US Robotics 7931 Podręcznik Użytkownika Pobierz pdf (Strona 174)

150 Sun StorageTek SAM Archive Configuration and Administration Guide • Version 4, Update 6, 04/07

The capacity of a volume is the total amount of space for data on a volume. For

example, a 10-gigabyte tape volume with 3 gigabytes written to it has a capacity of

10 gigabytes and 7 gigabytes of free space.

New or newly labeled archive media starts out with all its capacity as free space. As

data is archived to the media, the amount of free space decreases and the amount of

current data increases.

As archived files in the file system are changed or removed, their archive images

expire and they move from the current data classification to the expired data

classification. The physical space used by these images remains the same; there is

simply no longer a file in the file system pointing to that space. Only when space is

recycled can these images be removed and the space they occupy become free. The

goal of the recycler is to transform space used by expired data into free space

without losing any current data.

The recycler and the archiver work together, as follows:

1. The recycler marks all the current (valid) archive images that are present on a

volume with the rearchive attribute.

2. If you are archiving to removable media, the recycler marks the selected archive

volume with the recycle attribute. This prevents the archiver from writing any

more archive images to the volume.

3. The archiver moves all the marked images to another volume. This operation is

called rearchiving. After the archiver moves the current archive images from the

old volume to the new volume, the old volume contains only free space and

expired space. If you are archiving to removable media cartridges, you can relabel

and reuse the cartridge. If you are archiving to disk, the recycler removes the file

that contains the expired archive images.

The recycler is designed to run periodically. It performs as much work as it can each

time it is invoked. The recycler has to finish marking copies for rearchiving before

the archiver can rearchive the files.

Sometimes expired archive images, with the rearchive attribute set, remain on

media. This can happen under the following conditions:

■ The archiver does not run after the recycler marks expired archive images.

■ Media is not available for the archiver to use when moving the unexpired archive

images.

■ There are miscellaneous archiver anomalies.

Between executions, the recycler keeps state information in the library catalogs and

the inodes. During the recycling process, you can use the sls(1) command and its

-D option to display information about a file. The output from the sls(1) command

shows whether or not a file is scheduled for rearchiving.

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US Robotics 7931 Podręcznik Użytkownika Strona 174