CedarBackup3.actions.store

Implements the standard ‘store’ action. :author: Kenneth J. Pronovici <pronovic@ieee.org> :author: Dmitry Rutsky <rutsky@inbox.ru>

Module Contents

CedarBackup3.actions.store.logger
CedarBackup3.actions.store.executeStore(configPath, options, config)

Executes the store backup action.

Note: The rebuild action and the store action are very similar. The main difference is that while store only stores a single day’s staging directory, the rebuild action operates on multiple staging directories.

Note: When the store action is complete, we will write a store indicator to the daily staging directory we used, so it’s obvious that the store action has completed.

Parameters

  • configPath (String representing a path on disk) – Path to configuration file on disk

  • options (Options object) – Program command-line options

  • config (Config object) – Program configuration

Raises

  • ValueError – Under many generic error conditions

  • IOError – If there are problems reading or writing files

CedarBackup3.actions.store.writeImage(config, newDisc, stagingDirs)

Builds and writes an ISO image containing the indicated stage directories.

The generated image will contain each of the staging directories listed in stagingDirs. The directories will be placed into the image at the root by date, so staging directory /opt/stage/2005/02/10 will be placed into the disc at /2005/02/10.

Note: This function is implemented in terms of writeImageBlankSafe. The newDisc flag is passed in for both rebuildMedia and todayIsStart.

Parameters

  • config – Config object

  • newDisc – Indicates whether the disc should be re-initialized

  • stagingDirs – Dictionary mapping directory path to date suffix

Raises

  • ValueError – Under many generic error conditions

  • IOError – If there is a problem writing the image to disc

CedarBackup3.actions.store.writeImageBlankSafe(config, rebuildMedia, todayIsStart, blankBehavior, stagingDirs)

Builds and writes an ISO image containing the indicated stage directories.

The generated image will contain each of the staging directories listed in stagingDirs. The directories will be placed into the image at the root by date, so staging directory /opt/stage/2005/02/10 will be placed into the disc at /2005/02/10. The media will always be written with a media label specific to Cedar Backup.

This function is similar to writeImage, but tries to implement a smarter blanking strategy.

First, the media is always blanked if the rebuildMedia flag is true. Then, if rebuildMedia is false, blanking behavior and todayIsStart come into effect:

If no blanking behavior is specified, and it is the start of the week,
the disc will be blanked

If blanking behavior is specified, and either the blank mode is "daily"
or the blank mode is "weekly" and it is the start of the week, then
the disc will be blanked if it looks like the weekly backup will not
fit onto the media.

Otherwise, the disc will not be blanked

How do we decide whether the weekly backup will fit onto the media? That is what the blanking factor is used for. The following formula is used:

will backup fit? = (bytes available / (1 + bytes required) <= blankFactor

The blanking factor will vary from setup to setup, and will probably require some experimentation to get it right.

Parameters

  • config – Config object

  • rebuildMedia – Indicates whether media should be rebuilt

  • todayIsStart – Indicates whether today is the starting day of the week

  • blankBehavior – Blank behavior from configuration, or None to use default behavior

  • stagingDirs – Dictionary mapping directory path to date suffix

Raises

  • ValueError – Under many generic error conditions

  • IOError – If there is a problem writing the image to disc

CedarBackup3.actions.store.writeStoreIndicator(config, stagingDirs)

Writes a store indicator file into staging directories.

The store indicator is written into each of the staging directories when either a store or rebuild action has written the staging directory to disc.

Parameters

  • config – Config object

  • stagingDirs – Dictionary mapping directory path to date suffix

CedarBackup3.actions.store.consistencyCheck(config, stagingDirs)

Runs a consistency check against media in the backup device.

It seems that sometimes, it’s possible to create a corrupted multisession disc (i.e. one that cannot be read) although no errors were encountered while writing the disc. This consistency check makes sure that the data read from disc matches the data that was used to create the disc.

The function mounts the device at a temporary mount point in the working directory, and then compares the indicated staging directories in the staging directory and on the media. The comparison is done via functionality in filesystem.py.

If no exceptions are thrown, there were no problems with the consistency check. A positive confirmation of “no problems” is also written to the log with info priority.

@warning: The implementation of this function is very UNIX-specific.

Parameters

  • config – Config object

  • stagingDirs – Dictionary mapping directory path to date suffix

Raises

  • ValueError – If the two directories are not equivalent

  • IOError – If there is a problem working with the media