使用 crontab 管理 ZFS snapshot

近期終於將之前延遲已久的 ZFS storage 計畫實現. 已試過當 raidz 硬碟發生問題時, 使用 zfs replace 更換硬碟. 當然就會想用 snapshot 這個重要的功能. 所以就動手寫了簡單的 shell script 搭配 crontab 做自動化管理.

1. 簡單指令

觀察 zpool 清單, 狀態
   # zpool list
   # zpool status

   觀察 ZFS volume 清單
   # zfs list

   觀察 snapshot 清單 (/usr/ports/sysutils/freebsd-snapshot)
   # snapshot list

2. shell script

#!/usr/local/bin/bash

PATH=$PATH

LOGFILE="/var/log/snapshotfs.log"
TODAY=`date +"%Y%m%d"`
CHKPARA=0

if [ -n "$1" ]; then
 fstype="$1"
 shift
else
 CHKPARA=1
fi


if [ -n "$1" ]; then
 sstype="$1"
 shift
else
 CHKPARA=1
fi


if [ -n "$1" ]; then
 maxnum="$1"
 shift
else
 CHKPARA=1
fi


if [ -n "$1" ]; then
 volpath="$1"
 shift
else
 CHKPARA=1
fi

if [ $CHKPARA -eq 1 ]; then
 echo "Usage: $0 fstype sstype maxnum /filesystem|volume_path"
 echo "Example: $0 zfs [H|D|W|M|Q|Y] 7 /databackup/backup"
 exit 1
else
 touch $LOGFILE
 echo `date +"%Y/%m/%d %H:%M:%S"` >> $LOGFILE
 echo "$0 $fstype $sstype $maxnum $volpath" >> $LOGFILE
 echo "Check parameters for taking a snapshot of $volpath($fstype)." >> $LOGFILE
fi

if [ -d $volpath ]; then
 if [ $fstype = 'zfs' ]; then
  if [ -d $volpath/.zfs/snapshot ]; then
   echo "Check path : OK" >> $LOGFILE
  else
   echo "Check path : Failed, snapshot folder does not exist." >> $LOGFILE
   exit 1
  fi
 elif [ $fstype = 'ufs' ]; then
  if [ -d $volpath/.snap ]; then
   echo "Check path : OK" >> $LOGFILE
  else
   echo "Check path : Failed, snapshot folder does not exist." >> $LOGFILE
   exit 1
  fi
 else
  echo "Unsupported file system $fstype" >> $LOGFILE
  exit 1
 fi
else
 echo "Check path : Failed, filesystem|volume_path does not exist." >> $LOGFILE
 exit 1
fi

if [ $maxnum -gt 0 ]; then
 echo "Check maxnum : OK" >> $LOGFILE
else
 echo "Check maxnum : Failed, must input positive integer." >> $LOGFILE
        exit 1
fi

if [ $fstype = 'zfs' ]; then
 echo "ZFS" >> $LOGFILE

 case $sstype in
 H)  echo "Hourly Snapshot" >> $LOGFILE
   TODAY=`date +"%Y%m%d%H"`
   ;;
 D)  echo "Daily Snapshot" >> $LOGFILE
   ;;
 W)  echo "Weekly Snapshot" >> $LOGFILE
   ;;
 M)  echo "Monthly Snapshot" >> $LOGFILE
   ;;
 Q)  echo "Quaterly Snapshot" >> $LOGFILE
   ;;
 Y)  echo "Yearly Snapshot" >> $LOGFILE
   ;;
 *)  echo "sstype must be H | D | W | M | Q | Y " >> $LOGFILE
   exit 1
 esac

 #Snapshot
 if [ -d $volpath/.zfs/snapshot/$sstype$TODAY ]; then
  echo "Had snapshot($volpath $sstype$TODAY)." >> $LOGFILE
 else
  echo "Take a snapshot of $volpath." >> $LOGFILE
  zfs snapshot `zfs list -H -o name ${volpath}`@${sstype}${TODAY}
 fi

 #Remove more old snapshot

 KEEPSSNUM=$maxnum
 REALSSNUM=`ls $volpath/.zfs/snapshot/ | grep $sstype | wc -l`
 RMSSNUM=`expr $REALSSNUM - $KEEPSSNUM`
 RMSSID=""

 if [ $RMSSNUM -gt 0 ]; then
  for RMSSID in `ls $volpath/.zfs/snapshot/ | grep $sstype | sort -n | head -n $RMSSNUM | sed -e 's/\///'`
  do
   if [ -d $volpath/.zfs/snapshot/$RMSSID ]; then
    echo "Remove old snapshot($volpath $RMSSID)." >> $LOGFILE
    zfs destroy `zfs list -H -o name ${volpath}`@$RMSSID
   else
    echo "Old snapshot($volpath $RMSSID) does not exist." >> $LOGFILE
   fi
  done
 fi

elif [ $fstype = 'ufs' ]; then
 echo "UFS" >> $LOGFILE

 case $sstype in
 H) echo "Hourly Snapshot" >> $LOGFILE
  sskey='Hourly'
  ;;
 D) echo "Daily Snapshot" >> $LOGFILE
  sskey='Daily'
  ;;
 W) echo "Weekly Snapshot" >> $LOGFILE
  sskey='Weekly'
  ;;
 M) echo "Monthly Snapshot" >> $LOGFILE
  sskey='Monthly'
  ;;
 Q) echo "Quaterly Snapshot" >> $LOGFILE
  sskey='Quaterly'
  ;;
 Y) echo "Yearly Snapshot" >> $LOGFILE
  sskey='Yearly'
  ;;
 *) echo "sstype must be H | D | W | M | Q | Y " >> $LOGFILE
  exit 1
 esac
 
 #Snapshot
 echo "Take a snapshot UFS ${volpath}" >> $LOGFILE
 /usr/local/sbin/snapshot make -g${maxnum} ${volpath}:${sskey}
else
 echo "Unsupported file system $fstype" >> $LOGFILE
fi

3. crontab 排程自動化

### ZFS snapshot
### Hourly
45      *       *       *       *       root    /PATH/TO/zfs_snapshot_hourly.sh
### 3 Hourly
50      */3     *       *       *       root    /PATH/TO/zfs_snapshot_3hourly.sh
### Daily
0       23      *       *       *       root    /PATH/TO/zfs_snapshot_daily.sh
### Weekly
20      23      *       *       1       root    /PATH/TO/zfs_snapshot_weekly.sh
### Monthly
40      23      1       *       *       root    /PATH/TO/zfs_snapshot_monthly.sh
### Quaterly
53      23      1       1,4,7,10        *       *       root    /PATH/TO/zfs_snapshot_quaterly.sh
### Yearly
55      23      31      12      *       root    /PATH/TO/zfs_snapshot_yearly.sh


#!/usr/local/bin/bash

PATH=$PATH

### ZFS snapshot               SSTYPE SSCOUNT
### H for hourly or 3hourly ex: H 8
### D for daily             ex: D 7
### W for weekly            ex: W 4
### M for monthly           ex: M 6
### Q for quaterly          ex: Q 4
### Y for yearly            ex: Y 3

/root/root_scripts/snapshotfs.sh zfs SSTYPE SSCOUNT /zfs-volumn/path1
/root/root_scripts/snapshotfs.sh zfs SSTYPE SSCOUNT /zfs-volumn/path2
/root/root_scripts/snapshotfs.sh zfs SSTYPE SSCOUNT /zfs-volumn/path3