CedarBackup2.actions.store

Package CedarBackup2 :: Package actions :: Module store

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Module CedarBackup2.actions.store

Implements the standard 'store' action.

Author: Kenneth J. Pronovici <pronovic@ieee.org>

Function Summary
	`executeStore(configPath, options, config)` Executes the store backup action.
	`createWriter(config)` Creates a writer object based on current configuration.
	`writeImage(config, newDisc, stagingDirs)` Builds and writes an ISO image containing the indicated stage directories.
	`writeStoreIndicator(config, stagingDirs)` Writes a store indicator file into staging directories.
	`consistencyCheck(config, stagingDirs)` Runs a consistency check against media in the backup device.

Variable Summary
`Logger`	`logger` = `<logging.Logger instance at 0x402e76ec>`

Function Details

executeStore(configPath, options, config)

Executes the store backup action.

Parameters:: configPath - Path to configuration file on disk.
(type=String representing a path on disk.); options - Program command-line options.
(type=Options object.); config - Program configuration.
(type=Config object.)

Raises:: ValueError - Under many generic error conditions; IOError - If there are problems reading or writing files.

Notes:

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.
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.

createWriter(config)

Creates a writer object based on current configuration.

This function creates and returns a writer based on configuration. This is done to abstract action functionality from knowing what kind of writer is in use. Since all writers implement the same interface, there's no need for actions to care which one they're working with.

Currently, the cdwriter and dvdwriter device types are allowed. An exception will be raised if any other device type is used.

This function also checks to make sure that the device isn't mounted before creating a writer object for it. Experience shows that sometimes if the device is mounted, we have problems with the backup. We may as well do the check here first, before instantiating the writer.

Parameters:: config - Config object.

Returns:: Writer that can be used to write a directory to some media.

Raises:: ValueError - If there is a problem getting the writer.; IOError - If there is a problem creating the writer object.

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.

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.

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.

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.

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.

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

Variable Details

logger

Type:: Logger
Value:: <logging.Logger instance at 0x402e76ec>

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