On Thu, 2010-04-15 at 05:37 +0000, Dietmar Maurer wrote: > > The long term goal of this work is to enable a replicated structured > > memory-based key-value storage that maintains consistency after a merge > > from a network partition. This allows IPC speed reads, and network > > speed writes of key/value pairs with full availability of key/value > > data on all nodes in the network. > > Do you plan to make that key-value store persistent? I have a glib > based implementation of such thing which uses Berkeley DB to store > data on each node (some code already posted on the openais list). > > The advantage of the 'in memory' architecture is that it is easy > to calculate diffs to do the sync (snapshots/transactions are > simply a copy in memory). The drawback is memory consumption, which > can be huge if there is a large number of key/value pairs. So > a pure database implementation (db4.7 supports snapshots and > transactions) would be even better? >
We plan to address only small scale (32 nodes or less) consistent replica hashing in memory (not persistent). Adding support for a database backend of hash key/value writes seems pretty easy to address. The properties for where this type of technology evolves into: 1) key/value store with hash-table speed lookup in majority of cases without requiring network round trip request/response operation to achieve key and value 2) scale to thousands of nodes 3) key/values are replicated, but perhaps not everywhere 4) key/values are persistently stored 5) API to access the key/value data store 6) Assume that nodes fail often and work in a nonblocking fashion when those node failures occur 7) keys can be structured, such that organization can be created identifying keys related to other keys. To achieve #2 and #6, we may need to investigate technologies alternative to corosync. The guarantees corosync provides make scaling difficult. Relaxing guarantees could allow us to scale dramatically larger for this scenario. Regards -steve _______________________________________________ Openais mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/openais
