What would it take to put in a journaling filesystem? On Fri, Jul 11, 2008 at 10:49 AM, Eben Eliason <[EMAIL PROTECTED]> wrote: > 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 >
-- Edward Cherlin End Poverty at a Profit by teaching children business http://www.EarthTreasury.org/ "The best way to predict the future is to invent it."--Alan Kay _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel