US Robotics 7931 Podręcznik Użytkownika Pobierz pdf (Strona 103)

Chapter 3 Archiving 79

Associative Archiving: -join path

The archiver employs associative archiving if you specify the -join path

parameter. Associative archiving is useful if you want an entire directory to be

archived to one volume and you know that the archive file can physically reside on

only one volume. Otherwise, if you want to keep directories together, use either the

–sort path or -rsort path parameters to keep the files contiguous. The -rsort

parameter specifies a reverse sort.

When the archiver writes an archive file to a volume, it efficiently packs the volume

with user files. Subsequently, when accessing files from the same directory, you can

experience delays as the stage process moves through a volume to read the next file.

To alleviate delays, you can use the -join path parameter to archive files from the

same directory paths contiguously within an archive set copy. The process of

associative archiving overrides the space efficiency algorithm to archive files from

the same directory together.

Associative archiving is useful when the file content does not change but you always

want to access a group of files together. For example, you might use associative

archiving at a hospital for accessing all of the medical images associated with a

patient. For example:

Note – The -join path parameter writes data files from the same directory to the

same archive file. If there are many directories with a few small files, the archiver

creates many small archive files. These small, discrete archive files, each with its own

tar(1) header, slow the write performance of the system.

Also, because the –join path parameter specifies that all files from the same

directory be archived on a single volume, it is possible that a group of files might not

fit on any available volume. In this case, the files are not archived until more

volumes are assigned to the archive set. It is also possible that the group of files to be

archived is so large that it can never fit on a single volume. In such a case, the files

are never archived.

For most applications, using either -sort path or -join path parameter is

preferred if the more restrictive operation of -join path is not a requirement.

patient_images.1 -join path

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US Robotics 7931 Podręcznik Użytkownika Strona 103