Stephen O'Donnell created HDDS-9189:
---------------------------------------
Summary: EC: Investigage how EC read path deals with unhealthy
replicas
Key: HDDS-9189
URL: https://issues.apache.org/jira/browse/HDDS-9189
Project: Apache Ozone
Issue Type: Sub-task
Reporter: Stephen O'Donnell
When SCM provides a read pipeline to a client, it simply returns a pipeline
containing all replicas it knows about. The state of a replica is not included
in the pipeline, so the client cannot distinguish between healthy and unhealthy
replicas. However the pipeline nodes are sorted, so that if there are multiple
replicas for a given replica index, and some of those nodes are not IN_SERVICE
(eg decommissioning etc), then the IN_SERVICE nodes are always sorted first.
On SCM we should be able to do something similar to put UNHEALTHY replicas to
the back of the list, so the client will try to read healthy ones first.
It is also worth checking what the client does when it encounters an unhealthy
replica - will it fall back to reconstruction read, or if there is a spare
index will it use it first?
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
