ashutoshcipher opened a new pull request, #5044: URL: https://github.com/apache/hadoop/pull/5044
### Description of PR **Balancer shouldn't rely on "DFS Space Used %" as that ignores non-DFS used space** Report from a user here: https://groups.google.com/a/cloudera.org/d/msg/cdh-user/pIhNyDVxdVY/b7ENZmEvBjIJ (Not available now) , post archived at http://pastebin.com/eVFkk0A0 This user had a specific DN that had a large non-DFS usage among dfs.data.dirs, and very little DFS usage (which is computed against total possible capacity). Balancer apparently only looks at the usage, and ignores to consider that non-DFS usage may also be high on a DN/cluster. Hence, it thinks that if a DFS Usage report from DN is 8% only, its got a lot of free space to write more blocks, when that isn't true as shown by the case of this user. It went on scheduling writes to the DN to balance it out, but the DN simply can't accept any more blocks as a result of its disks' state. It would be better if we computed the actual utilization based on (100-(actual remaining space))/(capacity), as opposed to the current (dfs used)/(capacity). Thoughts? This isn't very critical, however, cause it is very rare to see DN space being used for non DN data, but it does expose a valid bug. ### How was this patch tested? UT ### For code changes: - [X] Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')? - [ ] Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation? - [ ] If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under [ASF 2.0](http://www.apache.org/legal/resolved.html#category-a)? - [ ] If applicable, have you updated the `LICENSE`, `LICENSE-binary`, `NOTICE-binary` files? -- 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]
