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Posted to commits@cassandra.apache.org by "Jon Haddad (JIRA)" <ji...@apache.org> on 2015/02/26 18:41:04 UTC

[jira] [Created] (CASSANDRA-8868) JBOD Aware Size Tiered Compaction Strategy

Jon Haddad created CASSANDRA-8868:
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             Summary: JBOD Aware Size Tiered Compaction Strategy
                 Key: CASSANDRA-8868
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8868
             Project: Cassandra
          Issue Type: New Feature
          Components: Core
            Reporter: Jon Haddad
            Priority: Minor
         Attachments: jbod_aware.png

I'd like to propose a new compaction strategy targeting JBOD configurations.  I believe this strategy would be most useful to machines with 4+ spinning disks but would also see some benefit on SSDs.

There are a several goals with this strategy: 

1. Minimize disk seeks during the compaction process
2. Maximize disk throughput when multiple disks are present
3. Better data distribution across disks.  Data should automatically be balanced (applies when adding a new, empty disk)

When a compaction is to occur, the algorithm first selects a disk to be the receiver.  This disk should be the one with the most free space.  The fullest disks are chosen to be the origin.  SStables are selected from the origin disks, and compacted onto the receiver.  This should both minimize seeks as well as auto balance.  

I'm not sure if this would apply to leveled compaction, but it may apply to date tiered.



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