Using iscsi with multiple targets
Danny Braniss
danny at cs.huji.ac.il
Mon Jul 14 10:00:25 UTC 2008
> FreeBSD 7.0
>
> I have 2 machines with identical configurations/hardware, let's call them A (master)
> and B (slave). I have installed iscsi-target from ports and have set up 3 targets
> representing the 3 drives I wish to be connected to from A.
>
> The Targets file:
> # extents file start length
> extent0 /dev/da1 0 465GB
> extent1 /dev/da2 0 465GB
> extent2 /dev/da3 0 465GB
>
> # target flags storage netmask
> target0 rw extent0 192.168.0.1/24
> target1 rw extent1 192.168.0.1/24
> target2 rw extent2 192.168.0.1/24
>
> I then start up iscsi_target and all is good.
>
> Now on A I have set up my /etc/iscsi.conf file as follows:
>
> # cat /etc/iscsi.conf
> data1 {
> targetaddress=192.168.0.252
> targetname=iqn.1994-04.org.netbsd.iscsi-target:target0
> initiatorname=iqn.2005-01.il.ac.huji.cs::BSD-2-1.sven.local
> }
> data2 {
> targetaddress=192.168.0.252
> targetname=iqn.1994-04.org.netbsd.iscsi-target:target1
> initiatorname=iqn.2005-01.il.ac.huji.cs::BSD-2-1.sven.local
> }
> data3 {
> targetaddress=192.168.0.252
> targetname=iqn.1994-04.org.netbsd.iscsi-target:target2
> initiatorname=iqn.2005-01.il.ac.huji.cs::BSD-2-1.sven.local
> }
>
> So far so good, now come the issues. First of all, it would appear that with
> iscontrol one can only start one "named" session at a time; for example
> /sbin/iscontrol -n data1
> /sbin/iscontrol -n data2
> /sbin/isconrtol -n data3
>
> I guess that is ok, except that each invocation of iscontrol resets the other
> sessions. Here is the camcontrol and dmesg output from running the above 3 commands.
>
> # camcontrol devlist
> <AMCC 9550SXU-8L DISK 3.08> at scbus0 target 0 lun 0 (pass0,da0)
> <AMCC 9550SXU-8L DISK 3.08> at scbus0 target 1 lun 0 (pass1,da1)
> <AMCC 9550SXU-8L DISK 3.08> at scbus0 target 2 lun 0 (pass2,da2)
> <AMCC 9550SXU-8L DISK 3.08> at scbus0 target 3 lun 0 (pass3,da3)
> <NetBSD NetBSD iSCSI 0> at scbus1 target 0 lun 0 (da5,pass5)
> <NetBSD NetBSD iSCSI 0> at scbus1 target 1 lun 0 (da6,pass6)
> <NetBSD NetBSD iSCSI 0> at scbus1 target 2 lun 0 (da4,pass4)
>
>
> [ /sbin/iscontrol -n data1 ]
> da4 at iscsi0 bus 0 target 0 lun 0
> da4: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
>
> [ /sbin/iscontrol -n data2 ]
> (da4:iscsi0:0:0:0): lost device
> (da4:iscsi0:0:0:0): removing device entry
> da4 at iscsi0 bus 0 target 0 lun 0
> da4: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
> da5 at iscsi0 bus 0 target 1 lun 0
> da5: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
>
> [ /sbin/iscontrol -n data3 ]
> (da4:iscsi0:0:0:0): lost device
> (da4:iscsi0:0:0:0): removing device entry
> (da5:iscsi0:0:1:0): lost device
> (da5:iscsi0:0:1:0): removing device entry
> da4 at iscsi0 bus 0 target 2 lun 0
> da4: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
> da5 at iscsi0 bus 0 target 0 lun 0
> da5: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
> da6 at iscsi0 bus 0 target 1 lun 0
> da6: <NetBSD NetBSD iSCSI 0> Fixed Direct Access SCSI-3 device
>
>
> It would appear that rather than appending the new device to the end of the "da"
> devices, it starts to do some type of naming queue after the second device. If I am
> to use these devices in any type of automated setup, how can make sure that after
> these commands, "da6" will always be target 1 (i.e. /dev/da2 on the slave machine).
>
> Next, there is no "startup" script for iscontrol - would that simply have to be
> added the system or is there a way with sysctl that it could be done. The plan here
> is use gmirror such that /dev/da1 on A is mirrored with the /dev/da1 on B using iscsi.
Hi Sven,
I just tried it here, and it seems that at the end all is ok :-)
I think the lost/removing/found has something to do to iscontrol calling
camcontrol rescan - I will check this later, but the end result is that
you should have all /dev/da's.
I don't see any reasonable safe way to tie a scsi# (/dev/dan),
except to label (see glabel) the disk.
The startup script is, at the moment, not trivial, but I'm attaching
it, so someone can suggest improvements :-)
#!/bin/sh
# PROVIDE: iscsi
# REQUIRE: NETWORKING
# BEFORE: DAEMON
# KEYWORD: nojail shutdown
#
# Add the following lines to /etc/rc.conf to enable iscsi:
#
# iscsi_enable="YES"
# iscsi_fstab="/etc/fstab.iscsi"
. /etc/rc.subr
. /cs/share/etc/rc.subr
name=iscsi
rcvar=`set_rcvar`
command=/sbin/iscontrol
iscsi_enable=${iscsi_enable:-"NO"}
iscsi_fstab=${iscsi_fstab:-"/etc/fstab.iscsi"}
iscsi_exports=${iscsi_exports:-"/etc/exports.iscsi"}
iscsi_debug=${iscsi_debug:-0}
start_cmd="iscsi_start"
faststop_cmp="iscsi_stop"
stop_cmd="iscsi_stop"
start_precmd="iscontrol_precmd"
iscontrol_prog=${iscontrol_prog:-"iscontrol"}
iscontrol_log=${iscontrol_log:-"/var/log/$iscontrol_prog"}
iscontrol_syslog=${iscontrol_syslog:-"644 3 100 * JC"}
iscontrol_precmd()
{
setup_syslog "$iscontrol_prog" "$iscontrol_log" "$iscontrol_syslog"
}
iscsi_wait()
{
dev=$1
trap "echo 'wait loop cancelled'; exit 1" 2
count=0
while true; do
if [ -c $dev ]; then
break;
fi
if [ $count -eq 0 ]; then
echo -n Waiting for ${dev}': '
fi
count=$((${count} + 1))
if [ $count -eq 6 ]; then
echo " Failed for dev=$dev"
return 0
break
fi
echo -n '.'
sleep 5;
done
echo "$dev ok."
return 1
}
iscsi_start()
{
#
# load needed modules
for m in iscsi_initiator geom_label; do
kldstat -qm $m || kldload $m
done
sysctl debug.iscsi_initiator=$iscsi_debug
#
# start iscontrol for each target
if [ -n "${iscsi_targets}" ]; then
for target in ${iscsi_targets}; do
${command} ${rc_flags} -n ${target}
done
fi
if [ -f "${iscsi_fstab}" ]; then
while read spec file type opt t1 t2
do
case ${spec} in
\#*|'')
;;
*)
if iscsi_wait ${spec}; then
break;
fi
echo type=$type spec=$spec file=$file
fsck -p ${spec} && mkdir -p ${file} && mount ${spec} ${file}
chmod 755 ${file}
;;
esac
done < ${iscsi_fstab}
fi
if [ -f "${iscsi_exports}" ]; then
cat ${iscsi_exports} >> /etc/exports
#/etc/rc.d/mountd reload
kill -1 `cat /var/run/mountd.pid`
fi
}
iscsi_stop()
{
echo 'iscsi stopping'
while read spec file type opt t1 t2
do
case ${spec} in
\#*|'')
;;
*)
echo iscsi: umount $spec
umount -fv $spec
;;
esac
done < ${iscsi_fstab}
}
load_rc_config $name
run_rc_command "$1"
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