On Fri, Jul 11, 2008 at 1:33 PM, Gary C Martin <[EMAIL PROTECTED]> wrote: > One concern I have with auto saving state before powering off is the > potential corruption of journal data. How robust is the Journal if > power off happens half way through an ongoing auto state save – do you > loose both the new journal entry and the original entry you had > resumed from (partially overwritten)?
Disclaimer: I'm not a technical expert on the DS, so others more familiar should probably correct me if I make claims below that are false. This is yet another problem that can be bypassed with the "new DS". In one of our past meetings, we laid out requirements for the process by which activities save their state, and it included a means for activities to check in temporary saves if they wished to, optionally passing a flag to tell the Journal to actually create a new entry. This system was in place such that, if the Journal detected that a given activity crashed, it could automatically make a new Journal entry based on the last temporary save, as a form of auto-recovery. This approach could similarly be used after a power failure. Additionally, in the worst case a corrupt entry might wind up in the Journal, but that shouldn't be a problem because, at present, copies are stored so there is no loss of data, and in the future we'll have versions, and only one version of many would be corrupt. It should never be the case that the entry that was opened gets corrupted. Ideally the Journal would be able to recognize when a save transaction doesn't finish and either replace it with the most recent temporary state or remove the entry compeletely. - Eben _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel