使用LVM对Mongodb进行速度快照和压缩备份

engins

这里使用LVM 逻辑磁盘对 Mongodb进行超速备份，mongodb到了几十G以上，用mongodb工具备份的速度，会让我们感到相当蛋疼的慢，这时候我们可以进行mongdb的data目录进行LVM快照备份。

原理：通过lvm快照给lvm真身拍个照片，当lvm真身发送改变时，lvm快照把lvm真身改变之前的内容存放在快照上，这样在lvm快照有效的这段时间内，我们看到的lvm快照上的内容始终是lvm真身在创建lvm快照时内容，通过备份lvm快照即可达到在线备份lvm真身的目的。需要注意的是，当lvm快照比lvm真身小时，若lvm真身发生的改变大于lvm快照，则lvm快照将变得无法读取而失效; 若lvm快照大于等于lvm真身，则不会发生前面的情况。

用法：

-g 是VG组     -v 是具体的lv逻辑盘

• ./mongolvmbackup.sh -g myvolgroup -v mongodata
  

地址： http://rfyiamcool.blog.

脚本：

• [Shell] 纯文本查看 复制代码

  #!/bin/bash -e 
   
  # Backup the local MongoDB database by: 
  # 
  #  
  #  1  lvm snapshot mongodb's data volume 
  #  2  unlock mongodb 
  #  3   bzip2 the snapshot into tempdir 
   
  #在压缩的备份将暂时分级传输 
   
  TARGET_DIR=/mnt/mongosnaps 
   
  #保留的天数 
  LOCAL_RETENTION_DAYS=7 
   
  #压缩的等级 
  COMPRESS_PROG=bzip2 
  COMPRESS_SUFFIX=tbz2 
  COMPRESS_LEVEL=6 
   
   
  print_help() { 
    echo 
    echo "$0: -g <lvmgroup> -v <lvmvolume> -b <s3 bucket>" 
    echo 
    echo "Snapshot & compress MongoDB databases present on this host.  Place them in" 
    echo "$TARGET_DIR and create a 'latest' symlink." 
    echo 
    exit 0 
  } 
   
   
  # Check for some required utilities 
  command lvcreate --help >/dev/null 2>&1 || { echo "Error: lvcreate is required.  Cannot continue."; exit 1; } 
  command lvremove --help >/dev/null 2>&1 || { echo "Error: lvremove is required.  Cannot continue."; exit 1; } 
  command $COMPRESS_PROG -V >/dev/null 2>&1 || { echo "Error: compression util required.  Cannot continue."; exit 1; } 
   
   
  s3bucket='' 
  vgroup='' 
  volume='' 
   
  while [ $# -gt 0 ] 
  do 
    case $1 in 
      -h) print_help ;; 
      --help) print_help ;; 
      -b) s3bucket=$2 ; shift 2 ;; 
      -g) vgroup=$2 ; shift 2 ;; 
      -v) volume=$2 ; shift 2 ;; 
      *) shift 1 ;; 
    esac 
  done 
   
   
  #检查卷 
  if [ "$vgroup" == "" ] 
  then 
    echo "No group set, won't continue" 
    exit 1 
  fi 
  if [ "$volume" == "" ] 
  then 
    echo "No volume set, won't continue" 
    exit 1 
  fi 
   
   
  # Check volume is a real LVM volume 
  if ! lvdisplay "/dev/$vgroup/$volume" >/dev/null 2>/dev/null 
  then 
    echo "/dev/$vgroup/$volume is not a real LVM volume!" 
    exit 1 
  fi 
   
   
  # Figure out where to put it 
  date=`date +%F_%H%M` 
  targetfile="${volume}-${date}-snap.${COMPRESS_SUFFIX}" 
   
   
  # ============================================================================= 
  # Print a meaningful banner! 
   
   
  echo "==================== LVM MONGODB SNAPSHOT SCRIPT =====================" 
  echo 
  echo "  Snapshotting: /dev/${vgroup}/${volume}" 
  echo "  Target:       ${TARGET_DIR}/${targetfile}" 
  echo 
   
  #如果目标文件夹不存在的话，创建 
  if [ ! -d "$TARGET_DIR" ] 
  then 
    echo "Your target dir ${TARGET_DIR} doesn't exist and I'm too cowardly to create it" 
    exit 1 
  fi 
   
   
  # 创建快照 
  snapvol="$volume-snap" 
  echo "Freezing MongoDB before LVM snapshot" 
  mongo -eval "db.fsyncLock()" 
  echo 
  echo "Taking snapshot $snapvol" 
  lvcreate --snapshot "/dev/$vgroup/$volume" --name "$snapvol" --extents '90%FREE' 
  echo 
  echo "Snapshot OK; unfreezing DB" 
  mongo -eval "db.fsyncUnlock()" 
  echo 
  echo 
   
  # 挂载LVM快照 
  mountpoint=`mktemp -t -d mount.mongolvmbackup_XXX` 
  mount -v -o ro "/dev/${vgroup}/${snapvol}" "${mountpoint}" 
  echo 
   
   
  find "$TARGET_DIR" -iname "*-snap.${COMPRESS_SUFFIX}" -mtime +${LOCAL_RETENTION_DAYS} -delete 
  echo 
   
  # 按照我们先前设置的比率进行压缩 
  echo "Compressing snapshot into ${TARGET_DIR}/${targetfile}" 
  cd "${mountpoint}" 
  tar cv * | $COMPRESS_PROG "-${COMPRESS_LEVEL}" -c > "${TARGET_DIR}/${targetfile}" 
  echo 
  cd - 
  cd "$TARGET_DIR" 
  rm -vf latest.${COMPRESS_SUFFIX} 
  ln -v -s ${targetfile} latest.${COMPRESS_SUFFIX} 
  cd - 
   
  echo 
  echo 
   
  # 卸载并删除用于备份的那个快照 
  echo "Removing temporary volume..." 
  umount -v "$mountpoint" 
  rm -rvf "$mountpoint" 
  echo 
  lvremove -f "/dev/${vgroup}/${snapvol}" 
  echo 
  echo 

  
  

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