Re: ahci.ko in RELENG_8_2, what about atacontrol cap?

On Sun, Apr 03, 2011 at 12:21:55PM +0200, Patrick M. Hausen wrote:
Hello,

Am 02.04.2011 um 11:40 schrieb Jeremy Chadwick:
You want "camcontrol identify adaX". DO NOT confuse this with
"camcontrol inquiry adaX" (this won't work).

identify = for ATA
inquiry = for SCSI

Works perfectly, but I just noticed one really odd thing:

1. boot without ahci.ko:

nas-pmh# atacontrol cap ad4
...
write cache yes yes


2. boot with ahci.ko:

nas-pmh# camcontrol identify ada0
...
write cache yes no


Well? ;-) The system is a HP NL36 - I just found a couple
of articles mentioning that the default setting in the BIOS
setup was write cache disabled. I can check that in the
next couple of days when I take the machine back to the
lab (no monitor/keyboard at my home office).

I'd prefer a way to make sure write cache is enabled via
some tuning from FreeBSD. The disks are dedicated to
a raidz2, so from what I found around the net, write cache
should not pose a major problem. Of course, one will lose
_some_ data at a power outage - what I want to avoid
for home office use is a completely lost file system.
Losing the last time machine backup of my Mac is tolerable.

I don't have an explanation for what you're seeing. I can't reproduce
it on any of our Supermicro systems (ICH9R-based, backed by a multitude
of disk types; Intel X25-M and X25-V SSDs, WD Caviar Black 750GB, 1TB,
and 2TB, etc.).

CC'ing mav@ who might have some ideas. I don't see anything in RELENG_8
that looks relevant (just went through src/sys/dev/ahci's commit log).

Alexander, disk type is here (Seagate ST32000542AS):
http://lists.freebsd.org/pipermail/freebsd-stable/2011-April/062142.html

--
| Jeremy Chadwick jdc@xxxxxxxxxxxx |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP 4BD6C0CB |

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