Technologies/Elasticsearch/elasticsearch.node.fs.disk.free
ElasticsearchElasticsearchMetric

elasticsearch.node.fs.disk.free

Free disk space bytes
Dimensions:None
Available on:DatadogDatadog (1)DynatraceDynatrace (1)OpenTelemetryOpenTelemetry (1)

Summary

Tracks free disk space on the node's filesystem, indicating unused capacity before space exhaustion. Unlike 'available' space (which accounts for reserved space), free space shows raw unused capacity. Monitoring both free and available space helps understand true capacity constraints. Rapid decreases signal high indexing rates or insufficient retention policy enforcement, while comparing across nodes reveals imbalanced shard distribution.

Interface Metrics (3)
DatadogDatadog
The total number of unallocated bytes in the file store.
Dimensions:None
DynatraceDynatrace
Free memory in bytes
Dimensions:None
OpenTelemetryOpenTelemetry
The amount of unallocated disk space across all file stores for this node.
Dimensions:None
Sources
elasticsearch.fs.total.free_in_bytesgithub.com
elasticsearch_os_mem_free_byteswww.dynatrace.com
elasticsearch.node.fs.disk.freegithub.com
Related Insights (1)
Disk Watermark Shard Relocation Stormwarning

When any node crosses the low disk watermark (85% full by default), Elasticsearch starts relocating shards. Multiple nodes hitting watermarks simultaneously can trigger cascading relocations that overload cluster I/O and delay recovery.

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