When you use the fssnap command to create a file-system snapshot, observe how much disk space the backing-store file consumes. The backing-store file uses no space, and then it grows quickly, especially on heavily used systems. Make sure the backing-store file has enough space to grow, or limit its size with the -o maxsize=n [k,m,g] option, where n [k,m,g] is the maximum size of the backing-store file.
If the backing-store file runs out of space, the snapshot might delete itself, which causes the backup to fail. Check the /var/adm/messages file for possible snapshot errors.
Become superuser.
Make sure there is enough disk space for the backing-store file.
# df -k |
Make sure that a backing-store file of the same name and location does not already exist.
# ls /file-system/backing-store-file |
Create the file-system snapshot.
# fssnap -F ufs -o bs=/file-system/backing-store-file /file-system |
The following example creates a snapshot of the /usr file system. The backing-store file is /scratch/usr.back.file, and the virtual device is /dev/fssnap/1.
# fssnap -F ufs -o bs=/scratch/usr.back.file /usr /dev/fssnap/1 |
The following example limits the backing-store file to 500 Mbytes.
# fssnap -F ufs -o maxsize=500m,bs=/scratch/usr.back.file /export/home /dev/fssnap/1 |
You can display the current snapshots on the system by using the fssnap -i option. If you specify a file system, you see detailed information about that snapshot. If you don't specify a file system, you see information about all of the current file system snapshots and their corresponding virtual devices.
Become superuser.
List current snapshots.
# fssnap -i 0 / 1 /usr |
To display detailed information about a specific snapshot, use the following:
# fssnap -i /usr Snapshot number : 1 Block Device : /dev/fssnap/1 Raw Device : /dev/rfssnap/1 Mount point : /usr Device state : idle Backing store path : /scratch/usr.back.file Backing store size : 480 KB Maximum backing store size : Unlimited Snapshot create time : Tue Aug 08 09:57:07 2000 Copy-on-write granularity : 32 KB |