[ https://issues.apache.org/jira/browse/HADOOP-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Steve Loughran resolved HADOOP-8047. ------------------------------------ Resolution: Won't Fix > CachedDNSToSwitchMapping caches negative results forever > -------------------------------------------------------- > > Key: HADOOP-8047 > URL: https://issues.apache.org/jira/browse/HADOOP-8047 > Project: Hadoop Common > Issue Type: Bug > Components: util > Affects Versions: 1.0.0, 0.23.0, 0.24.0 > Reporter: Steve Loughran > Priority: Trivial > > This is very minor, just worth filing in JIRA unless someone wants to rethink > topology caching for a dynamic world. > # The CachedDNSToSwitchMapping caches the results from all relayed DNS > queries. > # The DNS script mapper returns the default rack for all unknown entries (or > when the script fails) > # The Cache stores this in its map and never re-resolves it. > As a result, if a node is added to a live cluster that the existing script > cannot resolve, then it won't get assigned to a rack unless the script is > updated before the rack map is resolved. > This isn't usually that important, it just means "update your scripts before > adding new racks". Perhaps there should be a page on that activity, "runbook > and checklist for adding new servers and racks". > Where it would matter if anyone started playing with dynamic topologies, but > in that situation the cached mapping itself would become the liability, as it > assumes that servers never switch switches in a live system: the topology is > static for existing nodes. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-dev-h...@hadoop.apache.org