3 ms·
And what's "quorum" in a system where nodes are free to join and leave?
by acjohnson55 9y ago
And what's "quorum" in a system where nodes are free to join and leave?
- oillio 9y agoIs the answer, "a really hard problem?"
- eternalban 9y agoIt is the continuity of 'state' agreed to by a qorum of actors. The identity of these actors is irrelevant.
- bdarnell 9y agoThere's a lot of complexity here, but the short version is that nodes cannot quite come and go freely. A replica set keeps track of its members; a quorum of the existing members must vote to admit a new node, or to remove one. Note that in both CockroachDB and Spanner a cluster contains many independent and overlapping replica sets. The data is broken down into "ranges" (to use the terminology of CockroachDB; Spanner calls them "spans"), each of which has its own replica set (typically containing 3 or 5 members).