[CASSANDRA-16602] Revise the metrics docs in the website

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-rc1, 4.0
• Component/s: Legacy/Documentation and Website
• Bug Category: Documentation
• Severity: Normal
• Complexity: Low Hanging Fruit
• Discovered By: User Report
• Platform: All
• Since Version: 4.0-alpha1

Source Control Link

https://github.com/apache/cassandra/commit/0fd8f0a52fbd69c47d073373abfe7d2437bbd9ca

Test and Documentation Plan

build the docs and inspect

• Assignee: Yifan Cai
• Reporter: Yifan Cai

Authors

Yifan Cai

Reviewers

Brandon Williams

• Created: 14/Apr/21 18:57
• Updated: 16/Mar/22 15:39
• Resolved: 21/Apr/21 20:26

Description

While inspecting the metrics code, I realized that the metrics docs (at https://cassandra.apache.org/doc/latest/operating/metrics.html) has several errors, e.g.

1. JMX MBean names have incorrect format. They should be separated with commas, but the doc has space separated values. Cassandra users referring to this docs will not get it working.
2. The MBean name for Keyspace metrics is wrong. In the code, we have `keyspace=<Keyspace>`, instead of `scope=<Keyspace>`, which is listed in the docs page.
3. There are outdated fields. For instance, the `SyncTime` has been renamed to `RepairSyncTime` under the TableMetrics.

To avoid frustrating and confusing the users that refer to the metrics page, the docs need to be revised.