Split Extension
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## Split Extension

The Split Extension is a Cedar Backup extension used to split up large files within staging directories. It is probably only useful in combination with the cback3-span command, which requires individual files within staging directories to each be smaller than a single disc.

You would normally run this action immediately after the standard stage action, but you could also choose to run it by hand immediately before running cback3-span.

The split extension uses the standard UNIX split tool to split the large files up. This tool simply splits the files on bite-size boundaries. It has no knowledge of file formats.

Note: this means that in order to recover the data in your original large file, you must have every file that the original file was split into. Think carefully about whether this is what you want. It doesn't sound like a huge limitation. However, cback3-span might put an indivdual file on any disc in a set — the files split from one larger file will not necessarily be together. That means you will probably need every disc in your backup set in order to recover any data from the backup set.

To enable this extension, add the following section to the Cedar Backup configuration file:

    <extensions>
       <action>
          <name>split</name>
          <module>CedarBackup3.extend.split</module>
          <function>executeAction</function>
          <index>299</index>
       </action>
    </extensions>

This extension relies on the options and staging configuration sections in the standard Cedar Backup configuration file, and then also requires its own `split` configuration section. This is an example Split configuration section:

    <split>
       <size_limit>250 MB</size_limit>
       <split_size>100 MB</split_size>
    </split>

The following elements are part of the Split configuration section:

`size_limit`

  Size limit.

  Files with a size strictly larger than this limit will be split by the extension.

  You can enter this value in two different forms. It can either be a simple number, in which case the value is assumed to be in bytes; or it can be a number followed by a unit (KB, MB, GB).

  Valid examples are “10240”, “250 MB” or “1.1 GB”.

  Restrictions: Must be a size as described above.

`split_size`

  Split size.

  This is the size of the chunks that a large file will be split into. The final chunk may be smaller if the split size doesn't divide evenly into the file size.

  You can enter this value in two different forms. It can either be a simple number, in which case the value is assumed to be in bytes; or it can be a number followed by a unit (KB, MB, GB).

  Valid examples are “10240”, “250 MB” or “1.1 GB”.

  Restrictions: Must be a size as described above.

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