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amitosh avatar image
amitosh asked ·

how we can achieve and test commit log compression

Hi Team ,

I am trying commit log compression for dse 5.1.16,

how we can achieve and test commit log compression.

Thanks

commit log compression
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Aleks Volochnev avatar image
Aleks Volochnev answered ·

Hi Amitosh,

the default commit log location is `/var/lib/cassandra/commitlog`, in your case it may be configured to be different. After changing the settings (commitlog_compression) and restarting the database, you may check the difference there.

Compression settings for the commit log are documented here: https://docs.datastax.com/en/dse/5.1/dse-admin/datastax_enterprise/config/configCassandra_yaml.html#configCassandra_yaml__PerformanceTuningProps

Normal commit log is uncompressed, so it looks like that:

Notice that commit log compression may lead to a bit higher CPU load, I'd not set the compression level to be too high.

You could try to enable commit log compression on a single node and then compare it with the regular 'unchanged' node next to it.


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Erick Ramirez avatar image
Erick Ramirez answered ·

@amitosh In the cassandra.yaml, enable commitlog compression with:

commitlog_compression:
  - class_name: LZ4Compressor

Your results may vary depending on your cluster's access patterns and the type of disk being used for the commit log. Cheers!

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