When saving a station running the DataRecoveryService, the following things occur. Note this applies regardless of how the
save was issued—for example, a manually invoked command (Save Station), or an automatically issued save, e.g. a “persistent space full” condition by the DataRecoveryService, or a station save
that occurs as part of a station copy operation, reboot command, or from a “controlled shutdown” while running on backup battery
power:
- The normal station save method is used to capture all changes to all the station’s object spaces (components, alarm, history)
to flash memory, saved as the files config.bog, alarm.zip and history.zip.
- Upon a successful save, all “.drdb” files holding buffered data are erased from flash, as these are no longer necessary.
- The active SRAM data block is also cleared; however, one block operates in a “reserved state”. This is needed to capture any
changes that may occur while the station is in the “saving” state. Otherwise, data loss could potentially occur if power was
lost during or immediately after a save.
Again, note that buffered data in flash and SRAM is not erased until the save (config.bog) is successfully written to flash.
Thus, data recovery records are not lost if a power loss occurs during a save.