[discrete]
[[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[]
[[breaking_80_allocation_change_flood_stage_block_always_removed]]
.The automatic removal of flood-stage blocks is no longer optional.
[%collapsible]
====
*Details* +
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.

*Impact* +
Discontinue use of the `es.disk.auto_release_flood_stage_block` system property.
Specifying this property in `elasticsearch.yml` will result in an error on
startup.
====

[[breaking_80_allocation_change_include_relocations_removed]]
.Accounting for the disk usage of relocating shards is no longer optional.
[%collapsible]
====
*Details* +
By default {es} will account for the sizes of relocating shards when making
allocation decisions based on the disk usage of the nodes in the cluster. In
earlier versions the `cluster.routing.allocation.disk.include_relocations`
setting allowed this accounting to be disabled, which would result in poor
allocation decisions that might overshoot watermarks and require significant
extra work to correct. This behaviour is no longer optional, and this setting
has been removed.

*Impact* +
Discontinue use of the `cluster.routing.allocation.disk.include_relocations`
setting. Specifying this setting in `elasticsearch.yml` will result in an error
on startup.
====
// end::notable-breaking-changes[]
