[ACCUMULO-3570] Relax restriction on instance.volumes.replacements so new volume does not have to be in instance.volumes

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.6.1
• Assignee: Christopher Tubbs
• Reporter: Christopher Tubbs
• Created: 06/Feb/15 21:43
• Updated: 11/Jun/19 04:46

Description

ACCUMULO-1832 added the ability to replace volume references with a differently named volume.

However, it also added a restriction that the new volume must be specified in the instance.volumes set. While that is a use case, it is an unnecessary restriction and conflates the purpose of replacements with regular volumes. instance.volumes is the set of volumes to write new tablets files to, while the replacements are intended to assign in remapping references to already written data, so it can be read.

One use case that this restriction prevents, for example, is migrating from failing hardware to a new cluster. A user may rename the old namenode from "nn" to "nn-old", and name the new one "nn-new", but wouldn't want new files to be written to "nn-old". This could be achieved by a custom volume chooser which blacklists "nn-old" for new tablets, but that would require writing custom code. Relaxing this restriction allows users to get the same behavior in configuration.

Issue Links

• relates to: ACCUMULO-1832 Create utility for rewriting uris