On Mon, May 15, 2017 at 10:35 PM, Venkateswara Rao Jujjuri < jujj...@gmail.com> wrote:
> As we are moving towards mega store, which can house 10s of millions(even > 100s) of ledgers, and 1000s of bookies, there can be a huge overhead on > some of the operations we are performing right now. > > 1. Compaction/GC > A deletion is just a metadata operation. Deletes the zk node. (currently it > just deletes the leaf node, which can be a minor bugfix to delete entire > tree if applicable). +1 for a fix for improving this. > But each bookie > need to get a list of existing ledgers from bookie, compare to its local > storage, and identify > deleted ledgers. Then go through compaction logic which is another process. > > But 1000s of bookies, in parallel parsing the entire zk tree, making their > own list doesn't appear to be efficient scalable architecture to me. > > Why not introduce a opportunistic delete operation from client side, which > will inform to all bookies in that ledger's metadata. We can still keep our > bruit-force method but at very very low frequency, once a week? to address > transient/corner case scenarios like bookie down at that time etc. Is there > any big architectural correctness issue I am missing in this method? > I don't think there is a correctness issue for the approach your proposed if current background gc is still running. The current approach is just for simplifying the client logic. Instead of introducing complexity (more operations) on client side, why can't the leader (auditor) perform the deletions? > > 2. Close > Ledger close is also a metadata operation. I believe sending opportunistic > close to bookies of the current ensemble can greatly enhance some of the > use-cases where we need open-to-close consistency. Where in the data > doesn't need to be persistent until the close. Any thoughts?? > You mean "close-to-open" consistency? I am trying to understand - Why "where in the data doesn't need to be persistent until the close" is related to ledger close? Are you thinking of flushing all entries on the bookies on closing a ledger? How do you handle ensemble changes? - Sijie > > -- > Jvrao > --- > First they ignore you, then they laugh at you, then they fight you, then > you win. - Mahatma Gandhi >
