[jira] [Resolved] (CASSANDRA-7034) commitlog files are 32MB in size, even with a 64bit OS and jvm

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

     [ https://issues.apache.org/jira/browse/CASSANDRA-7034?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benedict resolved CASSANDRA-7034.
---------------------------------

    Resolution: Invalid

The parameter you are referring to is the *total* space for the commit log to use, not the per-segment file size. This defaults to 32Mb.

Note the total is only a best effort also: if the total is exceeded writes are not blocked; an attempt is only made to flush the column families that are retaining the entries in the commit log, so that they may be reclaimed, however the space cannot be reclaimed until this completes.

> commitlog files are 32MB in size, even with a 64bit  OS and jvm
> ---------------------------------------------------------------
>
>                 Key: CASSANDRA-7034
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7034
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Donald Smith
>
> We did a rpm install of cassandra 2.0.6 on CentOS 6.4 running 
> {noformat}
> > java -version
> Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
> Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)
> {noformat}
> That is the version of java CassandraDaemon is using.
> We used the default setting (None) in cassandra.yaml for commitlog_total_space_in_mb:
> {noformat}
> # Total space to use for commitlogs.  Since commitlog segments are
> # mmapped, and hence use up address space, the default size is 32
> # on 32-bit JVMs, and 1024 on 64-bit JVMs.
> #
> # If space gets above this value (it will round up to the next nearest
> # segment multiple), Cassandra will flush every dirty CF in the oldest
> # segment and remove it.  So a small total commitlog space will tend
> # to cause more flush activity on less-active columnfamilies.
> # commitlog_total_space_in_mb: 4096
> {noformat}
> But our commitlog files are 32MB in size, not 1024MB.
> OpsCenter confirms that commitlog_total_space_in_mb is None.
> I don't think the problem is in cassandra-env.sh, because when I run it manually and echo the  values of the version variables I get:
> {noformat}
> jvmver=1.7.0_40
> JVM_VERSION=1.7.0
> JVM_ARCH=64-Bit
> {noformat}



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