ccd on NATA problem - ata0: FAILURE - oversized DMA transfer attempt 73728 > 65536

[Matthew Dillon]

:Ok, I tried the patched kernel, with a modification to ata-dma.c to
:reduce max DMA size of the second channel to 16k.  ccd devices span
:on these two channels, and one of them is used as /usr/obj and another
:for /home.  I observed no errors during `make -sj3 buildworld'.  I also
: tried to enlarge the stripe size from 1152 to 64k, but newfs barfed
:on it (Invalid argument), so I could only use 65535.
:
:Cheers.

    Excellent.

    64k?  Those numbers are in sectors!  1152 = 576KB. 64K = 32MB stripe
    size.   I'll check over the CCD code to see why the larger stripe
    size didn't work, it should be something simple stupid.  Newfs should
    have had no visibility into the stripe size.

    Could you explain the modification you made to ata-dma.c to
    reduce the max DMA size of the second channel?  Does your second
    channel not work without that?  I'd like to see the patch too.

    I will commit the strategy fix now.

					    -Matt