[3/3] kudu git commit: [docs] Add a bit of information about tombstoned replicas

[mp...@apache.org]

[docs] Add a bit of information about tombstoned replicas

This adds a quick paragraph to the troubleshooting docs about tombstoned
replicas. I've seen quite a few users be alarmed by tombstones and
believe they need to be dealt with somehow, possibly by deletion. Of
course, this is dangerous, and having docs to point people towards will
be nice, and may prevent some user consternation.

Change-Id: I876aeb1ffeb7251fe36fe6022b722ed88997cdbe
Reviewed-on: http://gerrit.cloudera.org:8080/10372
Tested-by: Will Berkeley <wd...@gmail.com>
Reviewed-by: Mike Percy <mp...@apache.org>


Project: http://git-wip-us.apache.org/repos/asf/kudu/repo
Commit: http://git-wip-us.apache.org/repos/asf/kudu/commit/05d59486
Tree: http://git-wip-us.apache.org/repos/asf/kudu/tree/05d59486
Diff: http://git-wip-us.apache.org/repos/asf/kudu/diff/05d59486

Branch: refs/heads/master
Commit: 05d594867c6a442691274b9b9a402b804eca1516
Parents: ba0a812
Author: Will Berkeley <wd...@apache.org>
Authored: Fri May 11 00:58:57 2018 -0700
Committer: Mike Percy <mp...@apache.org>
Committed: Fri May 11 23:25:27 2018 +0000

----------------------------------------------------------------------
 docs/troubleshooting.adoc | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/kudu/blob/05d59486/docs/troubleshooting.adoc
----------------------------------------------------------------------
diff --git a/docs/troubleshooting.adoc b/docs/troubleshooting.adoc
index edb8991..826b2b8 100644
--- a/docs/troubleshooting.adoc
+++ b/docs/troubleshooting.adoc
@@ -602,3 +602,19 @@ link:http://kudu.apache.org/releases/[releases page] has links to documentation
 for previous versions of Kudu; for the latest release, see the
 link:known_issues.html[known issues page].
 
+[[tombstoned_or_stopped_tablets]]
+=== Tombstoned or STOPPED tablet replicas
+
+Users may notice some replicas on a tablet server are in a STOPPED state, and
+remain on the server indefinitely. These replicas are tombstones. A tombstone
+indicates that the tablet server once held a bona fide replica of its tablet.
+For example, if a tablet server goes down and its replicas are re-replicated
+elsewhere, if the tablet server rejoins the cluster its replicas will become
+tombstones. A tombstone will remain until the table it belongs to is deleted, or
+a new replica of the same tablet is placed on the tablet server. A count of
+tombstoned replicas and details of each one are available on the /tablets page
+of the tablet server web UI.
+
+The Raft consensus algorithm that Kudu uses for replication requires tombstones
+for correctness in certain rare situations. They consume minimal resources and
+hold no data. They must not be deleted.