LUN maniuplation in rhel

Title:

LUN maniuplation in rhel

Author:

Douglas O’Leary <dkoleary@olearycomputers.com>

Description:

Commands/processes to manipulate luns in rhel

Date created:

08/2013

Date updated:

08/2013

Disclaimer:

Standard: Use the information that follows at your own risk. If you screw up a system, don’t blame it on me…

Overview:

These commands are available on the web; but, I’m getting tired of hunting them down - and the ones to deallocate luns aren’t out there, from what I’ve seen:

Allocate new lun (without rebooting):

• Store a copy of the disks before any scans: cp /proc/partitions /tmp/pre

• ID the number of controllers: ll /sys/class/scsi_host

• Execute the scan by putting three ‘-’ separated by spaces into the file called scan under each host#

for i in $(seq 0 #)
do
    echo '- - -' > /sys/class/scsi_host/host${i}/scan
done

• If the disks don’t show up, and this is a new array that you’re adding, execute a storage array scan

for i in $(seq 0 #)
do
    echo 1 > /sys/class/fc_host/host${i}/issue_lip
done

• ID any new disks. If no difference, reboot and check again

cp /proc/partitions /tmp/post
diff /tmp/pre /tmp/post

• Add wwids to blaclist_exceptions section, if appropriate. Check How to ID WWID from lun for details on identifying the wwid

cd /etc; rcsdiff multipath.conf # check it in if differences.
#
for pv in $(diff /tmp/pre /tmp/post | grep sd | awk '{print $NF}')
do
    scsi_id --page=0x83 --whitelisted --device=/dev/${pv}
done| sort -u | while read wwid
do
    print "    wwid \"%s\"\n" ${wwid}
done | tee -a /etc/multipath.conf
vi /etc/multipath.conf # mv newly added wwids to blacklist_exceptions section.
ci -l -m'updated blacklist_exceptions" multipath.conf

Deallocate luns from a system:

• Ensure luns are not in use:

  • VGs

  • Partitions

  • oracleasm

• Get list of disks to remove. You’ll need both lists:

  • If you have a list of sd’s, ID multipath devs via multipath -ll ${sd}

  • If you have a list of multipath devs, ID the sds via multipath -ll ${mpath} | awk '{print $3}'

• Clean up multipath.conf

for pv in $(cat list-o-sds)
do
    scsi_id --page=0x83 --whitelisted --device=/dev/${pv}
done| sort -u | while read wwid
do
    eval "perl -i -nle 'print unless (m{${wwid}})' /etc/multipath.conf"
done

• Flush mulitpath:

  for mp in $(cat list-o-mpaths)
  do
      multipath -f ${mp}
  done
  

• Eject the device:

  for pv in $(cat list-o-sds)
  do
      echo 1 > /sys/bloc/${pv}/device/delete
  done
  

• Possibly reboot if devices aren’t gone from /proc/partitions.