Data Domain: An explanation of 'filesys fastcopy force' and 'filesys fastcopy update' commands available on a Data Domain Restorer (DDR)

Resumen: This article describes the functionality offered by the optional force/update arguments which can be provided to the 'filesys fastcopy' command

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Instrucciones

The Data Domain Operating System (DDOS) contains 'fastcopy' functionality which can be used to clone files on a Data Domain Restorer (DDR) to an alternate location within the local instance of the Data Domain File System (DDFS). For example:
 
# filesys fastcopy source [source directory tree or file] destination [destination directory tree or file]

Note that this functionality works by:
  • Creating a brand new file/set of files at the location given as the destination
  • Cloning the metadata of existing files at the location given as the source to the new files at the destination
As a result:
  • Fastcopy of each file is extremely quick (as the operation only involves manipulation of file metadata and no physical backup data is read/written to disk) - it is much faster than using an external client to read source files/write destination files
  • Files created by fastcopy will de-duplicate perfectly against existing data on disk (as they will reference the exact same physical data as source files) - due to this compression statistics for the files may show inflated ratios
When fastcopying directory trees (or entire mtrees) if the destination directory (or mtree) already exists the destinations current content will be removed and replaced by the results of the fastcopy command. In addition if fastcopying a single file and the destination file already exists the destination file will be removed and replaced by the result of the fastcopy command. In these scenarios (i.e. where there is a possibility that existing destination data will be lost) the fastcopy command will:
  • Prompt for confirmation that the copy should be performed
  • Create a point in time snapshot of the destination mtree before modifying its contents - this snapshot can then be used to recover deleted/overwritten files if the command was run in error
For example - fastcopying a single file when the destination file already exists:
 
# filesys fastcopy source /data/col1/backup/testfile destination /data/col1/backup/testfile_new
Destination "/data/col1/backup/testfile_new" already exists.
Proceeding will overwrite its content with "/data/col1/backup/testfile".
    Are you sure? (yes|no) [no]: yes
ok, proceeding.
Creating snapshot "FASTCOPY-2017-05-08-04-57-47" with one-hour retention period...done
Use this snapshot to recover in case of a mistake.
Fastcopy status: fastcopy /data/col1/backup/testfile to /data/col1/backup/testfile_new: no changes in 0.00 seconds

Fastcopying an entire mtree when the destination mtree already exists:
 
# filesys fastcopy source /data/col1/backup destination /data/col1/new_mtree
Destination "/data/col1/new_mtree" already exists.
Proceeding will overwrite its content with "/data/col1/backup".
    Are you sure? (yes|no) [no]: yes
ok, proceeding.
Creating snapshot "FASTCOPY-2017-05-08-04-58-34" with one-hour retention period...done
Use this snapshot to recover in case of a mistake.
(00:00) Waiting for fastcopy to complete...
Fastcopy status: fastcopy /data/col1/backup to /data/col1/new_mtree: copied 3 files in 0.02 seconds

Using the 'force' argument:
 
# filesys fastcopy force source [source directory tree or file] destination [destination directory tree or file]

Use of the optional force argument avoids the following when data already exists at the fastcopy destination:
  • The user being prompted for confirmation
  • Creation of a point in time snapshot of the destination mtree
For example:
 
# filesys fastcopy force source /data/col1/backup/testfile destination /data/col1/backup/testfile_new
Fastcopy status: fastcopy /data/col1/backup/testfile to /data/col1/backup/testfile_new: no changes in 0.00 seconds

# filesys fastcopy force source /data/col1/backup destination /data/col1/new_mtree
Fastcopy status: fastcopy /data/col1/backup to /data/col1/new_mtree: no changes in 0.01 seconds

This can be advantageous when running 'filesys fastcopy' commands in a non interactive manner (for example from scripts) however should be used carefully as if an incorrect fastcopy command is run any destination data which is removed cannot be recovered.

Using the 'update' argument:
 
# filesys fastcopy update source [source directory tree or file] destination [destination directory tree or file]
 
Use of the optional update argument prevents data which exists in a destination directory/mtree from being removed by a fastcopy. For example source and destination directories exist and contain files as shown below:
 
# ls /data/col1/backup/sourcedir
sourcefile1  sourcefile2  sourcefile3
# ls /data/col1/backup/destdir
destfile1  destfile2  destfile3

If a fastcopy is performed without the update argument the contents of the destination directory will be removed and replaced with that from the source, i.e.:
 
# filesys fastcopy source /data/col1/backup/sourcedir destination /data/col1/backup/destdir
...
Fastcopy status: fastcopy /data/col1/backup/sourcedir to /data/col1/backup/destdir: deleted 3 files; copied 3 files in 0.01 seconds
 
# ls /data/col1/backup/destdir
sourcefile1  sourcefile2  sourcefile3

If, however, the update argument is used then the contents of the source directory will be added to the destination directory and existing files in the destination directory will not be removed, i.e.:
 
# ls /data/col1/backup/destdir
destfile1  destfile2  destfile3

# filesys fastcopy update source /data/col1/backup/sourcedir destination /data/col1/backup/destdir
Fastcopy status: fastcopy /data/col1/backup/sourcedir to /data/col1/backup/destdir: copied 3 files in 0.00 seconds

# ls /data/col1/backup/destdir
destfile1  destfile2  destfile3  sourcefile1  sourcefile2  sourcefile3

Note, however, that if there is an existing file in the destination directory with the same name as a file in the source directory fastcopy will overwrite the destination file with contents from the source even with the update argument (and the user will not be prompted that this is taking place).

Información adicional

The force and update arguments are mutually exclusive and cannot be given together in a single 'filesys fastcopy' command.

Productos afectados

Data Domain

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Data Domain
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Número del artículo: 000022663
Tipo de artículo: How To
Última modificación: 08 set. 2025
Versión:  5
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