On 01/22/2011 12:31 AM, Dale wrote:
Alan McKinnon wrote:
My notebook works like that too.
Hard disk works fine when everything is set to AHCI, but then the
system won't
boot from CD. So I enabled the IDE driver and the IDE driver for CD-ROMs.
My take on this is that Dell had a vast stock of cheap-skate CD-ROM
hardware
and used them up. The engineering logic would have been "it doesn't
matter
that we use the slow interface for that device, it's still faster than
we can
get the data off the media."
And I thought there was something weird with me on this one. o_O I did
switch it back to AHCI after I got done booting the CD thingy. I really
can't tell any difference in speed between the two and neither could
hdparm -tT either.
hdparm measures raw throughput when reading continuously from one
position to another. AHCI improves performance when the disk needs to
read from several different places, which is the case in every day use.
It does this by providing a feature similar to what SCSI provides:
native command queuing (NCQ). You can read about what this is and why
we want it here:
http://en.wikipedia.org/wiki/Native_Command_Queuing
