Script to optimize the size of an LVM (doing "magic" if reducing) #lvm #reduce #resize

lvm_reduce.sh

#!/bin/bash
if [ -z "$1" ] || [ -z "$2" ] || [ ! -b "$1" ]; then
    echo "Missing a block device, and a size (in that order)";
    echo "   example: $0 /dev/data/apps 3"
    echo "   Ensure your size is bigger than the filesystem"
    echo "   Or type 'optimal' To calculate the size"
    echo
    echo "Size should be in Gigabytes"
    exit 1;
fi
if [ "$(whoami)" != 'root' ]; then
    echo "run this as root"
    exit 1
fi

size="$2"
if [[ "$size" = *"G" ]]; then
    size="${size::-1}"
elif [ "$size" == "optimal" ]; then
    # pass
    :
elif ! [[ $size =~ ^[0-9]+$ ]]; then
    echo "Size: $size is not an integer" >&2
    exit 1
fi

blockdev="$1";

mount "$blockdev" 2> /dev/null
current="$(echo "$(df "$blockdev" --output=size | sed 1d)/(1024*1024) + 1" | bc)"
if [ "$2" == "optimal" ]; then
    size="$(echo "($(df "$blockdev" --output=used | sed 1d) * 1.33333)/(1024*1024) + 1" | bc)"
fi

df -h "$blockdev"
echo -n "Resizing to ${size}G [N/y] "
read -N 1 REPLY
echo
if test "$REPLY" = "y" -o "$REPLY" = "Y"; then
    echo "current: $current"
    if [ "$current" -eq 0 ] || [ "$current" -gt "$size" ]; then
        # shrinking
        umount "$blockdev" || exit 1
        while mount | grep "$blockdev" > /dev/null; do
            umount "$blockdev"
            sleep 2; echo "Trying again"
        done
        e2fsck -f "$blockdev" && \
            resize2fs -p -M "$blockdev" && \
            lvresize -f -L "${size}G" "$blockdev" && \
            resize2fs -p "$blockdev" && \
            mount "$blockdev"
    else
        # expanding
        sudo lvresize -L "${size}G" "$blockdev" && sudo resize2fs -p "$blockdev"
    fi
else
    echo "Cancelled by user"
fi