[jira] [Created] (ACCUMULO-4078) Exclude special volumes

["Matt Peterson (JIRA)" <ji...@apache.org>]

Matt Peterson created ACCUMULO-4078:
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             Summary: Exclude special volumes
                 Key: ACCUMULO-4078
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4078
             Project: Accumulo
          Issue Type: Improvement
          Components: core
    Affects Versions: 1.7.0
            Reporter: Matt Peterson
            Priority: Minor


A few improvements to the VolumeChooser are desired for a particular use case that seems to be general enough that it warrants an updated to Accumulo.  Perhaps these ideas should become sub-tickets.  Note that the improvements listed below have been implemented for my particular instance and I expect to submit them as a patch.

Use Case:
A new volume is added, with limited capacity, to be dedicated for a specific table.  All other tables or files should be excluded from this new volume.

Suggested Improvements:
1. Update the signature for VolumeManager.choose to take a VolumeChooserEnvironment instead of Optional<String>.  This will allow future parameters for volume selection without repeatedly changing the VolumeManager interface.

2. It's not currently possible to specify preferred volumes for the write-ahead logs

3. In several places including PreferredVolumeChooser, PerTableVolumeChooser and VolumeManagerImpl, the failsafe chooser is the RandomVolumeChooser which will include the instance volume that needs to be excluded.  It would be useful to have a configurable failsafe in this situation.

4. The volume chooser is called in FileUtils for temp directory creation but it could instead use the sticky dir to create the temp directory, not needing the volume chooser at all.



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