WARNING: WRITE_DMA UDMA IRCR error

[James R. Van Artsalen]

Markus Schanovsky wrote:

> Mar 26 09:02:25 free kernel: ad4: WARNING - WRITE_DMA UDMA ICRC error 
> (retrying request) LBA=118
> 169055
>
> Now I solved the problem with sysctl hw.ata.ata_dma = 0 in my 
> /boot/loader.conf - there are no write errors further.
> But what's the disadvantage of turning ata_dma off?
> Speed?

I have never seen that error.  What disk controller are you using?  Do 
you get that error with any other disk controller?  Try different sATA 
cables?

Boot into single-user mode and do a manual "fsck /usr" and make sure the 
disk is really OK after make buildworld.

Turning off DMA will slow down disk transfers and increase CPU.  Worse, 
it probably doesn't really fix the problem but rather hides it.