[float]
[[breaking_80_allocation_changes]]
=== Allocation changes

//NOTE: The notable-breaking-changes tagged regions are re-used in the
//Installation and Upgrade Guide

//tag::notable-breaking-changes[]

// end::notable-breaking-changes[]

[float]
[[breaking_80_allocation_change_flood_stage_block_always_removed]]
==== Auto-release flood-stage block no longer optional

If a node exceeds the flood-stage disk watermark then we add a block to all of
its indices to prevent further writes as a last-ditch attempt to prevent the
node completely exhausting its disk space. By default, from 7.4 onwards the
block is automatically removed when a node drops below the high watermark
again, but this behaviour could be disabled by setting the system property
`es.disk.auto_release_flood_stage_block` to `false`. This behaviour is no
longer optional, and this system property must now not be set.