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new 5242302928 HDDS-9037. Provide documentation for Decommissioning in
Ozone (#5146)
5242302928 is described below
commit 52423029287dc56206841b9f0d16440ab8639a2b
Author: Aryan Gupta <[email protected]>
AuthorDate: Wed Aug 30 13:43:21 2023 +0530
HDDS-9037. Provide documentation for Decommissioning in Ozone (#5146)
---
hadoop-hdds/docs/content/feature/Decommission.md | 91 ++++++++++++++++++++++++
hadoop-hdds/docs/content/feature/OM-HA.md | 14 ----
2 files changed, 91 insertions(+), 14 deletions(-)
diff --git a/hadoop-hdds/docs/content/feature/Decommission.md
b/hadoop-hdds/docs/content/feature/Decommission.md
new file mode 100644
index 0000000000..bc8bc6805b
--- /dev/null
+++ b/hadoop-hdds/docs/content/feature/Decommission.md
@@ -0,0 +1,91 @@
+---
+title: "Decommissioning"
+weight: 1
+menu:
+ main:
+ parent: Features
+summary: Decommissioning of SCM, OM and Datanode.
+---
+<!---
+ 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 Decommission
+
+The DataNode decommission is the process that removes the existing DataNode
from the Ozone cluster while ensuring that the new data should not be written
to the decommissioned DataNode. When you initiate the process of
decommissioning a DataNode, Ozone automatically ensures that all the storage
containers on that DataNode have an additional copy created on another DataNode
before the decommission completes. So, datanode will keep running after it has
been decommissioned and may be used f [...]
+
+When we initiate the process of decommissioning, first we check the current
state of the node, ideally it should be "IN_SERVICE", then we change it's state
to "DECOMMISSIONING" and start the process of decommissioning, it goes through
a workflow where the following happens:
+
+1. First an event is fired to close any pipelines on the node, which will also
close any containers.
+
+2. Next the containers on the node are obtained and checked to see if new
replicas are needed. If so, the new replicas are scheduled.
+
+3. After scheduling replication, the node remains pending until replication
has completed.
+
+4. At this stage the node will complete the decommission process and the state
of the node will be changed to "DECOMMISSIONED".
+
+To check the current state of the datanodes we can execute the following
command,
+```shell
+ozone admin datanode list
+```
+
+
+To decommission a datanode you can execute the following command in cli,
+
+```shell
+ozone admin datanode decommission [-hV] [-id=<scmServiceId>]
+ [--scm=<scm>] [<hosts>...]
+```
+You can enter multiple hosts to decommission multiple datanodes together.
+
+**Note:** To recommission a datanode you may execute the below command in cli,
+```shell
+ozone admin datanode recommission [-hV] [-id=<scmServiceId>]
+ [--scm=<scm>] [<hosts>...]
+```
+
+## OM Decommission
+
+Ozone Manager (OM) decommissioning is the process in which you gracefully
remove one of the OM from the OM HA Ring.
+
+To decommission an OM and remove the node from the OM HA ring, the following
steps need to be executed.
+1. Add the _OM NodeId_ of the to be decommissioned OM node to the
_ozone.om.decommissioned.nodes.<omServiceId>_ property in _ozone-site.xml_ of
all
+ other OMs.
+2. Run the following command to decommission an OM node.
+```shell
+ozone admin om decommission -id=<om-service-id>
-nodeid=<decommissioning-om-node-id>
-hostname=<decommissioning-om-node-address> [optional --force]
+```
+The _force_option will skip checking whether OM configurations in
_ozone-site.xml_ have been updated with the decommissioned node added to
+_**ozone.om.decommissioned.nodes**_ property. <p>**Note -** It is recommended
to bootstrap another OM node before decommissioning one to maintain HA.</p>
+
+# SCM Decommission
+
+Storage Container Manager (SCM) decommissioning is the process in which you
can gracefully remove one of the SCM from the SCM HA Ring.
+
+To decommission a SCM and remove the node from the SCM HA ring, the following
steps need to be executed.
+```shell
+ozone admin scm decommission [-hV] [-id=<scmServiceId>] -nodeid=<nodeId>
+ [--scm=<scm>]
+```
+You can obtain the 'nodeId' by executing this command, **"ozone admin scm
roles"**
+
+**Note -** If you want to decommission a **primordial** scm, you may first
transfer the leadership to a non primordial scm and then decommission the
primordial scm.
+
+To transfer the leader, we can excute below command,
+```shell
+ozone admin scm transfer --service-id=scmservice -n ${nodeId}
+```
+After successful leadership change we can follow the above decommissioning
command to decommission the scm node.
diff --git a/hadoop-hdds/docs/content/feature/OM-HA.md
b/hadoop-hdds/docs/content/feature/OM-HA.md
index 1b292c78f0..3e4048c51c 100644
--- a/hadoop-hdds/docs/content/feature/OM-HA.md
+++ b/hadoop-hdds/docs/content/feature/OM-HA.md
@@ -133,20 +133,6 @@ ozone om [global options (optional)] --bootstrap --force
Note that using the _force_ option during bootstrap could crash the OM process
if it does not have updated configurations.
-## OM Decommission
-
-To decommission an OM and remove the node from the OM HA ring, the following
steps need to be executed.
-1. Stop the OzoneManager process only on the node which needs to be
decommissioned. <p> **Note -** Do not stop the decommissioning OM if there are
- only two OMs in the ring as both the OMs would be needed to reach consensus
to update the Ratis configuration.</p>
-2. Add the _OM NodeId_ of the to be decommissioned OM node to the
_ozone.om.decommissioned.nodes.<omServiceId>_ property in _ozone-site.xml_ of
all
- other OMs.
-3. Run the following command to decommission an OM node.
-```shell
-ozone admin om decommission -id=<om-service-id>
-nodeid=<decommissioning-om-node-id>
-hostname=<decommissioning-om-node-address> [optional --force]
-```
-The _force_option will skip checking whether OM configurations in
_ozone-site.xml_ have been updated with the decommissioned node added to
-_ozone.om.decommissioned.nodes_ property. <p>**Note -** It is recommended to
bootstrap another OM node before decommissioning one to maintain HA.</p>
-
## References
* Check [this page]({{< ref "design/omha.md" >}}) for the links to the
original design docs
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