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From "Marcus Eriksson (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6522) DroppableTombstoneRatio JMX value is 0.0 for all CFs
Date Thu, 02 Jan 2014 10:43:52 GMT


Marcus Eriksson commented on CASSANDRA-6522:

This metric only counts deleted columns, I guess you have been doing entire row deletes?

[~jbellis] [~yukim] Should we try to estimate how many columns are affected by a row/range
tombstone and include in this metric? 

> DroppableTombstoneRatio JMX value is 0.0 for all CFs
> ----------------------------------------------------
>                 Key: CASSANDRA-6522
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Ubuntu 12.04 LTS, Cassandra 1.2.8
>            Reporter: Daniel Kador
>            Priority: Minor
> We're seeing that the JMX value for DroppableTombstoneRatio for all our CFs is 0.0. On
the face of it that seems wrong since we've definitely issued a ton of deletes for row keys
to expire some old data that we no longer need (and it definitely hasn't been reclaimed from
disk yet). Am I misunderstanding what this means / how to use it? We're on 1.2.8 and using
leveled compaction for all our CFs.
> gc_grace_seconds is set to 1 day and we've issued a series of deletes over a day ago,
so gc_grace has elapsed.
> Cluster is 18 nodes.  Two DCs, so 9 nodes in each DC.  Each node has capacity for 1.5TB
or so and is sitting with about 1TB under management.  That's why we wanted to do deletes,
obviously.  Most of that 1TB is a single CF (called "events") which represents intermediate
state for us that we can delete.
> Happy to provide any more info, just let me know.

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