Shard Allocation Filtering

Shard allocation filtering allows you to specify which nodes are allowed to host the shards of a particular index.

It is possible to assign arbitrary metadata attributes to each node at startup. For instance, nodes could be assigned a rack and a size attribute as follows:

bin/elasticsearch -Enode.attr.rack=rack1 -Enode.attr.size=big  

These metadata attributes can be used with the index.routing.allocation.* settings to allocate an index to a particular group of nodes. For instance, we can move the index test to either big or medium nodes as follows:

PUT test/_settings
{
  "index.routing.allocation.include.size": "big,medium"
}

Alternatively, we can move the index test away from the small nodes with an exclude rule:

PUT test/_settings
{
  "index.routing.allocation.exclude.size": "small"
}

Multiple rules can be specified, in which case all conditions must be satisfied. For instance, we could move the index test to big nodes in rack1 with the following:

PUT test/_settings
{
  "index.routing.allocation.include.size": "big",
  "index.routing.allocation.include.rack": "rack1"
}

The following settings are dynamic, allowing live indices to be moved from one set of nodes to another:

These special attributes are also supported:

All attribute values can be specified with wildcards, eg:

PUT test/_settings
{
  "index.routing.allocation.include._ip": "192.168.2.*"
}