=======================================================
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
    :doc:`How to ID WWID from lun <linux_id_wwid_de_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.