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Articles - Live backup of KVM VM images under RHEL8/9Publication date: 11/16/22 I've created the following script to back up VMs running on top of KVM under RHEL9. I believe it's also compatible with RHEL8, but not tested. It utilizes the recently introduced "backup-begin" function and requires libvirt 7.2+ and QEMU 4.2+. The main advantage (compared to the old method with snapshots) is that it doesn't pause the existing VMs. Besides, I've read about cases when snapshots caused VM image corruption, so certainly preferred to stay away from it. Documentation #!/bin/bash # Doc: https://libvirt.org/kbase/live_full_disk_backup.html # Partially based on https://nixlab.org/blog/backup-kvm-virtual-machines ################ ### SETTINGS ### ################ # Backup dir BACKUP_DIR="/data/_backup" # Retention policy RETENTION=3 # how many copies of each config/image to keep locally # Timestamp TIMESTAMP="$(date +%Y%m%d%H%M%S)" # target vm list (running) VM_LIST=$(virsh list | grep running | awk '{print $2}' | tr 'n' ' ') # Log file LOGFILE="/var/log/kvmbackup.log" STDOUT=1 # 0 - standard output disabled, 1 - enabled, 2 - debug level (TBD) LOG=1 # 0 - logging disabled, 1 - enabled, 2 - debug level (TBD) ################# ### FUNCTIONS ### ################# function print_log { local RET=$? # have to keep previous error code and return it local MSG="$1" local LSTDOUT="${2:-$STDOUT}" # Allow stdout and logging override when calling this function local LLOG="${3:-$LOG}" local CUR_TS="$(date '+%Y%m%d %H:%I:%S')" [ ${LSTDOUT} -ne 0 ] && echo -e "${CUR_TS} - ${MSG}" [ ${LLOG} -ne 0 ] && echo -e "${CUR_TS} - ${MSG}" >> ${LOGFILE} return ${RET} } function die { print_log "ERROR: $1" 1 1 exit } function create_folders { while [ -n "$1" ]; do if [ ! -d "$1" ]; then mkdir -p "$1" && print_log "Folder "$1" was successfully created" || die "Cannot create $1 folder" fi shift done } function purge_expired { local LDIR="$1" local LNAMEREGEX="$2" local LRET="$3" local FILES2DEL="$(ls -1t ${LDIR}/${LNAMEREGEX} | tail -n +$((LRET+1)))" local f if [ -n "${FILES2DEL}" ]; then for f in ${FILES2DEL}; do if [ -f "${f}" ]; then rm -f "${f}" && print_log "Expired file ${f} was purged" || die "Can't purge expired ${f} file" fi done fi } ################# ### MAIN CODE ### ################# [ $(rpm -q libvirt | egrep -c 'libvirt-(7.[2-9]|8|9)') -eq 0 ] && die "Sorry, this script requires libvirt 7.2+" [ $(rpm -q qemu-kvm | egrep -c 'qemu-kvm-(4.[2-9]|[5-9])') -eq 0 ] && die "Sorry, this script requires QEMU 4.2+" print_log "=== START BACKUP OF THE HOST: $(hostname) ===" print_log "Running VMs to be backed up: ${VM_LIST}" for VM in ${VM_LIST}; do print_log "Start backup of VM: ${VM}" BACKUP_CFG="${BACKUP_DIR}/${VM}/config" BACKUP_IMG="${BACKUP_DIR}/${VM}/images" create_folders ${BACKUP_CFG} ${BACKUP_IMG} # Create backup folders if don't exist # Dump VM configuration to XML file OUTXML="${BACKUP_CFG}/${VM}.xml.${TIMESTAMP}" virsh dumpxml "${VM}" > "${OUTXML}" && print_log "Dumped XML config for "${VM}" VM to ${OUTXML} file" || die "Failed to dump XML config for "${VM}" VM to ${OUTXML} file" purge_expired "${BACKUP_CFG}" "${VM}.xml.*" "${RETENTION}" # Start VM image backups and wait for their completion virsh backup-begin "${VM}" >/dev/null 2>&1 && print_log "Backup job for the "${VM}" VM has been started" || die "Failed to start backup job for "${VM}" VM" while [ "$(virsh domjobinfo "${VM}" | grep '^Job type:' | awk '{ print $3 }')" != "None" ]; do sleep 5; done print_log "Backup job for the "${VM}" VM has finished" # Move backup images to the backup subfolder VM_IMAGES=$(virsh domblklist "${VM}" | egrep '[vs]d[a-z].*/' | awk '{print $2}') if [ -n "${VM_IMAGES}" ]; then for VM_IMG in ${VM_IMAGES}; do BKP_LIST=$(ls -1 ${VM_IMG}.* 2>/dev/null) if [ -n "${BKP_LIST}" ]; then for BKP_IMG in $(ls -1 ${VM_IMG}.* 2>/dev/null); do print_log "Found backup image ${BKP_IMG}" BKP_IMG_TS="${BKP_IMG}.${TIMESTAMP}" # Add human-readable timestamp to the image name and then move it to backup folder mv -f "${BKP_IMG}" "${BKP_IMG_TS}" || die "Failed to rename "${BKP_IMG}" image to "${BKP_IMG_TS}"" mv -f "${BKP_IMG_TS}" "${BACKUP_IMG}" && print_log "Moved "${BKP_IMG_TS}" image to "${BACKUP_IMG}" folder" || die "Failed to move "${BKP_IMG_TS}" image to "${BACKUP_IMG}" folder" done else print_log "WARNING: No backup images were found for the main ${VM_IMG} image, skipping it" fi purge_expired "${BACKUP_IMG}" "$(basename ${VM_IMG}).*" "${RETENTION}" done else die "No images were reported by "virsh domblklist ${VM}" command, something is heavily wrong" fi print_log "End backup of VM: ${VM}" done # Cleanup FILES_TO_DELETE="$(find ${BACKUP_DIR} -type f -mtime +${RETENTION})" if [ $(find ${BACKUP_DIR} -type f -mtime +${RETENTION} | wc -l) -gt 1 ]; then print_log "The following copies have expired and will be deleted:n$(find ${BACKUP_DIR} -type f -mtime +${RETENTION})" find ${BACKUP_DIR} -type f -mtime +${RETENTION} -delete && print_log "Expired copies were successfully deleted" || die "Could not delete expired copies" fi print_log "=== END BACKUP OF THE HOST: $(hostname) ===" Example of the log: 20221116 12:12:28 - === START BACKUP OF THE HOST: kvm === 20221116 12:12:28 - Running VMs to be backed up: int 20221116 12:12:28 - Start backup of VM: int 20221116 12:12:28 - Dumped XML config for "int" VM to /data/_backup/int/config/int.xml.20221116124228 file 20221116 12:12:28 - Expired file /data/_backup/int/config/int.xml.20221116120424 was purged 20221116 12:12:28 - Backup job for the "int" VM has been started 20221116 12:12:04 - Backup job for the "int" VM has finished 20221116 12:12:04 - Found backup image /data/kvm/images/int.img.1668620548 20221116 12:12:04 - Moved "/data/kvm/images/int.img.1668620548.20221116124228" image to "/data/_backup/int/images" folder 20221116 12:12:04 - Expired file /data/_backup/int/images/int.img.1668618264.20221116120424 was purged 20221116 12:12:04 - Found backup image /data/kvm/images/int-data.img.1668620548 20221116 12:12:04 - Moved "/data/kvm/images/int-data.img.1668620548.20221116124228" image to "/data/_backup/int/images" folder 20221116 12:12:04 - Expired file /data/_backup/int/images/int-data.img.1668618264.20221116120424 was purged 20221116 12:12:04 - End backup of VM: int 20221116 12:12:04 - === END BACKUP OF THE HOST: kvm === |
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1999-2024 (C) Vladislav Staroselskiy
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