70 lines
2.8 KiB
Plaintext
70 lines
2.8 KiB
Plaintext
|
[[disk-allocator]]
|
||
|
|
=== Disk-based Shard Allocation
|
||
|
|
|
||
|
|
Elasticsearch factors in the available disk space on a node before deciding
|
||
|
|
whether to allocate new shards to that node or to actively relocate shards
|
||
|
|
away from that node.
|
||
|
|
|
||
|
|
Below are the settings that can be configred in the `elasticsearch.yml` config
|
||
|
|
file or updated dynamically on a live cluster with the
|
||
|
|
<<cluster-update-settings,cluster-update-settings>> API:
|
||
|
|
|
||
|
|
`cluster.routing.allocation.disk.threshold_enabled`::
|
||
|
|
|
||
|
|
Defaults to `true`. Set to `false` to disable the disk allocation decider.
|
||
|
|
|
||
|
|
`cluster.routing.allocation.disk.watermark.low`::
|
||
|
|
|
||
|
|
Controls the low watermark for disk usage. It defaults to 85%, meaning ES will
|
||
|
|
not allocate new shards to nodes once they have more than 85% disk used. It
|
||
|
|
can also be set to an absolute byte value (like 500mb) to prevent ES from
|
||
|
|
allocating shards if less than the configured amount of space is available.
|
||
|
|
|
||
|
|
`cluster.routing.allocation.disk.watermark.high`::
|
||
|
|
|
||
|
|
Controls the high watermark. It defaults to 90%, meaning ES will attempt to
|
||
|
|
relocate shards to another node if the node disk usage rises above 90%. It can
|
||
|
|
also be set to an absolute byte value (similar to the low watermark) to
|
||
|
|
relocate shards once less than the configured amount of space is available on
|
||
|
|
the node.
|
||
|
|
|
||
|
|
NOTE: Percentage values refer to used disk space, while byte values refer to
|
||
|
|
free disk space. This can be confusing, since it flips the meaning of high and
|
||
|
|
low. For example, it makes sense to set the low watermark to 10gb and the high
|
||
|
|
watermark to 5gb, but not the other way around.
|
||
|
|
|
||
|
|
|
||
|
|
`cluster.info.update.interval`::
|
||
|
|
|
||
|
|
How often Elasticsearch should check on disk usage for each node in the
|
||
|
|
cluster. Defaults to `30s`.
|
||
|
|
|
||
|
|
`cluster.routing.allocation.disk.include_relocations`::
|
||
|
|
|
||
|
|
Defaults to +true+, which means that Elasticsearch will take into account
|
||
|
|
shards that are currently being relocated to the target node when computing a
|
||
|
|
node's disk usage. Taking relocating shards' sizes into account may, however,
|
||
|
|
mean that the disk usage for a node is incorrectly estimated on the high side,
|
||
|
|
since the relocation could be 90% complete and a recently retrieved disk usage
|
||
|
|
would include the total size of the relocating shard as well as the space
|
||
|
|
already used by the running relocation.
|
||
|
|
|
||
|
|
|
||
|
|
An example of updating the low watermark to no more than 80% of the disk size, a
|
||
|
|
high watermark of at least 50 gigabytes free, and updating the information about
|
||
|
|
the cluster every minute:
|
||
|
|
|
||
|
|
[source,js]
|
||
|
|
--------------------------------------------------
|
||
|
|
PUT /_cluster/settings
|
||
|
|
{
|
||
|
|
"transient": {
|
||
|
|
"cluster.routing.allocation.disk.watermark.low": "80%",
|
||
|
|
"cluster.routing.allocation.disk.watermark.high": "50gb",
|
||
|
|
"cluster.info.update.interval": "1m"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
--------------------------------------------------
|
||
|
|
// AUTOSENSE
|
||
|
|
|