Script to check and optionally set LBA size to 4k on Western Digital drives.

check-4k-sectors.sh

#!/bin/bash

# Author: griznog
# Purpose: Set any 512b sector drives to 4k sectors.
#
# Notes:
#  * Targets all drives using multipath. 

# Exit on error convenience function.
function die(){
  echo $*
  exit 1
}

# Check current LBA:
function lba_is_4k () {
  local device=/dev/$1
  local retval=0

  [[ -e ${device} ]] || die "${device} not found."

  LBA=$(smartctl -a ${device} | awk '/Logical block size:/ {print $4}')
  if [[ ${LBA} -eq 4096 ]]; then
    retval=0
  elif [[ ${LBA} -eq 512 ]]; then
    retval=1
  else
    die "smartctl -a ${device} | awk '/Logical block size:/ {print \$4}' failed to find LBA size."
  fi

  return ${retval}
}

function lba_set_4k () {
  local device=/dev/$1
  local retval=0
 
  # Abort script if ${device} not found. Seems harsh, but probably indicates
  # the controller has lost it's mind and device names *may* be changing while
  # this script is running.
  [[ -e ${device} ]] || die "${device} not found."
 
  # Change the disk format.
  echo "Setting ${device} to 4k sector LBA."
  sg_format ${device} --format --ffmt=1 --size=4096 --count=-1 --wait --quick
  retval=$?
  if [[ ${retval} -ne 0 ]]; then
    die "ERROR: Setting ${device} to 4k sectors failed."
  else
    echo "Sleeping 5s after setting LBA to prevent bus resets."
    sleep 5s
  fi
  return ${retval}
}

# Check for command line argument.
expected=$1
if [[ -z "${expected}" ]] || [[ "${expected}" -lt 0 ]] || [[ ${expected} -gt 1024 ]]; then
  die "Need 1 argument for number of drives to expect."
fi

# Collect a list of drives, use the first reported path.
# Collect devices from each enclosure. 
devices=( $(sas_devices -v | awk '/35000/ {print $1 "," $4 "," $5 "," $10}') )

# Verify drive count matches expected.
[[ ${#devices[*]} -eq ${expected} ]] || die "Expected ${expected} devices, found ${#devices[*]}"

# Check the drives and display the serial number of 512b sector devices.
# We do this by serial because checking these in bulk may trigger drive/controller resets
# which will cause multipath falures and result in the device name changing. YMMV.
if ! [[ ${PLEASE_DESTROY_MY_DRIVES} == "YES" ]]; then
  echo "# Checking LBA format only."
  echo "# Set PLEASE_DESTROY_MY_DRIVES=YES to immediately convert to 4k sectors."
  echo "# You can also pipe the output of this script to BASH."
  echo "$ Please also verify that for your drives "--ffmt=1" is the right thing to do."
  echo "# You can also see Western Digital to get the HUGO utility and use it to set LBA size."
fi

# Let's probe some drives. No alien abduction needed.
for device in ${devices[*]}; do
  record=( ${device//,/ } )
  bay=${record[0]}
  wwn=${record[1]}
  dev1=${record[2]}
  dev2=${record[3]}
  sn=${record[4]}

  if ! lba_is_4k ${dev1}; then
    if [[ ${PLEASE_DESTROY_MY_DRIVES} == "YES" ]]; then
      lba_set_4k ${dev1} 
    else
      # Show serial number of discovered 512b sector device in case we need to track down a failure later.
      echo "# Drive: ${sn}"
      echo "sg_format /dev/${dev1} --format --ffmt=1 --size=4096 --count=-1 --wait --quick && sleep 5s"
      echo
    fi
  fi
done