new hard drive trouble

Jonathan Ellis jonathan at carnageblender.com
Sat Dec 30 22:30:40 MST 2006


On Sat, 30 Dec 2006 22:24:34 -0700, "Shane Hathaway"
<shane at hathawaymix.org> said:
> Brian Beardall wrote:
> > I would get the sata II controller. The advantage of the sata II
> > controller is the addition of NCQ. NCQ is what helps make SCSI drives so
> > appealing and fast. NCQ is not available on most sata I contollers. If
> > you have PCI Express on your motherboard you should be able to get a
> > sata II contoller for about $30. If you only have PCI then you can get
> > one for about $63. Sata II is also backwards compatible with Sata I and
> > so it is a win win situation buying a sata II contoller.
> 
> You may be correct, but here's my experience.  Until a month ago I used
> a SATA I drive and controller; now I'm using a SATA II drive and
> controller.  Differences:
> 
> - According to "hdparm -t", the SATA I drive was limited to 55 MB/s.
> The SATA II drive is limited to 76 MB/s.  Both 7200 RPM.  (The 10K RPM
> drives I've experimented with could transfer 90 MB/s.)
> 
> - Although I have NCQ now, I haven't noticed any differences.  I would
> expect NCQ to more fairly balance I/O requests between processes, but I
> haven't seen any sign of that.  However, I don't know of a quantitative
> measure of this.

NCQ is mostly going to make a difference in
- highly random-access oriented loads
- where you're beating the living hell out of the disk

If either of these isn't what you're looking at then I would expect no
measurable difference.

Also NCQ isn't supported out-of-the-box in vanilla kernels before 2.6.19
IIANM.

-Jonathan
 



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