On 2017-03-12 10:44 (-0700), Anuj Wadehra <anujw_2...@yahoo.co.in> wrote: > Hi, > > Our setup is as follows: > 2 DCS with N nodes, RF=DC1:3,DC2:3, Hinted Handoff=3 hours, Incremental > Repair scheduled once on every node (ALL DCs) within the gc grace period. > > I have following queries regarding incremental repairs: > > 1. When a node is down for X hours (where x > hinted handoff hours and less > than gc grace time), I think incremental repair is sufficient rather than > doing the full repair. Is the understanding correct ? >
Incremental repair SHOULD provide the same guarantees as regular repair. > 2. DataStax recommends "Run incremental repair daily, run full repairs weekly > to monthly". Does that mean that I have to run full repairs every week to > month EVEN IF I do daily incremental repairs? If yes, whats the reasoning of > running full repair when inc repair is already run? > > Reference: > https://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsRepairNodesWhen.html > I don't know why datastax suggests this, there are some nasty edge cases when you mix incremental repair and full repair ( https://issues.apache.org/jira/browse/CASSANDRA-13153 ) > 3. We run inc repair at least once in gc grace instead of the general > recommendation that inc repair should be run daily. Do you see any problem > with the approach? > > The more often you run it, the less data will be transferred, and the less painful it will be. By running it weekly, you're making each run do 7x as much as work compared to running it daily, increasing the chance of having it impact your typical latencies.
