13.2.2 Backing-up entire file system

To back up the GFS Shared File System in file system unit, use dd(1). The following describes the backing-up procedure using dd(1).

See

For details about dd(1), see the online manual.

Entire-file-system backing-up allows backing-up of the entire file system more quickly than file-by-file backing-up. However, a file system backed up with this method cannot be restored on a file-by-file basis during restoring.

Before executing backing-up, use the following procedure to check the partition information for the desired GFS Shared File System. Estimate the backing-up media capacity required for backing-up and the number of required media and then unmount of the GFS Shared File System.

The following describes examples of tape backup in case of single partition configuration and multi-partition configuration.

For a single partition configuration

Use sfcinfo(8) to display partition information and check that the file system has only a single partition (same special file names) and that the capacity of the device, backup destination, is sufficient. The size of the partition can be estimated by adding 1 megabyte to the sum of the values displayed in the size field (in kilobytes).

Example: Backup in case of single partition

# sfcinfo /dev/sfdsk/gfs01/dsk/volume01 <Enter>
FSID special                                      size  Type  mount
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)        14422  META  -----
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)         5116  LOG   -----
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)        95112  DATA  -----
# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k <Enter>

For a multi-partition configuration

dd(1) can handle one partition at a time. For a multi-partition configuration, therefore, the partitions must be backed up one at a time. Use sfcinfo(8) to check the partition configuration then back up each partition with the same procedure as used for a single partition configuration.

Example: Backup in case of two partitions

# sfcinfo /dev/sfdsk/gfs01/dsk/volume01 <Enter>
FSID special                                      size  Type  mount
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)        14422  META  -----
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)         5116  LOG   -----
   1 /dev/sfdsk/gfs01/dsk/volume01(1e756)        95112  DATA  -----
   1 /dev/sfdsk/gfs01/dsk/volume02(1e757)        95112  DATA  -----
# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k <Enter>
  (Change tape)
# dd if=/dev/sfdsk/gfs01/dsk/volume02 of=/dev/st0 bs=1024k <Enter>

Note

All the partitions including the relevant GFS Shared File System must be backed up.
The tapes used for backups must be labeled so that the backed up partitions can be identified. They must then be stored as a set.

dd(1) does not support multi-tape volumes. If the file system is too large to fit on a single tape, data needs to be divided and backed up. In such cases, set bs (block length) and count (number of blocks) and increase skip (input-side offset (number of blocks)) by the value of count.

Example: Backup in case of separating partition as blocks in units of 1 gigabyte

# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k count=1024 <Enter>
  (Change tape)
# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k count=1024 skip=1024 <Enter>
  (Change tape) 
# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k count=1024 skip=2048 <Enter>
  (Change tape)
# dd if=/dev/sfdsk/gfs01/dsk/volume01 of=/dev/st0 bs=1024k count=1024 skip=3072 <Enter>
  ...