Creating a UFS Snapshot
Use fssnap command to create, query, or delete temporary read-only snapshots of ufs file systems.
Syntax to create a UFS snapshot:
# fssnap -F ufs -o bs=backing_store_path /file-system
Note – The backing_store_path can be a raw device, the name of an existing directory, or the name of a file that does not already exist.
Example:
# fssnap -F ufs -o bs=/var/tmp /export/home ==> to create a snapshot of
/export/home file system
Limiting the Size of the Backing-Store File
To limit the backing-store file to 500 Mbytes
# fssnap -F ufs -o bs=/var/tmp,maxsize=500m /export/home
Displaying Information for a ufs File System Snapshot
# fssnap -i ==> to list all current UFS snapshots on the system
# /usr/lib/fs/ufs/fssnap -i /export/home ==> to display detailed
information for a specific UFS snapshot
Backing Up the UFS Snapshot File
Use the tar command or the ufsdump command to back up a UFS snapshot.
Using the tar Command to Back Up a Snapshot File
Mount the snapshot before backing it up
1. Create the mount point for the block virtual device.
# mkdir -p /backups/home.bkup
2. Mount the block virtual device to the mount point.
# mount -F ufs -o ro /dev/fssnap/0 /backups/home.bkup
3. Change directory to the mount point.
# cd /backups/home.bkup
4. Use the tar command to write the data to tape.
# tar cvf /dev/rmt/0 .
Using the ufsdump Command
Specify the raw virtual device during the backup
# ufsdump 0uf /dev/rmt/0 /dev/rfssnap/0
# ufsdump 0ufN /dev/rmt/0 /dev/rdsk/c0d1s7 /dev/rfssnap/0
Verify that the UFS snapshot is backed up.
# ufsrestore tf /dev/rmt/0 ==> t - to list the table of contents of the backup media
Performing an Incremental Backup Using a UFS Snapshot
To create an incremental backup of a snapshot
# ufsdump 1ufN /dev/rmt/0 /dev/rdsk/c0d1s7 /dev/rfssnap/0
Use the ufsdump command with the N option to create an incremental UFS snapshot, which writes the name of the device being backed up, rather than the name of the snapshot device to the /etc/dumpdates file.
Note – It is important to note the use of the N argument when backing up
a snapshot. This argument ensures proper updates to the /etc/dumpdates file.
To verify that the UFS snapshot is backed up to tape
# ufsrestore tf /dev/rmt/0
Performing incremental backups of snapshots
1. Create a snapshot of the /extra file system that is going to be
backed up while the file system is mounted.
# fssnap -o bs=/var/tmp /extra
2. Verify that the snapshot was successful, and view detailed
information about the snapshot.
# fssnap -i
# /usr/lib/fs/ufs/fssnap -i /extra
3. Make a directory that will be used to mount and view the snapshot
data.
# mkdir /extrasnap
4. Mount the snapshot to the new mount point, and compare the size of
the file system and the snapshot device.
# mount -o ro /dev/fssnap/0 /extrasnap
# df -k | grep extra
/dev/dsk/c0d1s3 1294023 9 1242254 1% /extra
/dev/fssnap/0 1294023 9 1242254 1% /extrasnap
5. Edit a file under the /extra directory and make it larger, and then
compare the size of the file system and the snapshot device.
# df -k |grep extra
/dev/dsk/c0d1s3 1294023 20 1242243 1% /extra
/dev/fssnap/0 1294023 9 1242254 1% /extrasnap
Observe that the file system grew in size while the snapshot file did not.
6. Perform a full backup with the N option of the ufsdump command.
# ufsdump 0ufN /dev/rmt/0 /dev/rdsk/c0d1s3 /dev/rfssnap/0
7. Verify the backup.
# ufsrestore tf /dev/rmt/0
8. Unmount the back up device and remove the snapshot & backing-store file.
# umount /extrasnap
# fssnap -d /extra
# rm /var/tmp/snapshot0
9. Make some changes to the /extra file system, such as copying some
files, and then re-create the snapshot.
# fssnap -o bs=/var/tmp /extra
10. Re-mount the snapshot device, and compare the size of the file
system and the snapshot device.
# mount -o ro /dev/fssnap/0 /extrasnap
# df -k | grep extra
/dev/dsk/c0d1s3 1294023 46 1242217 1% /extra
/dev/fssnap/0 1294023 46 1242217 1% /extrasnap
11. Perform an incremental backup with the N option of the ufsdump
command.
# ufsdump 1ufN /dev/rmt/0 /dev/rdsk/c0d1s3 /dev/rfssnap/0
12. Verify the backup.
# ufsrestore tf /dev/rmt/0
Notice that the backup of the snapshot contains only the files that were added since the previous Level 0 backup.
Restoring Data From a UFS Snapshot Backup
Data written to a tape by ufsdump is simply data, whether it is a snapshot or a file system.
Restore a UFS snapshot from a backup tape in the same manner as you would from the backup of an original file system.
Deleting a UFS Snapshot
1. First, unmount the snapshot device
2. Delete the snapshot
3. Finally remove the backing-store file.
# umount /dev/fssnap/0
# fssnap -d /export/home
# rm /backing_store_file
Use fssnap command to create, query, or delete temporary read-only snapshots of ufs file systems.
Syntax to create a UFS snapshot:
# fssnap -F ufs -o bs=backing_store_path /file-system
Note – The backing_store_path can be a raw device, the name of an existing directory, or the name of a file that does not already exist.
Example:
# fssnap -F ufs -o bs=/var/tmp /export/home ==> to create a snapshot of
/export/home file system
Limiting the Size of the Backing-Store File
To limit the backing-store file to 500 Mbytes
# fssnap -F ufs -o bs=/var/tmp,maxsize=500m /export/home
Displaying Information for a ufs File System Snapshot
# fssnap -i ==> to list all current UFS snapshots on the system
# /usr/lib/fs/ufs/fssnap -i /export/home ==> to display detailed
information for a specific UFS snapshot
Backing Up the UFS Snapshot File
Use the tar command or the ufsdump command to back up a UFS snapshot.
Using the tar Command to Back Up a Snapshot File
Mount the snapshot before backing it up
1. Create the mount point for the block virtual device.
# mkdir -p /backups/home.bkup
2. Mount the block virtual device to the mount point.
# mount -F ufs -o ro /dev/fssnap/0 /backups/home.bkup
3. Change directory to the mount point.
# cd /backups/home.bkup
4. Use the tar command to write the data to tape.
# tar cvf /dev/rmt/0 .
Using the ufsdump Command
Specify the raw virtual device during the backup
# ufsdump 0uf /dev/rmt/0 /dev/rfssnap/0
# ufsdump 0ufN /dev/rmt/0 /dev/rdsk/c0d1s7 /dev/rfssnap/0
Verify that the UFS snapshot is backed up.
# ufsrestore tf /dev/rmt/0 ==> t - to list the table of contents of the backup media
Performing an Incremental Backup Using a UFS Snapshot
To create an incremental backup of a snapshot
# ufsdump 1ufN /dev/rmt/0 /dev/rdsk/c0d1s7 /dev/rfssnap/0
Use the ufsdump command with the N option to create an incremental UFS snapshot, which writes the name of the device being backed up, rather than the name of the snapshot device to the /etc/dumpdates file.
Note – It is important to note the use of the N argument when backing up
a snapshot. This argument ensures proper updates to the /etc/dumpdates file.
To verify that the UFS snapshot is backed up to tape
# ufsrestore tf /dev/rmt/0
Performing incremental backups of snapshots
1. Create a snapshot of the /extra file system that is going to be
backed up while the file system is mounted.
# fssnap -o bs=/var/tmp /extra
2. Verify that the snapshot was successful, and view detailed
information about the snapshot.
# fssnap -i
# /usr/lib/fs/ufs/fssnap -i /extra
3. Make a directory that will be used to mount and view the snapshot
data.
# mkdir /extrasnap
4. Mount the snapshot to the new mount point, and compare the size of
the file system and the snapshot device.
# mount -o ro /dev/fssnap/0 /extrasnap
# df -k | grep extra
/dev/dsk/c0d1s3 1294023 9 1242254 1% /extra
/dev/fssnap/0 1294023 9 1242254 1% /extrasnap
5. Edit a file under the /extra directory and make it larger, and then
compare the size of the file system and the snapshot device.
# df -k |grep extra
/dev/dsk/c0d1s3 1294023 20 1242243 1% /extra
/dev/fssnap/0 1294023 9 1242254 1% /extrasnap
Observe that the file system grew in size while the snapshot file did not.
6. Perform a full backup with the N option of the ufsdump command.
# ufsdump 0ufN /dev/rmt/0 /dev/rdsk/c0d1s3 /dev/rfssnap/0
7. Verify the backup.
# ufsrestore tf /dev/rmt/0
8. Unmount the back up device and remove the snapshot & backing-store file.
# umount /extrasnap
# fssnap -d /extra
# rm /var/tmp/snapshot0
9. Make some changes to the /extra file system, such as copying some
files, and then re-create the snapshot.
# fssnap -o bs=/var/tmp /extra
10. Re-mount the snapshot device, and compare the size of the file
system and the snapshot device.
# mount -o ro /dev/fssnap/0 /extrasnap
# df -k | grep extra
/dev/dsk/c0d1s3 1294023 46 1242217 1% /extra
/dev/fssnap/0 1294023 46 1242217 1% /extrasnap
11. Perform an incremental backup with the N option of the ufsdump
command.
# ufsdump 1ufN /dev/rmt/0 /dev/rdsk/c0d1s3 /dev/rfssnap/0
12. Verify the backup.
# ufsrestore tf /dev/rmt/0
Notice that the backup of the snapshot contains only the files that were added since the previous Level 0 backup.
Restoring Data From a UFS Snapshot Backup
Data written to a tape by ufsdump is simply data, whether it is a snapshot or a file system.
Restore a UFS snapshot from a backup tape in the same manner as you would from the backup of an original file system.
Deleting a UFS Snapshot
1. First, unmount the snapshot device
2. Delete the snapshot
3. Finally remove the backing-store file.
# umount /dev/fssnap/0
# fssnap -d /export/home
# rm /backing_store_file
No comments:
Post a Comment