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new 2e6c7b81a HDDS-14318. [Website v2] [Docs] [System Internals] Datanode
Schema v3 (#228)
2e6c7b81a is described below
commit 2e6c7b81a6ecb5f04210d30518a2f9537e875477
Author: Bolin Lin <[email protected]>
AuthorDate: Fri Jan 9 02:28:01 2026 -0500
HDDS-14318. [Website v2] [Docs] [System Internals] Datanode Schema v3 (#228)
---
cspell.yaml | 1 +
.../01-components/03-datanode/02-rocksdb-schema.md | 52 ++++++++++++++++++++--
2 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/cspell.yaml b/cspell.yaml
index b249fb7ac..e02f3feab 100644
--- a/cspell.yaml
+++ b/cspell.yaml
@@ -77,6 +77,7 @@ words:
- SCM
- datanode
- datanodes
+- DN
- ofs
- FSO
- OBS
diff --git
a/docs/07-system-internals/01-components/03-datanode/02-rocksdb-schema.md
b/docs/07-system-internals/01-components/03-datanode/02-rocksdb-schema.md
index a21812534..34689b827 100644
--- a/docs/07-system-internals/01-components/03-datanode/02-rocksdb-schema.md
+++ b/docs/07-system-internals/01-components/03-datanode/02-rocksdb-schema.md
@@ -1,7 +1,53 @@
---
-sidebar_label: RocksDB Layout
+sidebar_label: Datanode Container Schema v3
---
-# Datanode RocksDB Schema
+# Datanode Container Schema v3
-**TODO:** File a subtask under
[HDDS-9862](https://issues.apache.org/jira/browse/HDDS-9862) and complete this
page or section.
+In Ozone, user data are separated into blocks and stored in HDDS Containers.
Containers are the fundamental replication unit of Ozone/HDDS. Each Container
has its metadata and data. Data are saved as files on disk. Metadata is saved
in RocksDB.
+
+Earlier, there was one RocksDB for each Container on Datanode. With user data
continuously growing, there will be hundreds of thousands of RocksDB instances
on one Datanode. It's a big challenge to manage this amount of RocksDB
instances in one JVM.
+
+Unlike the previous approach, Container Schema v3 uses only one RocksDB for
each data volume, holding all metadata of Containers in this RocksDB.
+
+## Configuration
+
+This is mainly a Datanode feature, which doesn't require much configuration.
By default, it is enabled.
+
+Here is a configuration which disables this feature if the "one RocksDB for
each container" mode is more preferred. Please be noted that once the feature
is enabled, it's strongly suggested not to disable it later.
+
+```xml
+<property>
+ <name>hdds.datanode.container.schema.v3.enabled</name>
+ <value>false</value>
+ <description>Disable or enable this feature.</description>
+</property>
+```
+
+Without any specific configuration, the single RocksDB will be created under
the data volume configured in `hdds.datanode.dir`.
+
+For some advanced cluster admins who have the high performance requirement,
they can leverage quick storages to save RocksDB. In this case, configure these
two properties:
+
+```xml
+<property>
+ <name>hdds.datanode.container.db.dir</name>
+ <value/>
+ <description>This setting is optional. Specify where the per-disk RocksDB
instances will be stored.</description>
+</property>
+
+<property>
+ <name>hdds.datanode.failed.db.volumes.tolerated</name>
+ <value>-1</value>
+ <description>The number of db volumes that are allowed to fail before a
Datanode stops offering service.
+ Default -1 means unlimited, but we should have at least one good volume
left.</description>
+</property>
+```
+
+## Backward Compatibility
+
+Existing containers each has one RocksDB for them will be still accessible
after this feature is enabled. All container data will co-exist in an existing
Ozone cluster.
+
+## References
+
+- Design doc: [HDDS-3630 Merge Container RocksDB in
DN](https://ozone.apache.org/docs/edge/design/dn-merge-rocksdb.html)
+- Jira: [HDDS-3630](https://issues.apache.org/jira/browse/HDDS-3630)
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