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Hitachi Vantara Knowledge

NDMP environment variables

You can use NDMP environment variables to modify backup actions. The storage management application generates most of these variables and supports configuration of additional variables. They are invoked from the Replication Rules: Add Rules page.

Direct

Possible value Notes
y or n

Used on recovery to request Direct Access Recovery (DAR).

May be used to recover a subset of a full backup. If the storage management application supports DAR, the recovery will position the tape to the start of the required data rather than reading a complete backup image to find the data. This saves time in recovery of single files and similar operations.

The Storage Management Application may control the setting of this variable, based on either the setting of a user interface option, or on an assessment of the likely efficiency of using DAR; however, in some cases, it may be necessary to explicitly set DIRECT=y.

EXCLUDE

Possible value Notes

Comma-separated list of files or directories

Specifies files or directories to exclude from a backup. By default, none are excluded.

When specifying a file or directory, type either:

  • A full path name, relative to the top-level directory specified in the backup path. The path name must start with a forward slash (/). An asterisk (*) can be typed at the end as a wildcard character.
  • A terminal file or directory, which is simply the last element in the path. The name must not contain any forward slash (/) characters, but it may start or end with the wildcard character *.

For example:

ENVIRONMENT EXCLUDE “/dir1/tmp*,core,*.o”

This command excludes all files and directories that:

  • Start with the letters tmp in the directory /dir1
  • Are called core
  • End with the characters .o

The command is case-sensitive if backing up an NFS export but not if backing up a CIFS share.

EXTRACT

Possible value Notes
y or n

The default value y causes a recovery operation to extract files from a file list rather than recovering the whole backup.

FILESYSTEM

Possible value Notes
Name of directory to back up

The Storage Management Application sets the FILESYSTEM variable to the name of the path to be backed up.

FUTURE_FILES

Possible value Notes

y or n

Enables back up of files created after the start of the current backup. With NDMP version 2, the inode number that identifies a file can be reused during a backup, thereby causing the backup to fail. By default, therefore, only files created before the start of the backup are backed up. To override this behavior, set FUTURE_FILES=y.

HIST

Possible value Notes
y or n

The default value y causes file history information to be sent to the storage management application. This enables the display and recovery of the contents of a backup.

LEVEL

Possible value Notes
0 – 9, or i

The default value is 0 (full backup). If the value is set to 4, an incremental backup is taken based on the most recent previous backup of the same FILESYSTEM with level 0, 1, 2, or 3. If the value is set to i, an incremental backup is taken based on the most recent previous backup of the same FILESYSTEM of any level.

NDMP_BLUEARC_AWAIT_IDLE

Possible value Notes
y (default) or n By default, the data management engine imposes an interlock to prevent NDMP backups and accelerated data copies (ADCs) from a replication destination while a replication copy is actively writing data.

This is intended for installations that replicate to a particular volume, then back up from that same volume. However, as the lock is held at a volume level, it may be desirable in the case of directory-level replication to override this action.

To make use of this replication interlock, specify y on both the replication that is intended to do the waiting and the replication that is waited upon.

NDMP_BLUEARC_EMBEDDED_HARDLINKS

Possible value Notes
y or n Used to enable or disable inline hard linked file support. Set the value to y to enable, or n to disable. For backups, inline hard linked file support is set to n (disabled) by default, but for multi-stream operations, such as replications and accelerated data copies (ADCs) between servers, the default is overridden and inline hard linked file support is enabled. By default, replication and ADC operations use multiple data streams, so for those operations, inline hard linked file support is used by default.

When enabled, inline hard linked file support causes NDMP to back up hard linked files with both file data and file metadata inline (in a single data stream), which reduces the amount of memory the server needs to manage the data.

Set to n to disable inline hard linked file support, which causes file metadata and file data to be sent in two data streams. Disabling inline hard link file support maintains backup compatibility with older systems or releases.

Inline hard linked file support may not be enabled using the ndmp-option command. Rather, the command used to invoke NDMP must request inline hard linked file support.

Note Existing programs that can read NDMP data streams for releases prior to release 6.1 will not be able to read backups or recover from backups created using inline hard linked file support.

If a replication fails part way through, it will not be possible to restart replication if the server is downgraded to a release prior to release 6.1.

Using this option with replications and ADCs

When multi-streamed replication or ADC operations are started, this option is enabled. Starting in release 6.1, replication and ADC operations are multi-streamed by default, meaning that this option will be enabled by default for those operations.

Using backups

When backing up a file system:

  • When the embedded hard link option is enabled, the data for each hard linked file is included in the data stream wherever a path to that file is included.

    When enabled, the embedded hard link option increases the amount of data backed up, because multiple copies of the hard linked file data are included. However, it reduces the complexity of managing the backup.

    Also, note that enabling the embedded hard link option reduces the memory requirements needed to keep track of all the hard links.

  • When the embedded hard link option is disabled, paths to hard linked files are included without any data in the main part of the backup and a single copy of the hard link file data is included at the end of the backup.

    This reduces the amount of data backed up, because only a single copy of the hard linked file data is included.

Recommendations for usage with backups
  • If the backup contains many (more than a few hundred thousand) hard linked files, you should enable this option, because it reduces the memory overhead. Note that, where the backup includes many millions of hard linked files, enabling this option may allow the backup to complete where it would not complete if the option is disabled.
  • If the backup contains a relatively small number of hard linked files each containing a large amount of data, you should disable the option.
  • If there is a chance that the backup may need to be restored on an older version of software, you should disable this option.

NDMP_BLUEARC_EXCLUDE_MIGRATED

Possible value Notes
y or n

Indicates whether backups or replications will include files whose data has been migrated to secondary storage.

If set to y, the backup or copy will not include files whose data has been migrated to another volume using the Data Migrator facility.

The default n specifies that migrated files and their data will be backed up as normal files. The backup/copy retains the information that these files had originally been migrated.

NDMP_BLUEARC_EXTERNAL_LINKS

Possible value Notes
ignore, recreate_link, or remigrate Controls what happens when a replication operation encounters a cross volume link (a link to a file that has been migrated to an external server).
  • If set to ignore, the replication operation copies only the files on the primary (migrated files are not copied). Use this setting when files have been migrated because they are less useful, so they are not replicated in order to save time.
  • If set to recreate_link, the replication operation copies only the details of the cross volume link. The cross volume link is recreated on the destination if the relevant external migration data path is in place and the migrated file is accessible. Use this setting when the replication is between storage servers or clusters on the same site, and there is a single external migration target server.
    NoteDo not use the default test-before-create setting of the migration-create-links-mode CLI command if you use this option.
  • If set to remigrate, the replication operation copies the file contents but marks the file as having been externally migrated. The destination re-migrates to secondary storage if there is an existing data migration path. Use this setting when the replication is between a main site and a disaster recovery site, where the disaster recovery site includes a similar data migration configuration. This is the default.

NDMP_BLUEARC_INCLUDE_ONLY_MIGRATED

Possible value Notes
y or n

Indicates if backups or ADC copies will exclude files whose data has not been migrated to secondary storage.

If set to y, the backup or copy includes only those files whose data has been migrated to another volume using the Data Migrator facility.

The default n indicates that files whose data has not been migrated be backed up like normal files.

NDMP_BLUEARC_TAKE_SNAPSHOT

Possible value Notes
y or n

This variable is used to override the default behavior with respect to taking a file system-level snapshot during NDMP backup.

By default, HNAS server will take the file system-level snapshot during NDMP backup.

This option also applies to the file-level NDMP replication, which is configured through the File Replication Rules of the NAS Manager.

NDMP_BLUEARC_USE_CHANGE_LIST

Possible value Notes
y or n

Indicates whether incremental backups or replications will use a changed object list to direct the search for changed files; otherwise, it will have to search the entire directory tree looking for changed files. When using the changed object list, the search only passes through those directories that contain changed files.

Where a relatively small proportion of the file system includes directories containing changed files, the use of changed object lists may significantly reduce incremental backup and replication time; however, processing of the changed object list itself may take considerable time. Therefore, where file changes exist in many directories, its use is not recommended.

The default setting for this option can be set using the CLI ndmp-option change_list_incr command.

NDMP_BLUEARC_USE_SNAPSHOT_RULE

Possible value Notes

Snapshot rule name

Causes NDMP to back up the latest snapshot created under a specified snapshot rule. This can be used to backup a snapshot taken at a specific time; for example, for databases.

If set, NDMP does not create or delete snapshots.

Note Following a successful backup, the snapshot should not be deleted until after the operation has completed. In addition, the snapshot should be kept around long enough to support incremental backups.

 

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