#!/bin/bash
BLOCKSIZE=512 # Make sure this is in bytes
CHUNKSIZE=128  # Make sure this is in KiB
NUMSPINDLES=3
RAID_TYPE=5
RAID_DEVICE_NAME="/dev/md0" # Specify device name for your RAID device
FSLABEL="name" # specify filesystem label for generating mkfs line here

case "$RAID_TYPE" in
0)
    RAID_DISKS=${NUMSPINDLES};
    ;;
1)
    RAID_DISKS=${NUMSPINDLES};
    ;;
10)
    RAID_DISKS=${NUMSPINDLES};
    ;;
5)
    RAID_DISKS=`echo "${NUMSPINDLES} - 1" | bc`;
    ;;
6)
    RAID_DISKS=`echo "${NUMSPINDLES} - 2" | bc`;
    ;;
*)
    echo "Please specify RAID_TYPE as one of: 0, 1, 10, 5, or 6."
    exit
    ;;
esac

SUNIT=`echo "${CHUNKSIZE} * 1024 / 512" | bc`
SWIDTH=`echo "$RAID_DISKS * ${SUNIT}" | bc`

echo "System blocksize=${BLOCKSIZE}"
echo "Chunk Size=${CHUNKSIZE} KiB"
echo "NumSpindles=${NUMSPINDLES}"
echo "RAID Type=${RAID_TYPE}"
echo "RAID Disks (usable for data)=${RAID_DISKS}"
echo "Calculated values:"
echo "Stripe Unit=${SUNIT}"
echo -e "Stripe Width=${SWIDTH}\n"
echo "mkfs line:"
echo -e "mkfs.xfs -b size=${BLOCKSIZE} -d sunit=${SUNIT},swidth=${SWIDTH} -L ${FSLABEL} ${RAID_DEVICE_NAME}\n"
echo "mount line:"
echo -e "mount -o remount,sunit=${SUNIT},swidth=${SWIDTH}\n"
echo "Add these options to your /etc/fstab to make permanent:"
echo "sunit=${SUNIT},swidth=${SWIDTH}"