Rotating LVM snapshots for shadow copy
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#!/bin/bash # # written by Christian Schwamborn # bugs and suggestions to: # christian.schwamborn[you-know-what-comes-here]nswit.de # # published under GNU General Public License v.2 # version 1.0.2 (2007-01-08) # # History: # 1.0.1 (2006-11-21) initial release # 1.0.2 (2007-01-08) snapshottime now in GMT # # You are using this scrip at your own risk, the author is not responsible # for data damage or losses in any way. # # What this is: # You can use this script to create and manage snapshots for the Samba # VFS module shadow_copy. # # How to use: # The script provides some commanline parameters which are usefull for # start/stop scrips (i.e. mount and unmount). Other parameters are usefull # for cronjobs - add this, for a usual snapshot scenario (without trailing #) # to your crontab: # # 0 12 * * 1-5 root /usr/local/sbin/smbsnap autosnap 0 0 # 0 7 * * 2-5 root /usr/local/sbin/smbsnap autosnap 0 1 # 0 7 * * 1 root /usr/local/sbin/smbsnap autosnap 0 2 # 3,33 * * * * root /usr/local/sbin/smbsnap autoresize all # # This takes snapshots at 7:00 and 12:00 every workday and checks every hour # if a snapshot needs to be resized. # # The script has some flaws: # -This script currently works only with LVM2, no EVMS support yet # -XFS should be easy to implement, but it isn't yet # -You must not use dashes in your volumegroups or logical volumes # -Be carefull with the configuration, the parameters are not completely # checked right now, as the same for the command line parameters # -You have to keep track of the freespace of your volumegroups # -Be aware, that if your snapshots grow faster than you assumed, they will # become unusable. With the configuration shown above, this script checks # every 30 minutes if the snapshots are in the need of a resize. If # someone has a better idea how to check the snapshots than periodical, # let me know plaese. # # This script is written for the bash, other shells might work, it also uses # some external commands: mount, umount, grep, date, bc, logger, lvcreate, # lvremove, lvresize # # There are currently three variables that have to be configured: # -SnapVolumes is an array, every element of that array represents a logical # volume that is configured for snapshots. Each element is a comma seperated # list, which consists of the logical volume itself (i.e. /dev/GROUP1/foo), # the start size of the snapshot (in megabytes), the freespace which should # be maintained (in megabytes) and the space added, when a snapshot is # resized (also in megabytes). # The number of an element is used as a reference when calling the script # -SnapSets is also an array, currently every element just represents the # age (in days) of a snapshot of the specific snapshot-set. # -OffDays is a simple string with the none work days. # # The script will figure out by itself where to mount the snapshots, but the # original logical volumes has to be mounted fist. # # Copy and adjust the following three variables (without #) to a blank file in # /etc/samba and name it smbsnap.conf. If you place the configuration file # elsewhere, make sure to adjust the path below. # # SnapVolumes=('/dev/GROUP/foo,2000,500,1000' '/dev/GROUP/bar,3000,1000,2000') # SnapSets=(2 5 20) # OffDays="Sat Sun" # ############################################################################### . /etc/samba/smbsnap.conf export LANG=en_US.UTF-8 export LANGUAGE=en_US:en SnapDate=$(date -u +%Y.%m.%d-%H.%M).00 [ -z "${1}" ] || Command=${1} [ -z "${2}" ] || LVolume=${2} [ -z "${3}" ] || SnapSet=${3} # process a single snapshot # arguments: Command # needs: SnapShot, VolumePath, SnapSets, OffDays, FreeSize, ReSize # provides: na. # local: cmd, SnapShotPath, CurrSnapSets, Count, Expire, Parameters, SnapState, CurrSize, FillPercet, CurrFreeSize function DoSnap() { cmd=${1} SnapShotPath=${VolumePath}/@GMT-$(echo ${SnapShot##*/} | cut -f3-4 -d\-) case ${cmd} in # to mount snapshots mount) [ -d ${SnapShotPath} ] || mkdir ${SnapShotPath} || \ logger "${0}: ***error*** - unable to create mountpoint for ${SnapShot}" if mount | grep -q ${SnapShotPath}; then logger "${0}: ***error*** - snapshot ${SnapShot} is allready mounted to ${SnapShotPath}" else mount ${SnapShot} ${SnapShotPath} -o ro >/dev/null 2>&1 || \ logger "${0}: ***error*** - can not mount ${SnapShot} to ${SnapShotPath}" fi ;; # to unmount a snapshots umount) if mount | grep -q ${SnapShotPath}; then umount -f -l ${SnapShotPath} >/dev/null 2>&1 || \ logger "${0}: ***error*** - can not unmount ${SnapShot} mounted to ${SnapShotPath}" else logger "${0}: ***error*** - snapshot ${SnapShot} is not mounted to ${SnapShotPath}" fi ;; # to remove expired snapshots clean) CurrSnapSet=$(echo ${SnapShot##*/} | cut -f2 -d\-) if [ ${CurrSnapSet} -ge 0 ] && [ ${CurrSnapSet} -lt ${#SnapSets[@]} ]; then Expire=$(echo ${SnapSets[${CurrSnapSet}]} | cut -f1 -d,) # add off-days, if any, to the expire time; we just count work-days declare -i Count=1 while [ ${Expire} -ge ${Count} ];do echo ${OffDays} | grep -q $(date -d "-${Count} day" +%a) && Expire=$((${Expire} + 1)) Count=$((${Count} + 1)) done # compare date now minus expire-time with the snapshot-date if [ $(( $(date +%s) - ${Expire}*24*60*60 - 12*60*60)) -gt \ $(date -d "$(echo ${SnapShot##*/} | cut -f3 -d\- | tr \. \-) \ $(echo ${SnapShot##*/} | cut -f4 -d\- | tr \. \:)" +%s) ]; then # unmount snapshot if mount | grep -q ${SnapShotPath}; then umount -f ${SnapShotPath} >/dev/null 2>&1 || \ logger "${0}: ***error*** - can not unmount ${SnapShot} mounted to ${SnapShotPath}" fi if ! mount | grep -q ${SnapShotPath}; then # remove mount-directory if [ -d ${SnapShotPath} ]; then rmdir ${SnapShotPath} || \ logger "${0}: ***error*** - unable to remove mountpoint for ${SnapShot}" fi # finally remove snapshot if lvremove -f ${SnapShot} >/dev/null 2>&1;then logger "${0}: successfully removed outdated snapshot ${SnapShot}" else logger "${0}: ***error*** - can not remove logical volume ${SnapShot}" fi fi fi else logger "${0}: ***error*** - snapshot-set #${CurrSnapSet} of snaphot ${SnapShot} is not configured" fi ;; # to check periodical if the snapshots have to be resized autoresize) Parameters="--options lv_size,snap_percent --noheadings --nosuffix --separator , --unbuffered --units m" SnapState=$(lvs ${Parameters} ${SnapShot}) CurrSize=$(echo ${SnapState} | cut -f1 -d,) FillPercet=$(echo ${SnapState} | cut -f2 -d,) CurrFreeSize=$(echo "${CurrSize}-${CurrSize}/100*${FillPercet}" | bc) if ! [ $(echo "${CurrFreeSize} > ${FreeSize}" | bc) -eq 1 ]; then if lvresize -L +${ReSize}M ${SnapShot} >/dev/null 2>&1; then logger "${0}: successfully resized snapshot ${SnapShot}" else logger "${0}: ***error*** - an error occurred while resizing ${SnapShot}" fi fi ;; esac } # invoked if all snapshots of a volume are processed # arguments: Command # needs: VolumeDevice, VolumePath, SnapSet & functions: DoSnap # provides: SnapShot # local: snapset_tmp, cmd function DoAllSnaps() { cmd=${1} [ -z "${SnapSet}" ] || snapset_tmp="${SnapSet}-" # checkout if the configured volume exists and is mounted if [ -b ${VolumeDevice} ]; then if mount | grep -q "${VolumePath} "; then # process all snapshots of the volume and, if given, of a specific snapshot-set for SnapShot in ${VolumeDevice}-${snapset_tmp}*; do if [ ${SnapShot} = "${VolumeDevice}-${snapset_tmp}*" ]; then logger "${0}: ***error*** - no backupset #${SnapSet} found for ${VolumeDevice}" else DoSnap ${cmd} fi done else logger "${0}: ***error*** - logical volume ${VolumeDevice} not mounted to ${VolumePath}" fi else logger "${0}: ***error*** - logical volume ${VolumeDevice} does not exist" fi } # creates a new snapshot and mounts it # arguments: na. # needs: VolumeDevice, VolumePath, SnapSet, SnapSize, SnapDate & functions: DoAllSnaps, DoSnap # provides: SnapShot # local: na. function MakeSnap () { case ${SnapSet} in [0-9]) if [ "${Command}" = "autosnap" ]; then DoAllSnaps "clean"; fi SnapShot=${VolumeDevice}-${SnapSet}-${SnapDate} if lvcreate -L${SnapSize}M -s -n ${SnapShot##*/} ${VolumeDevice} >/dev/null 2>&1; then logger "${0}: successfully created new snapshot ${SnapShot}" else logger "${0}: ***error*** - an error occurred while creating snapshot ${SnapShot}" fi DoSnap "mount" ;; *) echo "usage: ${0} snap|autosnap <LV number | all> <Snap-Set Number>" ;; esac } # sets some variables and splits the way for certain commands # arguments: one object of the array SnapVolumes # needs: Command, & functions: DoAllSnaps MakeSnap # provides: SnapVolume, VolumeDevice, PVGroupName, LVolumeName, VolumePath, SnapSize, FreeSize, ReSize # local: na. function SecondChoice () { SnapVolume=${1} VolumeDevice=$(echo ${SnapVolume} | cut -f1 -d,) PVGroupName=$(echo ${VolumeDevice} | cut -f3 -d/) LVolumeName=$(echo ${VolumeDevice} | cut -f4 -d/) VolumePath=$(mount | grep ^/dev[[:alnum:]/]*${PVGroupName}.${LVolumeName}[\ ] | cut -f3 -d' ') SnapSize=$(echo ${SnapVolume} | cut -f2 -d,) FreeSize=$(echo ${SnapVolume} | cut -f3 -d,) ReSize=$(echo ${SnapVolume} | cut -f4 -d,) case ${Command} in mount|umount|clean|autoresize) DoAllSnaps ${Command} ;; snap|autosnap) MakeSnap ;; esac } # decides if all configured volumes are processed or just a specific one # arguments: na. # needs: Command, LVolume, SnapVolumes & functions: SecondChoice # provides: na. # local: snp case ${Command} in mount|umount|snap|clean|autosnap|autoresize) case ${LVolume} in all) for snp in ${SnapVolumes[@]}; do SecondChoice ${snp} done ;; [0-9]) if [ ${LVolume} -ge 0 ] && [ ${LVolume} -lt ${#SnapVolumes[@]} ]; then SecondChoice ${SnapVolumes[LVolume]} else logger "${0}: ***error*** - there is no configured logical volume #${LVolume} for snapshots" fi ;; *) echo "usage: ${0} <command> <LV number | all> [<Snap-Set Number>]" ;; esac ;; *) echo "usage: ${0} <command> <LV number | all> [<Snap-Set Number>]" echo echo " valid commands are:" echo " mount - to mount snapshots" echo " umount - to unmount snapshots" echo " snap - to make a new snapshot" echo " clean - to cleanup outdated snapshots" echo " autosnap - normally used for cronjobs to cleanup" echo " outdates snapshots an create a new one" echo " autoresize - for a periodical check if snapshots" echo " needs to be resized" echo echo " <LV number> is the number of a logical volume, configured for" echo " snapshots in SnapVolumes, or simply 'all' for all volumes" echo " <Snap-Set Number> is the number of the snapshot-set, configured" echo " in SnapSet. It is optional, except for the commands 'snap' and" echo " 'autosnap'" echo ;; esac