Index recovery

Peer recovery syncs data from a primary shard to a new or existing shard copy.

Peer recovery automatically occurs when Elasticsearch:

  • Recreates a shard lost during node failure
  • Relocates a shard to another node due to a cluster rebalance or changes to the shard allocation settings

You can view a list of in-progress and completed recoveries using the cat recovery API.

Peer recovery settings

indices.recovery.max_bytes_per_sec (Dynamic)

Limits total inbound and outbound recovery traffic for each node. Defaults to 40mb.

This limit applies to nodes only. If multiple nodes in a cluster perform recoveries at the same time, the cluster’s total recovery traffic may exceed this limit.

If this limit is too high, ongoing recoveries may consume an excess of bandwidth and other resources, which can destabilize the cluster.

Expert peer recovery settings

You can use the following expert setting to manage resources for peer recoveries.

indices.recovery.max_concurrent_file_chunks (Dynamic, Expert)

Number of file chunk requests sent in parallel for each recovery. Defaults to 2.

You can increase the value of this setting when the recovery of a single shard is not reaching the traffic limit set by indices.recovery.max_bytes_per_sec.