Bad disk or kernel (ATA Driver) problem?

[Karl Denninger]

Hi folks;

New one...

I've got a 2 x SATA system here I'm playing with in preparation to move 
over production to 5.x.

These drives have been working under 4.x for quite some time - they're 250GB
Maxtor disks....

ad4: 239372MB <Maxtor 6B250S0/BANC1980> [486344/16/63] at ata2-master SATA150
ad6: 239372MB <Maxtor 6B250S0/BANC1980> [486344/16/63] at ata3-master SATA150

The first disk runs nice and happy.

The second does too, provided that the load isn't too high.  If it is, then I
start to get DMA transfer errors, such as the following:

ad6: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE>
LBA=543191
GEOM_MIRROR: Request failed (error=5). ad6[READ(offset=278048256,
length=102400)]
GEOM_MIRROR: Device m0: provider ad6 disconnected.
ad6: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE>
LBA=300463
ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=90863
ad6: FAILURE - READ_DMA timed out
ad6: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE>
ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=120663
ad6: FAILURE - READ_DMA timed out

I'm having a lot of trouble believing this is an actual disk problem.  Among
other things, its happening at different places - not always at the same
block.

The above (after the first one) are all being provoked with a 
"dd if=/dev/ad6s1 of=/dev/null bs=100k".

Anyone else seeing this with a -STABLE build from the last few days, and
only on a secondary (and/or SATA) channel?

Note that this disk can be reintegrated into the mirror, and it will rebuild
happily.  Its only when I put a real working load on it that things act up.

--
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