki/Native_Command_Queuing |
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> |
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|
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Other than copying a file and using time to measure how long it takes, |
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what is the best test of a hard drive's speed? |
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Also, does or can the kernel override the BIOS setting? I think it uses |
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AHCI no matter what is in the BIOS. It seems it would be at least some |
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difference in speed. |
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Nice link. The picture explained it best. I'm sort of simple. lol |
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Dale |
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:-) :-) |
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