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https://issues.apache.org/jira/browse/CASSANDRA-19715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17855952#comment-17855952
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Michael Semb Wever edited comment on CASSANDRA-19715 at 6/18/24 2:23 PM:
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bq. So, with compaction_window_entropy and compaction_window_entropy_unit, we
can ensure that compactions don't happen on all the nodes at the same time?
Given an entropy large enough compared to the compaction time taken, probably
nodes would not overlap. This goes back to the yaml or sys prop suggestion, in
avoiding the randomness tactic.
Something like {{`-Dcassandra.twcs_compaction_delay_seconds=900`}}
(you'd stagger the delay manually on each node, accordingly)
was (Author: michaelsembwever):
bq. So, with compaction_window_entropy and compaction_window_entropy_unit, we
can ensure that compactions don't happen on all the nodes at the same time?
Given an entropy large enough compared to the compaction time taken, probably
nodes would not overlap. This goes back to the yaml or sys prop suggestion, in
avoiding the randomness tactic.
Something like {{`-Dcassandra.twcs_compaction_delay_seconds=900`}}
> TWCS - Provide a flag to pick a time when compaction happens for the n-1
> window
> -------------------------------------------------------------------------------
>
> Key: CASSANDRA-19715
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19715
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Venkata Naladala
> Priority: Normal
>
> Below are the settings for the TWCS. With the settings below, the compaction
> for the n-1 window happens at around 00:00 UTC on all the nodes in the
> cluster. This causes a spike in IO utilization on the entire cluster, which
> in turn increases the read latencies.
> {{{}compaction = { 'class' :
> 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy',
> 'compaction_window_size' : 1, 'compaction_window_unit' : 'DAYS',
> 'max_threshold' : 32, 'min_threshold' : 4{}}}}
> Requesting to provide a new option for TWCS where we can specify when the
> compaction for n-1 window happens. This way, we can provide a custom time
> instead of the default time(beginning of the new window) so that we can pick
> low-traffic hours and avoid impacting the customer.
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