jojochuang commented on code in PR #8728: URL: https://github.com/apache/ozone/pull/8728#discussion_r2198705296
########## hadoop-hdds/docs/content/feature/Maintenance.md: ########## @@ -0,0 +1,78 @@ +--- +title: "Maintenance Mode" +menu: + main: + parent: Features +summary: Maintenance mode for Datanodes. +--- +<!--- + Licensed to the Apache Software Foundation (ASF) under one or more + contributor license agreements. See the NOTICE file distributed with + this work for additional information regarding copyright ownership. + The ASF licenses this file to You under the Apache License, Version 2.0 + (the "License"); you may not use this file except in compliance with + the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +--> + +# DataNode Maintenance Mode + +Maintenance mode is a feature in Apache Ozone that allows you to temporarily take a DataNode offline for maintenance operations (e.g., hardware upgrades, software updates) without triggering immediate data replication. Unlike decommissioning, which aims to permanently remove a DataNode and its data from the cluster, maintenance mode is designed for temporary outages. + +While in maintenance mode, a DataNode does not accept new writes but may still serve reads, assuming containers are healthy and online. Existing data on the DataNode will remain in place, and replication of its data will only be triggered if the DataNode remains in maintenance mode beyond a configurable timeout period. This allows for planned downtime without unnecessary data movement, reducing network overhead and cluster load. + +The DataNode transitions through the following operational states during maintenance: + +1. **IN_SERVICE**: The DataNode is fully operational and participating in data writes and reads. +2. **ENTERING_MAINTENANCE**: The DataNode is transitioning into maintenance mode. New writes will be avoided. +3. **IN_MAINTENANCE**: The DataNode is in maintenance mode. Data will not be written to it. If the DataNode remains in this state beyond the configured maintenance window, its data will start to be replicated to other DataNodes to ensure data durability. + +## Command Line Usage + +To place a DataNode into maintenance mode, use the `ozone admin datanode maintenance` command. You can specify a duration for the maintenance period. If no duration is specified, a default duration will be used (this can be configured). Review Comment: Default is indefinitely. See line 53. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
