Getting around WRITE_DMA errors

chris at chris at
Sat Jan 14 15:54:59 PST 2006

Try the bios ?
> Sebastian wrote:
>> Markus Trippelsdorf wrote:
>>> Are you sure that your hard drive is not dying? Run smartctl -a
>>> /dev/ad0 and see if any errors were being logged.
>>> (smartctl is part of the smartmontools port)
>>> You should also try another cable.
>> Thanks for the response. I'm reasonably sure, the disk is brand new,
>> and though it could certainly be bad, I installed Linux on the system
>> this morning without issue. I've tried two different UDMA cables also,
>> just to be sure. Under PIO4 mode in BSD (by setting hw.ata.ata_dma=0),
>> I can install and then write data to my heart's content without any
>> errors.
>> I'm currently reinstalling again, because I believe a partition has
>> become corrupted after panicking with the disk in UDMA6 mode.
> Just as a followup: Attempting to run "atacontrol mode ad0 UDMA6"
> resulted in WRITE_DMA48 errors and a panic. Afterwards, disk access was
> slow, and trying to use _any_ UDMA mode resulted in DMA errors being
> logged, and eventually another panic.
> Having briefly tested UDMA3-5 with success previously, I felt that the
> partitions must have been corrupted somehow, so I reinstalled FreeBSD
> from scratch. It's better, after booting with "hw.ata.ata_dma=0" and
> then running "atacontrol mode ad0 UDMA5", it's running fine using UDMA5
> and copying lots of data around:
>   # atacontrol mode ad0
>   current mode = UDMA100
> So my question remains: How do I tell FreeBSD to use UDMA5 on this drive
> at boot-time?
> Thanks.
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