Hi folks,
as I'm using venti as storage backend for an media archive, where content can be deleted (and probably will happen often enough), I'm currently thinking about how an garbage collection could be achived. Let's assume the following premise: * only a few well-known apps are writing to venti (eg. only vac and vtstore). * we know all the root scores and can iterate through the metadata from time to time. * venti's storage is divided in several logs of not to big size (eg. 2GB). Now we introduce an "deprecated" mode for an volume: no more writes to that volume, requested blocks are automatically moved to another volume (and cleared from the deprecated one). Maybe from time to time there might run an compaction process which removes the holes in the volume. Well, that's not yet any form of gc - just an smooth data moving from one volume to another - also good if you intend to take some disk offline in near future, w/o serious interruption. (The deprecated volume get emptier and emptier, and no new data is added.) GC is the next step: Assuming each block to keep is accessed at least once in some given time, we'll know that the remaining data on the volume will be trash after that time. So everything we've got to do is to iterate through all archives and access all their blocks (*1). Once this is completely done, the deferred volume only contains trash and can be safely deleted. What do you think about that approach ? cu *1) we could introduce a new "touch" rpc call, which simply tells venti that some list of blocks is still required, but does not send back their data. -- ---------------------------------------------------------------------- Enrico Weigelt, metux IT service -- http://www.metux.de/ cellphone: +49 174 7066481 email: [EMAIL PROTECTED] skype: nekrad666 ---------------------------------------------------------------------- Embedded-Linux / Portierung / Opensource-QM / Verteilte Systeme ----------------------------------------------------------------------
