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Hello,

I'm running OpenBSD 3.6/macppc on a 800mhz iMac, which is a half sphere
with integrated everything, including an integrated flat panel display.

The machine has a hard drive and a DVD-RW drive on the same channel,
master and slave, respectively. Unfortunately I cannot rearrange this
drive configuration so that the drives are each on a different channel,
since there is no way to open the case without destroying it.

Occasionally I get "soft errors" on the hard drive, which causes the IDE
bus to time out. This happens particularly often when I am burning DVDs,
which causes the burn to fail with an I/O error in the middle of the burn
(I suppose because the devices are on the same channel).

So, I disabled Ultra-DMA by using this line in my kernel config file:
wd0 at wdc0 drive 0 flags 0x0fac

This seems to have solved my "soft error" problem, as I have not yet seen
any soft errors on kernels compiled with this flag. However, I can no
longer burn DVDs now. The program I use to burn DVDs is growisofs, part
of the DVD+RW-tools package.... which I believe is the only available
option for burning DVDs under OpenBSD/macppc. When Ultra-DMA is disabled,
it won't even start burning a DVD, it errors out with this message:
/dev/rcd0c: FEATURE 21h is not on, engaging DAO... /dev/rcd0c:
reserving 2126656 blocks
:-[ RESERVE TRACK failed with SK=5h/ASC=72h/ACQ=05h]: Input/output error
/dev/rcd0c: "Current Write Speed" is 1.0x1385KBps.
:-[ WRITE@LBA=0h failed with SK=4h/ASC=08h/ACQ=01h]: Input/output error -(
:attempt to re-run with -dvd-compat -dvd-compat to engage DAO or apply
:full blanking procedure -( write failed: Input/output error

Is it possible to disable Ultra-DMA on wd0, but leave it enabled for cd0?
Even when I specify that only wd0 should have UDMA disabled, OpenBSD
disabled UDMA on both drives. I've even tried explicitly enabling UDMA on
the CD device with lines like this in my kernel configuration:
atapiscsi* at wdc0 channel 0 flags 0x0aac
cd0 at scsibus0 target 0 lun 0 flags 0x0aac

But no matter what I do, if UDMA is disabled on wd0 it is disabled for all
drives. Is there a way to get around this?

thanks,
Jim Faulkner

On Wed, 19 Jan 2005 15:46:37 -0500, Jim Faulkner wrote:

> Occasionally I get "soft errors" on the hard drive, which causes the IDE
> bus to time out. This happens particularly often when I am burning DVDs,
> which causes the burn to fail with an I/O error in the middle of the burn
> (I suppose because the devices are on the same channel).

For the curious, here is the error message I get:
Jan 19 18:32:58 nonplus /bsd: wdc0:0:0: intr with DRQ (st=0x58<DRDY,DSC,DRQ>)
Jan 19 18:32:58 nonplus /bsd: wdc0:0:0: intr with DRQ (st=0x58<DRDY,DSC,DRQ>)
Jan 19 18:32:58 nonplus /bsd: wd0a: device timeout writing fsbn 29843072 of 29843072-29843103 (wd0 bn 29846096; cn 29609 tn 3 sn 35), retrying
Jan 19 18:32:58 nonplus /bsd: wd0a: device timeout writing fsbn 29843072 of 29843072-29843103 (wd0 bn 29846096; cn 29609 tn 3 sn 35), retrying
Jan 19 18:32:58 nonplus /bsd: wd0: soft error (corrected)
Jan 19 18:32:58 nonplus /bsd: wd0: soft error (corrected)

Jim Faulkner <jfaulkne@ccs.neu.edu> writes:

> > Occasionally I get "soft errors" on the hard drive, which causes the IDE

> Jan 19 18:32:58 nonplus /bsd: wd0a: device timeout writing fsbn 29843072 of 29843072-29843103 (wd0 bn 29846096; cn 29609 tn 3 sn 35), retrying
> Jan 19 18:32:58 nonplus /bsd: wd0a: device timeout writing fsbn 29843072 of 29843072-29843103 (wd0 bn 29846096; cn 29609 tn 3 sn 35), retrying
> Jan 19 18:32:58 nonplus /bsd: wd0: soft error (corrected)
> Jan 19 18:32:58 nonplus /bsd: wd0: soft error (corrected)

Ignore the "soft" aspects. fsbn (file system block number) 29843072
is bad. Don't use it. How? See badsect(8). Follow the instructions
there. Then think about about getting a new disk :-)

// marc