Shard Allocation Filtering
editShard Allocation Filtering
editWhile Index Shard Allocation provides per-index settings to control the allocation of shards to nodes, cluster-level shard allocation filtering allows you to allow or disallow the allocation of shards from any index to particular nodes.
The available dynamic cluster settings are as follows, where {attribute}
refers to an arbitrary node attribute.:
-
cluster.routing.allocation.include.{attribute} -
Allocate shards to a node whose
{attribute}has at least one of the comma-separated values. -
cluster.routing.allocation.require.{attribute} -
Only allocate shards to a node whose
{attribute}has all of the comma-separated values. -
cluster.routing.allocation.exclude.{attribute} -
Do not allocate shards to a node whose
{attribute}has any of the comma-separated values.
These special attributes are also supported:
|
|
Match nodes by node names |
|
|
Match nodes by IP addresses (the IP address associated with the hostname) |
|
|
Match nodes by hostnames |
The typical use case for cluster-wide shard allocation filtering is when you want to decommission a node, and you would like to move the shards from that node to other nodes in the cluster before shutting it down.
For instance, we could decommission a node using its IP address as follows:
PUT _cluster/settings
{
"transient" : {
"cluster.routing.allocation.exclude._ip" : "10.0.0.1"
}
}
Shards will only be relocated if it is possible to do so without breaking another routing constraint, such as never allocating a primary and replica shard to the same node.
In addition to listing multiple values as a comma-separated list, all attribute values can be specified with wildcards, eg:
PUT _cluster/settings
{
"transient": {
"cluster.routing.allocation.exclude._ip": "192.168.2.*"
}
}