Administrator Guide

Variable Name Description Default
During recovery, if this variable is set and if the backup data stream was
generated with this variable turned on, the NDMP server handles deleting
les and directories that are deleted between incremental backups.
Setting this variable requires additional processing time and enlarges the
backup data stream size (how much it changes depends on the number of
elements in the backup data set). If this feature is not important to the end
user, it should not be set.
BASE_DATE Used by TSM for token-based backup, as an alternative to using the LEVEL
environment variable.
When BASE_DATE is set to 00, a full backup is performed.
After a full backup completes, a token can be retrieved by retrieving the
DUMP_DATE environment variable. This token can then be passed in later
backups as the value of BASE_DATE. The backup performed in this case is
an incremental backup relative to the time when the token was generated.
When BASE_DATE is set to -1, token-based backup is disabled.
-1
DEREF_HARD_LINK Controls whether hard link les data content are backed up for all instances
of the same le. Valid values are Y and N.
N
Incremental Backups
Each time a backup is performed, the NDMP server stores the timestamp for the backup. When the NDMP server performs an
incremental backup, it uses the timestamp stored for the previous full or incremental backup to determine if a directory or le needs
to be included.
Both supported backup types (dump and tar) support incremental backup. The algorithm for traversing the backup target directory
is the same. However, because inode-based le history generation has dierent requirements to support DAR, the backup data
stream generated is dierent:
• dump: Each directory visited will be backed up and a le history entry will be generated. It does not matter whether the directory
has changed.
• tar: Backs up and generates a le history entry only for the directories that have changed.
Therefore, the amount of data backed up using a tar backup will be less than that of a dump backup. The size dierence depends on
the number of directories in the backup data set.
NDMP Two-Way Backup
FluidFS supports two-way NDMP congurations where the tape device is directly attached to the data host, either physically or
through a fast internal network. The data service and the tape service both reside on the same NDMP server, and the data
connection is internal to the NDMP server. Both data and tape control commands are communicated through one control
connection from the DMA to the NDMP server.
NOTE: Solutions with iSCSI do not support the direct-attach NDMP feature.
FluidFS Data Protection
439