mirror_zfs/cmd/sas_switch_id/sas_switch_id
Ned A. Bass 560bcf9d14 Multipath device manageability improvements
Update udev helper scripts to deal with device-mapper devices created
by multipathd.  These enhancements are targeted at a particular
storage network topology under evaluation at LLNL consisting of two
SAS switches providing redundant connectivity between multiple server
nodes and disk enclosures.

The key to making these systems manageable is to create shortnames for
each disk that conveys its physical location in a drawer.  In a
direct-attached topology we infer a disk's enclosure from the PCI bus
number and HBA port number in the by-path name provided by udev.  In a
switched topology, however, multiple drawers are accessed via a single
HBA port.  We therefore resort to assigning drawer identifiers based
on which switch port a drive's enclosure is connected to.  This
information is available from sysfs.

Add options to zpool_layout to generate an /etc/zfs/zdev.conf using
symbolic links in /dev/disk/by-id of the form
<label>-<UUID>-switch-port:<X>-slot:<Y>.  <label> is a string that
depends on the subsystem that created the link and defaults to
"dm-uuid-mpath" (this prefix is used by multipathd).  <UUID> is a
unique identifier for the disk typically obtained from the scsi_id
program, and <X> and <Y> denote the switch port and disk slot numbers,
respectively.

Add a callout script sas_switch_id for use by multipathd to help
create symlinks of the form described above.  Update zpool_id and the
udev zpool rules file to handle both multipath devices and
conventional drives.
2011-06-23 10:46:06 -07:00

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#!/bin/sh
#
# sas_switch_id
#
# Callout script for multipathd to obtain disk UUIDs. Combine the UUID
# from the scsi_id program with the SAS switch port number and enclosure
# bay number, if available. This naming convention enables easier
# identification of the physical drive location when multiple disk
# enclosures are accessed via a SAS switch. For other storage
# topologies just return the undecorated UUID of the drive.
PHYS_PER_PORT=4
DEV=
usage() {
cat << EOF
Usage: sas_switch_id [-d disk] [-p phys_per_port]
-d Basename of the disk device [default=none]
-p Number of PHYs per switch port [default=${PHYS_PER_PORT}]
-h Show this message
EOF
exit 0
}
while getopts 'd:p:h' OPTION; do
case ${OPTION} in
d)
DEV=${OPTARG}
;;
p)
PHYS_PER_PORT=${OPTARG}
;;
h)
usage
;;
esac
done
if [ -z "$DEV" ] ; then
echo "Error: missing required option -d"
exit 1
fi
UUID=`/lib/udev/scsi_id --whitelisted --device=/dev/$DEV`
if [ $? != 0 -o -z "$UUID" ] ; then
exit 1
fi
sys_path=`udevadm info -q path -p /sys/block/$DEV`
dirs=(`echo "$sys_path" | tr / ' '`)
switch_port_dir="/sys"
# Get path up to /sys/.../hostX
for (( i=0; i<${#dirs[*]}; i++ )); do
d=${dirs[$i]}
switch_port_dir=$switch_port_dir/$d
echo $d | egrep -q -e '^host[0-9]+$' && break
done
if [ $i = ${#dirs[*]} ] ; then
echo $UUID
exit 0
fi
# The directory three levels beneath /sys/.../hostX contains
# symlinks to phy devices that reveal the switch port number.
# Lowest phy number is $PHYS_PER_PORT*switch_port_number.
for (( j=(($i+1)) ; j<(($i+4)); j++ )); do
switch_port_dir=$switch_port_dir/${dirs[$j]}
done
pushd $switch_port_dir > /dev/null
PHY=`ls -d phy* 2>/dev/null | head -1 | awk -F: '{print $NF}'`
PORT=$(( $PHY / $PHYS_PER_PORT ))
popd > /dev/null
if [ -z "$PHY" ] ; then
echo $UUID
exit 0
fi
# Look in /sys/.../sas_device/end_device-X for the bay_identifier
# attribute.
end_device_dir=$switch_port_dir
for (( k=$j ; k<${#dirs[*]} ; k++ )); do
d=${dirs[$k]}
end_device_dir=$end_device_dir/$d
if echo $d | egrep -q -e '^end_device' ; then
end_device_dir=$end_device_dir/sas_device/$d
break
fi
done
SLOT=`cat $end_device_dir/bay_identifier 2>/dev/null`
if [ -z "$SLOT" ] ; then
echo $UUID
exit 0
fi
echo "$UUID-switch-port:$PORT-slot:$SLOT"