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https://issues.apache.org/jira/browse/CASSANDRA-17150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17515870#comment-17515870
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Andres de la Peña commented on CASSANDRA-17150:
-----------------------------------------------
The proposed patch is based on an old patch by [~jasonstack] , with some
additions by [~eduard.tudenhoefner]:
||PR||CI||
|[trunk|https://github.com/apache/cassandra/pull/1546]|[j8|https://app.circleci.com/pipelines/github/adelapena/cassandra/1462/workflows/4ab5ec86-29c3-4f87-bd7b-8918b6ab3315]
[j11|https://app.circleci.com/pipelines/github/adelapena/cassandra/1462/workflows/88b87a3f-25eb-4f04-aceb-df194fb29bc4]|
It adds a new guardrail for warning or failing write queries when the disk
usage of the targeted replicas is over the thresholds defined in config. The
calculation of disk usage includes the size of memtables that are about to be
flushed, and the guardrail doesn't affect non-CQL writes, such as streamed
sstables.
Each node runs a periodic task that calculates the local disk usage and whether
it's over the threshold limits. This determines the state of the node, which
can be {{{}NOT_AVAILABLE{}}}, {{{}SPACIOUS{}}}, {{STUFFED}} or {{{}FULL{}}}.
This state, if changed, is propagated to the other nodes through a new
{{{}ApplicationState.DISK_USAGE{}}}. When those states arrive to the other
nodes, they cache them so every node has a map of endpoints to disk usage
states. That map is used by coordinator nodes to evaluate if the replicas
targeted by a write are spacious enough.
> Guardrails for disk usage
> -------------------------
>
> Key: CASSANDRA-17150
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17150
> Project: Cassandra
> Issue Type: New Feature
> Components: Feature/Guardrails
> Reporter: Andres de la Peña
> Assignee: Andres de la Peña
> Priority: Normal
> Fix For: 4.x
>
>
> Add guardrails for disk usage establishing soft/hard limits on the percentage
> of used disk space. For example:
> {code}
> # Warning threshold to warn when local disk usage exceeds threshold. Valid
> values: (1, 100]
> # Defaults to -1 to disable.
> # disk_usage_percentage_warn_threshold: -1
> # Failure threshold to reject write requests if replica disk usage exceeds
> threshold. Valid values: (1, 100]
> # Defaults to -1 to disable.
> # disk_usage_percentage_failure_threshold: -1
> {code}
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