panic: softdep_deallocate_dependencies: unrecovered I/O error

[Joseph Olatt]

On an old Thinkpad T42 running the following:

  FreeBSD peanuts 10.0-RELEASE-p9 FreeBSD 10.0-RELEASE-p9 #0: Mon Sep 15 14:32:29 UTC 2014 root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  i386

it kept crashing while trying to populate the ports tree (svnlite
checkout https://svn0.../ports/head /usr/ports). The panic message was:

  panic: softdep_deallocate_dependencies: unrecovered I/O error

The core.txt.* file is at:

  http://www.eskimo.com/~joji/core.txt.2


Searching the archives led me to bump the value of
kern.bio_transient_maxcnt from 177 -> 1416 (a random value; 177 * 8).
That stopped the crashes and I was able to run the entire ports tree 
population with a hitch.


I'm wondering if there are other folks who have experienced the same 
problem and if the default value of kern.bio_transient_maxcnt in the 
10.x release should be higher than the 177 I had.