kern/162256: [mpt] QUEUE FULL EVENT and 'mpt_cam_event: 0x0'

[Alexander Haderer]

>Number:         162256
>Category:       kern
>Synopsis:       [mpt] QUEUE FULL EVENT and 'mpt_cam_event: 0x0'
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Wed Nov 02 19:20:07 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Alexander Haderer
>Release:        8.1 R i386
>Organization:
LoeScap Technology GmbH
>Environment:
FreeBSD my.host.here 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul 19 02:55:53 UTC 2010     root at almeida.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
Having SCSI disks connected to an mpt based controller, me and other people experience problems with disappearing disks with messsages "mpt_cam_even: 0x0" like in [1] or QUEUE FULL EVENT like in [2]. Others see failing requests or requests timing out like in PR 117688 [3]. More examples can be found via a search engine.

Often, but not always people are running a software RAID on these drives, gmirror or ZFS based for example. The error messages appear, when there is some load on the disks / raid.

A workaround mentioned on some sites is to reduce the "tags" of the disks connected to mpt using "camcontrol tags -N value"

Probably this behaviour is mpt firmware related and can't be solved by fixing the mpt driver.

My change request:

What about adding a sysctl variable, where one can set the tags value for each mpt conroller connected to the system? Doing so one can automatically set the tags value at boot time.

Mention this sysctl variable in the mpt man page.


[1] http://forums.freebsd.org/showthread.php?t=17802&highlight=mpt0

[2] http://ndok.wordpress.com/2009/07/03/mpt0-queue-full-event-bus-0x00-target-0x08-depth-128/

[3] http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/117688
>How-To-Repeat:
Run a machine with mpt controller, connect daN disks, setup a gmirror / ZFS raid and generate disk load (writes?).
>Fix:
No real fix, but instead a shell script to be put in /usr/local/etc/rc.d. To enable it add to rc.conf:

mpttags_enable="YES"
mpttags_value="100"

to set the tags value for all daN disks attached to all mpt controllers to 100.

Please find this script attached to this PR.

Patch attached with submission follows:

# This is a shell archive.  Save it in a file, remove anything before
# this line, and then unpack it by entering "sh file".  Note, it may
# create directories; files and directories will be owned by you and
# have default permissions.
#
# This archive contains:
#
#	mpttags
#
echo x - mpttags
sed 's/^X//' >mpttags << '5d94cc96def1eaaabbdd9ab978da76db'
X#!/bin/sh
X
X# PROVIDE: mpttags
X# REQUIRE: FILESYSTEMS
X#
X# Set parameter 'tags' to value $mpttags_value for all daN disks connected
X# to an mpt controller using command 'camcontrol tags -N val'
X# 
X# Add the following line(s) to /etc/rc.conf to enable mpttags:
X#
X#  mpttags_enable="YES"
X#
X#  mpttags_value="N"   An integer value for tags, range 2..255, defaults to 100
X#
X# This scripts takes one of the following commands:
X#
X#   start 
X#
X
X. /etc/rc.subr
X
X# set default values
Xname="mpttags"
Xrcvar=`set_rcvar`
Xmpttags_enable=${mpttags_enable:-"NO"}
Xmpttags_value=${mpttags_value:-"100"}
X
Xstart_cmd="mpttags_start"
Xstop_cmd=":"
X
X# set default programs
XCAMCONTROL=${CAMCONTROL:-"/sbin/camcontrol"}
XEGREP=${EGREP:-"/usr/bin/egrep"}
X
Xmpttags_start()
X{
X	for disk in $(${SYSCTL_N} kern.disks); do 
X		case ${disk} in
X
X		da[0-9]|da[0-9][0-9])
X			if ${CAMCONTROL} tags ${disk} | 
X			   ${EGREP} '^\(pass[0-9]{1,2}:mpt[0-9]:' > /dev/null ;
X			then
X				${CAMCONTROL} tags ${disk} -N ${mpttags_value} \
X				> /dev/null
X			fi
X			;;
X		*)
X			;;
X		esac
X	done
X}
X
Xload_rc_config $name
Xrun_rc_command "$1"
5d94cc96def1eaaabbdd9ab978da76db
exit



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