#!/bin/sh
################################################################################
#
# SCRIPT:       load_balance
# VERSION:      2.0
# AUTHOR:       Dave Thompson, NSS, ISD, Lee County Clerk of Courts
# RELEASE DATE: 06/20/2005
#
# DESCRIPTION:  load_balance balances the load across controllers.
#
#  NEW IN THIS RELEASE:
#
# 1.1: a. Changed references from disks to logical volumes, as it more
#         accurately reflects what is being evaluated.
#      b. Corrected an error that referenced the number of physical disks rather
#         than the number of logical volumes.
#      c. Added a feature that writes a notification message to syslog
#         immediately before performing a vgreduce.
# 2.0: a. This is a major re-write of load_balance.  Since most everything has
#         been changed, it's pointless to list all the changes.
#
################################################################################

# Variables.

IFS="
"
export PATH=/usr/bin:/sbin:/usr/sbin:
SCRIPT="load_balance"
VERSION="2.0"
USER=`who am i | awk '{print $1}'`

TMP_DIR="/tmp/sysadmin"
UNIQ_CTLRS="${TMP_DIR}/.${SCRIPT}_uniq_ctlrs.out"
ALL_PV="${TMP_DIR}/.${SCRIPT}_all_pv.out"
ALL_PV_STRIPPED="${TMP_DIR}/.${SCRIPT}_all_pv_stripped.out"
VG_DISKS="${TMP_DIR}/.${SCRIPT}_vg_disks.out"
CTLR_LIST="${TMP_DIR}/.${SCRIPT}_ctlr_list.out"
FILELIST="${TMP_DIR}/.${SCRIPT}_filelist.out"


# Introduce script to the systems administrator.

echo "\n${SCRIPT} ${VERSION}
----------------
${SCRIPT} shows the primary and alternate paths of logical volumes to their
disk devices and allows the paths to be swapped, in order to balance the load
across both controllers.  However, vg00 is excluded, since it should be on the
internal disk drives.

${SCRIPT} can automatically balance the load when the "-auto" flag is used.
In order to give the systems administrator more control, when the "-auto" flag
is not used, ${SCRIPT} presents the current configuration, and it allows the
user to determine which logical volumes should be configured to the alternate
path.

Usage: ${SCRIPT} [-auto]

Press \"return\" to continue...\c\n"
read RETURN


# Set auto-balance if specified.

AUTO="NULL"

if [ "${1}" = "-auto" ]; then
 AUTO="ON"
fi


# Function to clean up temporary files.

cleanup () {
 echo "\nCleaning up temporary files...\n"
 echo "${UNIQ_CTLRS}\n${ALL_PV}\n${ALL_PV_STRIPPED}\n${VG_DISKS}\n${CTLR_LIST}\n${FILELIST}" > ${FILELIST}
 for FILE in `cat ${FILELIST}`; do
  if [ -f "${FILE}" ]; then
   echo "Removing ${FILE}..."
   rm ${FILE}
   echo "Done."
  fi
 done
 echo "\nAll temporary files have been removed.\n"
}


# Set trap to clean up and exit if this script is killed.

kill_do() {
 echo "\nWARNING: ${SCRIPT} was abruptly killed."
 cleanup
 exit 1
}

trap kill_do 1 2 3 15 30


# Function to create a list of the current state of all PV's.

all_pv() {
 if [ -f "${ALL_PV}" ]; then
  rm ${ALL_PV}
 fi
 if [ -f "${ALL_PV_STRIPPED}" ]; then
  rm ${ALL_PV_STRIPPED}
 fi
 for VG_DIR in `ls -d /dev/vg* | grep -v vg00`; do
  echo "#${VG_DIR}" >> ${ALL_PV}
  vgdisplay -v ${VG_DIR} | sed -e '1,/Physical volumes/d' -e '/Physical volume groups/,$d'\
 | grep "PV Name" | awk '{print $3,$4}' >> ${ALL_PV}
 done
 cat ${ALL_PV} | egrep -v "Alt|#" > ${ALL_PV_STRIPPED}
}


# Create a list of all the PV's.

all_pv


# Display controllers.

cat ${ALL_PV} | grep -v "#" | awk '{print $1}' | sed -e 's/\/dev\/dsk\///' -e 's/t[0-9]d[0-9]//'\
 | sort -n | uniq > ${UNIQ_CTLRS}
echo "\nControllers:"
cat ${UNIQ_CTLRS}


# Determine the number of PV's that should be using each controller, and report.

echo "\nPV's that should be using each controller as their primary paths: \c"
PV_FULL_COUNT=`cat ${ALL_PV_STRIPPED} | wc -l`
PV_HALF_COUNT=`expr ${PV_FULL_COUNT} / 2`
echo "${PV_HALF_COUNT}"


# Assign variables to controllers.

N="0"
for CONTROLLER in `cat ${UNIQ_CTLRS}`; do
 N=`expr ${N} + 1`
 if [ "${N}" = "1" ]; then
  CTLR1="${CONTROLLER}" > ${CTLR_LIST}
  elif [ "${N}" = "2" ]; then
  CTLR2="${CONTROLLER}" >> ${CTLR_LIST}
  else
  echo "WARNING:  Only two controllers can be used with ${SCRIPT}.  Exiting..."
  cleanup
  exit 1
 fi
done


# Function to gather stats on both controllers.

view_ctlrs() {
 all_pv
 echo "\nPV's using ${CTLR1} as the primary path:  \c"
 CTLR1_COUNT=`grep ${CTLR1} ${ALL_PV_STRIPPED} | wc -l`
 echo ${CTLR1_COUNT}
 echo "PV's using ${CTLR2} as the primary path:  \c"
 CTLR2_COUNT=`grep ${CTLR2} ${ALL_PV_STRIPPED} | wc -l`
 echo ${CTLR2_COUNT}

 if [ "${CTLR1_COUNT}" -gt "${CTLR2_COUNT}" ]; then

  DOMINANT_CTLR="${CTLR1}"
  SECONDARY_CTLR="${CTLR2}"
  DOMINANT_CTLR_COUNT="${CTLR1_COUNT}"
  SECONDARY_CTLR_COUNT="${CTLR2_COUNT}"

  elif [ "${CTLR2_COUNT}" -gt "${CTLR1_COUNT}" ]; then

  DOMINANT_CTLR="${CTLR2}"
  SECONDARY_CTLR="${CTLR1}"
  DOMINANT_CTLR_COUNT="${CTLR2_COUNT}"
  SECONDARY_CTLR_COUNT="${CTLR1_COUNT}"

  elif [ "${CTLR1_COUNT}" = "${CTLR2_COUNT}" ]; then
  echo "\n*** THE LOAD IS BALANCED ***\n"
  echo "Following is the current configuration:"
  cat ${ALL_PV}
  echo ""
  cleanup
  exit 0
 fi

 DIFF=`expr ${DOMINANT_CTLR_COUNT} - ${SECONDARY_CTLR_COUNT}`
 HALF_DIFF=`expr ${DIFF} / 2`
 echo "Difference between ${DOMINANT_CTLR_COUNT} and ${SECONDARY_CTLR_COUNT}:  ${DIFF}"
 echo "PV'S THAT SHOULD BE MOVED FROM ${DOMINANT_CTLR} TO ${SECONDARY_CTLR}:  *** ${HALF_DIFF} ***"

 if [ "${HALF_DIFF}" = "0" ]; then
  echo "\n*** THE LOAD IS BALANCED ***\n"
  echo "Following is the current configuration:\n"
  cat ${ALL_PV}
  echo ""
  cleanup
  exit 0
 fi
}


# Process PV's.

for VG in `ls -d /dev/vg* | grep -v vg00`; do
 VG_UPPER=`echo ${VG} | tr [a-z] [A-Z]`
 echo "\n=====================================================================================\n"
 view_ctlrs
 echo "\n=====================================================================================\n"
 echo "Processing ${VG_UPPER}...\n"
 VG_SHORT=`echo ${VG} | cut -c6-`
 cat ${ALL_PV} | sed -e '1,/'${VG_SHORT}'/d' -e '/#/,$d' | grep "${DOMINANT_CTLR}" | egrep -v "Alt"\
 | awk '{print $1}' > ${VG_DISKS}
 if [ ! -s "${VG_DISKS}" ]; then
  echo "All disks in ${VG_SHORT} are already pointing to the non-dominant controller.  Skipping..."
  else
  echo "Disks on primary paths in ${VG} that may be moved to alternate paths:"
  cat ${VG_DISKS}
 fi
 for DISK_PATH in `cat ${VG_DISKS}`; do
  view_ctlrs
  if [ "${AUTO}" != "ON" ]; then
   echo "\n${DISK_PATH}:  Move to alternate path [y/n]? \c"
   read MOVE
   else
   MOVE="y"
   if [ "${MOVE}" = "y" ]; then
    logger -p user.info -t ${SCRIPT} "NOTICE (from ${USER}):  Moving ${DISK_PATH} to alternate link..."
    echo "\n${DISK_PATH}:  Removing as a primary path in ${VG}..."
    vgreduce ${VG} ${DISK_PATH}
    if [ "${?}" = "0" ]; then
     vgextend ${VG} ${DISK_PATH}
     if [ "${?}" = "0" ]; then
      echo "${DISK_PATH}:  Successfully moved from the primary to the alternate path."
      else
      echo "FAILURE:  ${DISK_PATH}:  Couldn't add back to ${VG}."
     fi
     else
     echo "FAILURE:  ${DISK_PATH}:  Couldn't remove from ${VG}."
    fi
    echo "${DISK_PATH}:  Adding as an alternate link in ${VG}..."
    else
    echo "\n${DISK_PATH}:  No action requested.  Skipping..."
   fi
  fi
 done
done


# Clean up and exit.

cleanup
exit 0