在 FreeBSD 8 對 UFS filesystem 做 snapshot

1. 在 crontab 定期做 snapshot

### UFS snapshot
0    1      *       *       *       root    /usr/local/sbin/snapshot make -g7 /SRCPATH:Daily
0      2      *       *       1       root    /usr/local/sbin/snapshot make -g4 /SRCPATH:Weekly

2. 掛載 UFS snapshot 的 shell script

#!/usr/local/bin/bash

PATH=$PATH
CHKPARA=0

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

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

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

if [ $CHKPARA -eq 1 ]; then
        echo "Usage: $0 Snapshot_Src_Path SnapshotName MountPath"
        echo "Example: $0 /:Weekly.0 /mnt"
        exit 1
else
        echo "Try to mount $SSSRCPATH:$SnapshotName to $MountPath now."
fi

MC=`df -h |grep $MountPath |wc -l`

if [ -d $SSSRCPATH ]; then
        if [ -f $SSSRCPATH/.snap/$SnapshotName ]; then
                if [ -d $MountPath ]; then
                        if [ $MC -gt 0 ]; then
                                echo "MountPath $MountPath had been mounted!"
                        else
                                snapshot mount $SSSRCPATH:$SnapshotName $MountPath
                                df -h |grep $MountPath
                                echo "MountPath $MountPath was mounted."
                        fi
                else
                        echo "MountPath $MountPath does not existed!"
                fi
        else
                echo "Snapshot $SSSRCPATH/.snap/$SnapshotName does not existed!"
        fi
else
        echo "Snapshot source path $SSSRCPATH does not existed!"
fi

3. 掛載範例

# mkdir -p /SNAPSHOT/Mount/Path/Weekly0

/PATH/TO/mount_UFS_snapshot.sh /SRCPATH Weekly.0 /SNAPSHOT/Mount/Path/Weekly0

4. 卸載 UFS snapshot 的 shell script

#!/usr/local/bin/bash

PATH=$PATH
CHKPARA=0

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

if [ $CHKPARA -eq 1 ]; then
        echo "Usage: $0 MountPath"
        echo "Example: $0 /mnt"
        exit 1
else
        echo "Try to umount $MountPath now."
fi

MC=`df -h |grep $MountPath |wc -l`

if [ -d $MountPath ]; then
        if [ $MC -gt 0 ]; then
                snapshot umount $MountPath
                df -h |grep $MountPath
                echo "MountPath $MountPath had been umounted!"
        else
                echo "MountPath $MountPath had not been mounted!"
        fi
else
        echo "MountPath $MountPath does not existed!"
fi

5. 卸載範例

/PATH/TO/umount_UFS_snapshot.sh /SNAPSHOT/Mount/Path/Weekly0

6. UFS 做 snapshot 速度還蠻慢的. (相較於 ZFS 的快速完成 snapshot)

參考資料
FreeBSD UFS/ZFS Snapshot Management Environment