7.1-RELEASE I/O hang

[Matt Burke]

I have a machine with a PERC6/e controller. Attached to that are 3 disk
shelves, each configured as individual 14-disk RAID10 arrays (the PERC
annoyingly only lets you use 8 spans per array)

I can run bonnie++ on the arrays individually with no problem.
I can also run it across a gstripe of the arrays with no problem.

However running it over the 3 arrays in parallel causes something I/O
related in the kernel to hang.

To define 'hang' better:

It appears anything which needs disk io, even on a different controller
(albeit the same mfi driver), will hang. A command like 'ps' cached in
ram will work but bash hangs after execution, presumably while trying to
write ~/.bash_history

'sysctl -a' works but trying to run 'sysctl kern.msgbuf' also hangs

I've done some research and it seems the usual cause of bonnie++
crashing a system is due to overflowing TCQ. camcontrol doesn't see any
disks, so I've tried setting hw.mfi.max_cmds=32 in /boot/loader.conf but
it hadn't made any difference.

The bonnie++ invocation is this:

(newfs devices mfid[2-3], mount)
bonnie++ -s 64g -u root -p3
bonnie++ -d /data/2 -s 64g -u root -y s >b2 2>&1 &
bonnie++ -d /data/3 -s 64g -u root -y s >b3 2>&1 &
bonnie++ -d /data/4 -s 64g -u root -y s >b4 2>&1 &

and it always hangs on "Rewriting...". It's a fresh 7.1-RELEASE with
nothing else running (devd, sshd, syslogd, etc)


Any ideas?


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