#!/bin/bash

#author by John Sun #=======================================================================================================================+ #What is the significance of the file system block size?                                                                | #If my fs block size is set at say 8K does that mean that all read/write I/O will happen at size 8K?                    | #So if my application wants to read say 16 bytes at offset 4097 then a 4K block starting from offset 4096 will be read? | BLOCKSIZE=4096 # Make sure this is in bytes                                                                             | #=======================================================================================================================+ #=======================================================================================================================+ #if you want big I/O requests, you should opt for smaller RAID chunk sizes, and if I/O will be small,                   |        #you should go for larger chunks.                                                                                       | CHUNKSIZE=256  # Make sure this is in KiB                                                                               | #=======================================================================================================================+ NUMSPINDLES=24 RAID_TYPE=6    RAID_DEVICE_NAME="/dev/md-2" # Specify device name for your RAID device #FSLABEL="source" # 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} - 3" | 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} ${RAID_DEVICE_NAME}\n" echo "mount line:" echo -e "mount -o remount,sunit=${SUNIT},swidth=${SWIDTH}\n" echo "Add these options to your /etc/fstab to make permanent:" echo "sunit=${SUNIT},swidth=${SWIDTH}"