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From "Jeremy Hanna (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-10013) Default commitlog_total_space_in_mb to 4G
Date Wed, 26 Aug 2015 14:56:46 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-10013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14713601#comment-14713601
] 

Jeremy Hanna commented on CASSANDRA-10013:
------------------------------------------

I saw that (perhaps Ryan and I are thinking of the same case) when they were doing a POC/test
cluster and used those instance types.  I would think a warning on startup and the 1/8th free
space would help in those situations.  I don't know how common it is.  I've just seen it the
one time.

Great to unify the default and the commented out value in the yaml though.

> Default commitlog_total_space_in_mb to 4G
> -----------------------------------------
>
>                 Key: CASSANDRA-10013
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10013
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Config
>            Reporter: Brandon Williams
>             Fix For: 2.1.x
>
>
> First, it bothers me that we default to 1G but have 4G commented out in the config.
> More importantly though is more than once I've seen this lead to dropped mutations, because
you have ~100 tables (which isn't that hard to do with OpsCenter and CFS and an application
that uses a moderately high but still reasonable amount of tables itself) and when the limit
is reached CLA flushes the oldest tables to try to free up CL space, but this in turn causes
a flush stampede that in some cases never ends and backs up the flush queue which then causes
the drops.  This leaves you thinking you have a load shedding situation (which I guess you
kind of do) but it would go away if you had just uncommented that config line.



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