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new 1e0c7d5fe HDDS-14261. [Website v2] [Docs] [Administrator Guide]
Upgrade and Downgrade (#211)
1e0c7d5fe is described below
commit 1e0c7d5fe677eaa24cffd567c8dfbd0e272c82c4
Author: Eric C. Ho <[email protected]>
AuthorDate: Thu Jan 8 09:23:37 2026 +0800
HDDS-14261. [Website v2] [Docs] [Administrator Guide] Upgrade and Downgrade
(#211)
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+---
+sidebar_label: Upgrade and Downgrade
+---
+
# Upgrade and Downgrade
-**TODO:** File a subtask under
[HDDS-9859](https://issues.apache.org/jira/browse/HDDS-9859) and complete this
page or section.
+Ozone supports non-rolling upgrades and downgrades, where all components are
stopped first, and then restarted with the upgraded or downgraded versions.
+
+## Upgrade States
+
+After upgrading components, the upgrade process is divided into two states:
+
+1. **Pre-finalized**: When the current components are stopped and the new
versions are started, they will see that the data on disk was written by a
previous version of Ozone and enter a pre-finalized state. In the pre-finalized
state:
+ - The cluster can be downgraded at any time by stopping all components and
restarting with the old versions.
+ - Backwards incompatible features introduced in the new version will be
disallowed by the cluster.
+ - The cluster will remain fully operational with all functionality present
in the old version still allowed.
+ - Any data created while pre-finalized will remain readable after
downgrade.
+
+2. **Finalized**: When a finalize command is given to OM or SCM, they will
enter a finalized state. In the finalized state:
+ - The cluster can no longer be downgraded.
+ - All new features of the cluster introduced in the new version can be
used.
+
+### Querying finalization status
+
+**OM**: `ozone admin om finalizationstatus`. If using OM HA, finalization
status is checked for the quorum, not individual OMs.
+
+**SCM**: `ozone admin scm finalizationstatus`. SCM will report that
finalization is complete once it has finalized and is aware of enough finalized
Datanodes to form a write pipeline. The remaining Datanodes will finalize
asynchronously and be incorporated into write pipelines after informing SCM
that they have finalized.
+
+**Datanodes**: `ozone admin datanode list` will list all Datanodes and their
health state as seen by SCM. If SCM is finalized, then Datanodes whose health
state is `HEALTHY` have informed SCM that they have finalized. Datanodes whose
health state is `HEALTHY_READONLY` have not yet informed SCM that they have
finished finalization. `HEALTHY_READONLY` (pre-finalized) Datanodes remain
readable, so the cluster is operational even if some otherwise healthy
Datanodes have not yet finalized. `S [...]
+
+## Steps to upgrade and downgrade
+
+Starting with your current version of Ozone, complete the following steps to
upgrade to a newer version of Ozone.
+
+1. If using OM HA and currently running Ozone 1.2.0 or greater, prepare the
Ozone Manager. If OM HA is not being used, this step can be skipped.
+
+ ```bash
+ ozone admin om prepare -id=<om-sevice-id>
+ ```
+
+ The `prepare` command will block the Ozone Managers from receiving all
write requests. See [Ozone Manager Prepare For
Upgrade](https://ozone.apache.org/docs/edge/design/omprepare.html) for more
information
+
+2. Stop all components.
+
+3. Replace artifacts of all components with the newer versions.
+
+4. Start the components
+ 1. Start the SCM and Datanodes as usual:
+
+ ```bash
+ ozone --daemon start scm
+ ozone --daemon start datanode
+ ```
+
+ 2. Start the Ozone Manager using the `--upgrade` flag to take it out of
prepare mode.
+
+ ```bash
+ ozone --daemon start om --upgrade
+ ```
+
+ - There also exists a `--downgrade` flag which is an alias of
`--upgrade`. The name used does not matter.
+ - **IMPORTANT**: All OMs must be started with the `--upgrade` or
`--downgrade` flag in this step. If some of the OMs are not started with this
flag by mistake, run `ozone admin om cancelprepare -id=<om-sevice-id>` to make
sure all OMs leave prepare mode.
+
+ At this point, the cluster is upgraded to a pre-finalized state and fully
operational. The cluster can be downgraded by repeating the above steps, but
restoring the older versions of components in step 3, instead of the newer
versions. To finalize the cluster to use new features, continue on with the
following steps.
+
+ **Once the following steps are performed, downgrading will not be
possible.**
+
+5. Finalize SCM
+
+ ```bash
+ ozone admin scm finalizeupgrade
+ ```
+
+ At this point, SCM will tell all of the Datanodes to finalize. Once SCM
has finalized enough Datanodes to form a write pipeline, it will return that
finalization was successful. The remaining pre-finalized Datanodes will be in a
read-only state until they indicate to SCM that they have finalized. Write
requests will be directed to finalized Datanodes only.
+
+6. Finalize OM
+
+ ```bash
+ ozone admin om finalizeupgrade -id=<om-service-id>
+ ```
+
+At this point, the cluster is finalized and the upgrade is complete.
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