LVM2 RAID6 to RAID0 conversion example

test_raid.sh

#!/bin/bash

NR_DRIVES=5
DRIVE_SIZE=100M
VGNAME=TestVG
LVNAME=TestLV

fail(){
    echo "ERROR: $1"
    exit 1
}

warn(){
    echo "WARNING: $1"
}

case $1 in
    
    create_dev)
        COMPS=""
        for i in $(seq ${NR_DRIVES}); do
            RAW_IMG="DRV_${i}.raw"
            LOOP_DEV="/dev/loop${i}"
            truncate -s ${DRIVE_SIZE} "${RAW_IMG}" || fail "Can't create image ${RAW_IMG}"
            sudo losetup "${LOOP_DEV}" "${RAW_IMG}" || fail "Can't create loopback ${LOOP_DEV}"
            sudo pvcreate "${LOOP_DEV}" || fail "Failed to create PV on ${LOOP_DEV}"
            echo "Loopback ${LOOP_DEV} active, PV created"
            
            COMPS="${COMPS} ${LOOP_DEV}"
        done
        
        sudo vgcreate "${VGNAME}" $COMPS || fail "Failed to create ${VGNAME} VolumeGroup"
        echo "VolumeGroup ${VGNAME} created"
    ;;
    
    
    make_raid6)
        mkdir -p mnt
        sudo lvcreate --type raid6 -l 50%FREE --name "${LVNAME}" "${VGNAME}" || fail "Failed to build LVM2 RAID6"
        lvs -a -o name,lv_layout,devices "${VGNAME}"
        sudo mkfs.ext4 "/dev/${VGNAME}/${LVNAME}" || fail "Failed to format volume"
        sudo mount "/dev/${VGNAME}/${LVNAME}" mnt || fail "Failed to mount volume"
        sudo cp -v "$0" mnt/testfile || fail "Failed to copy file to volume"
        df mnt
        sudo umount mnt || fail "Failed to umount volume"
    ;;
    
    transform_raid0)
        lvconvert --type raid0 "${VGNAME}/${LVNAME}" || fail "Stage 1 failed"
        lvs -a -o name,lv_layout,devices "${VGNAME}"
        
        echo "Waiting 10s for sync"
        sleep 10
        lvconvert --type raid0 "${VGNAME}/${LVNAME}" || fail "Stage 2 failed"
        lvs -a -o name,lv_layout,devices "${VGNAME}"
        
        echo "Waiting 10s for sync"
        sleep 10
        sudo mount "/dev/${VGNAME}/${LVNAME}" mnt || fail "Failed to mount volume"
        diff -q "$0" mnt/testfile || fail "Copied file differs"
        df mnt
        sudo umount mnt || fail "Failed to umount volume"
    ;;
    
    remove_lv)
        mkdir -p mnt
        sudo lvremove "${VGNAME}/${LVNAME}"
    ;;
    
    
    destroy_dev)
        sudo vgremove "${VGNAME}" || warn "Failed to destroy ${VGNAME} VolumeGroup"
        
        for i in $(seq ${NR_DRIVES}); do
            RAW_IMG="DRV_${i}.raw"
            LOOP_DEV="/dev/loop${i}"
            [ -e "${LOOP_DEV}" ] && (sudo losetup -d "${LOOP_DEV}" || fail "Failed to teardown loopback ${LOOP_DEV}")
            echo "Loopback ${LOOP_DEV} inactive"
            rm "${RAW_IMG}" || fail "Failed to delete image ${RAW_IMG}"
            echo "Image ${RAW_IMG} removed"
        done
    ;;
    
esac