Hi, A long time back there was a Jira raised to change the default volume choosing policy from Round Robin to Available Space:
https://issues.apache.org/jira/browse/HDFS-8538 At the time there were some objections / concerns about using available space. In the 5 years since then, at Cloudera we have seen about 1000 clusters running with Available Space enabled, and we have not seen any issues caused by it. It feels like this policy should be the default, as we have to change it more often than not. To recap, the Available Space places blocks on disks with more free space with a higher probability until all disks are within a threshold of free space from each other. After that it behaves in a round robin fashion. This means if a disk is replaced, it will slowly catch up to the usage of the others, and if you have disks of different sizes, they will self balance. I would like to ask: 1. Are there others in the community running the Available Space volume choosing policy, and if so, have you seen any issues, or does it run smoothly? 2. Does anyone have any strong objections in changing the default to Available Space from 3.4 onwards? Thanks, Stephen.
