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Veritas NetBackup™ Administrator's Guide, Volume I

Last Published: 2019-07-01

Product(s): NetBackup (8.2)

UNIX raw partitions

Save a copy of the partition table before a raw partition backup is performed. Retain the copy for reference. To restore the raw partition, make sure that a device file exists. Also, the partition where the table is restored must be large enough or the results of the restore are unpredictable.

Consider the following items when creating UNIX raw partition backups.

File changes during the backup	Use raw partition backups only if you can ensure that the files have not changed in any way during the backup. Or, in the case of a database, if you can restore the database to a consistent state by using transaction log files.
Backup archives	Do not perform backup archives of raw partitions on any client. An archive backs up the raw partition, and then deletes the device file that is associated with the raw partition. The file system does not recover the space that the raw partition uses.
File systems	Before backing up file systems as raw partitions, unmount the file system. Unmounting the file system allows buffered changes to be written to the disk. Also, it prevents the possibility of any changes in the file system during the backup. Use the bpstart_notify and the bpend_notify scripts to unmount and remount the backed-up file systems.
Mount points	The Cross mount points policy attribute has no effect on raw partitions. If the root partition is backed up as a raw partition and contains mount points to other systems, the file systems are not backed up. The other file systems are not backed up, even with Cross mount points selected. The same is true for the Follow NFS policy attribute. NFS file systems that are mounted in a raw partition are not backed up. Nor can you back up raw partitions from other computers by using NFS mounts to access the raw partitions. The devices are not accessible on other computers through NFS.
Disk volume managers	Specify the logical partition names for any disks that disk volume managers manage. (For example, Veritas Volume Manager (VxVM).
FlashBackup policy	For clients in a FlashBackup policy, refer to the NetBackup Snapshot Client Administrator's Guide for the differences between Standard and FlashBackup policies.
Windows Server Failover Clustering (WSFC) environment	The use of FlashBackup in aWindows Server Failover Clustering (WSFC) environment is supported, with the following limitation: Raw partition restores can only be performed when the disk being restored is placed in extended maintenance mode or removed from the WSFC resource group. Note: Early versions of WSFC do not allow extended maintenance mode functionality. If the cluster does not support placing disks in extended maintenance mode, it is still possible to perform raw restores to an alternate, non-shared disk.

If there are no file systems to back up and the disks are used in raw mode, back up the disk partitions as raw partitions. For example, databases are sometimes used in raw mode. Use bpstart_notify and bpend_notify scripts to provide the necessary pre-processing and post-processing of databases when they are backed up as raw partitions.

You can also perform a raw partition backup of a disk partition that is used for file systems. A disadvantage of this method is that you must restore the entire partition to recover a single file (unless FlashBackup is in use). To avoid overwriting the entire partition, use the redirected restore feature to restore the raw partition to another raw partition of the same size. Then, copy individual files to the original file system.

Raw partition backups are also useful for backing up entire disks. Since the file system overhead is bypassed, a raw partition backup is usually faster. The size of the raw partition backup is the size of the entire disk, regardless of whether the entire disk is used.

To specify a UNIX raw partition in the policy backup selection list, enter the full path name of the device file.

For example, on a Solaris system, enter:

/devices/sbus@1,f8000000/esp@0,800000/sd@2,0:1h

Note:

Do not specify wildcards (such as /dev/rsd*) in pathnames for raw partition backups. Doing so can prevent the successful restore of entire devices if there is overlap between the memory partitions for different device files.

You can include raw partitions in the same backup selection list as other backups. For example:

/home
/usr
/etc
/devices/sbus@1,f8000000/esp@0,800000/sd@2,0:1h

Note:

NetBackup does not distinguish between full and incremental backups when it backs up a raw partition. The entire partition is backed up in both cases.

Raw partition backups occur only if the absolute pathname in the backup selection list is a block or character special device file. You can specify either block or character special device files. Character special device files are often faster because character devices avoid the use of the buffer cache for accessed disk data. Test both a block and character special device file to ensure the optimum backup speed for your platform.

Ensure that you specify the actual block-device or character-device files. Sometimes these are links to the actual device files. If a link is specified, only the link is backed up. If the device files are reached while backing up /dev, NetBackup backs up only the inode files for the device, not the device itself.

To perform a raw partition backup, select Full backup for the Type of Backup from the Schedules tab. Any other backup type does not work for backing up raw partitions.

More Information

Cross mount points (policy attribute)

Follow NFS (policy attribute)

Type of backup (schedule attribute)