Comment 126 for bug 550559

yemu (yemu) wrote :

after searching forums for the solution to my problem for the last couple of days, I think I may have found what's causing freezes (at least for the SSD drives). I'm still testing it to check for 100% if this is the case, but for now I believe that freezes are caused by the driver using the NCQ to communicate with SSD (which is of course pointless - SSD drives don't need to optimze the order of disk operationsm apparently it causes some errors).

The point is that after disabling NCQ for the SSD the errors stoped occuring (I've not encountered any for about 48h - earlier te freezes happened every couple of hours or even more often).

To disable NCQ I added "libata.force=5:noncq" to default kernel options in /etc/default/grub like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash libata.force=5:noncq"

and updated grub.

I used "5:" because errors i saw occured with ata5 info in dmesg - in original report to this bug it was ata6, as you can see above, but it changed to ata5, probably because I was switching ports on my motherboard.

if anyone experience similar bug, please try this solution and report here.

credits for the solution go to: http://ubuntuforums.org/showpost.php?p=10480137&postcount=8