Mailinglist Archive: opensuse (2348 mails)

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Re: [opensuse] Software IDE RAID versus hardware IDE RAID
  • From: "Greg Freemyer" <greg.freemyer@xxxxxxxxx>
  • Date: Wed, 2 Apr 2008 19:37:18 -0400
  • Message-id: <87f94c370804021637p4c17adacjfe60524fe33d01cd@xxxxxxxxxxxxxx>
On Wed, Apr 2, 2008 at 6:24 PM, Sam Clemens <clemens.sam1@xxxxxxxxx> wrote:
Greg Freemyer wrote:

<snip>

3) Strangely, most drives do tie 300 MB/sec to the Sata-2 functions
set, so if you use the 150 MB/sec throttle jumper to slow down the
drive, you loose the NCQ function.


Why deliberately throttle down a drive?
They're slow enough already.
And the SAS/SATA negotiation standard specifies that the
controller and the disk are supposed to negotiate their
speed.

One of the standard troubleshooting techniques on lkml-ide is to
throttle down the drive. A surprising number of times it fixes the
problem.

And the 300 MB/sec Seagates I've been buying all come with the jumper
installed. (ie. they are throttled when shipped.)

FYI: We buy about 20 to 50 drives a month for our lab depending on
what is going on. First thing we do is wipe them. (dd if=/dev/zero
of=/dev/sdb). We occasionally try wiping with and without the jumper
installed. So far no difference, but we tend to use PCI based
controllers, so the PCI bus could be our real throttle.

Greg
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