Index recovery settings
editIndex recovery settings
editPeer 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.
Recovery settings
edit-
indices.recovery.max_bytes_per_sec
-
(Dynamic) Limits total inbound and outbound recovery traffic for each node. Applies to both peer recoveries as well as snapshot recoveries (i.e., restores from a snapshot). Defaults to
40mb
unless the node is a dedicated cold or frozen node, in which case the default relates to the total memory available to the node:Total memory Default recovery rate on cold and frozen nodes ≤ 4 GB
40 MB/s
> 4 GB and ≤ 8 GB
60 MB/s
> 8 GB and ≤ 16 GB
90 MB/s
> 16 GB and ≤ 32 GB
125 MB/s
> 32 GB
250 MB/s
This limit applies to each node separately. 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.
This is a dynamic setting, which means you can set it in each node’s
elasticsearch.yml
config file and you can update it dynamically using the cluster update settings API. If you set it dynamically then the same limit applies on every node in the cluster. If you do not set it dynamically then you can set a different limit on each node, which is useful if some of your nodes have better bandwidth than others. For example, if you are using Index Lifecycle Management then you may be able to give your hot nodes a higher recovery bandwidth limit than your warm nodes.
Expert peer recovery settings
editYou can use the following expert setting to manage resources for peer recoveries.
-
indices.recovery.max_concurrent_file_chunks
-
(Dynamic, Expert) Number of file chunks 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
, up to a maximum of8
. -
indices.recovery.max_concurrent_operations
-
(Dynamic, Expert) Number of operations sent in parallel for each recovery. Defaults to
1
.Concurrently replaying operations during recovery can be very resource-intensive and may interfere with indexing, search, and other activities in your cluster. Do not increase this setting without carefully verifying that your cluster has the resources available to handle the extra load that will result.
-
indices.recovery.use_snapshots
-
(Dynamic, Expert) Enables snapshot-based peer recoveries.
Elasticsearch recovers replicas and relocates primary shards using the peer recovery process, which involves constructing a new copy of a shard on the target node. When
indices.recovery.use_snapshots
isfalse
Elasticsearch will construct this new copy by transferring the index data from the current primary. When this setting istrue
Elasticsearch will attempt to copy the index data from a recent snapshot first, and will only copy data from the primary if it cannot identify a suitable snapshot. Defaults totrue
.Setting this option to
true
reduces your operating costs if your cluster runs in an environment where the node-to-node data transfer costs are higher than the costs of recovering data from a snapshot. It also reduces the amount of work that the primary must do during a recovery.Additionally, repositories having the setting
use_for_peer_recovery=true
will be consulted to find a good snapshot when recovering a shard. If none of the registered repositories have this setting defined, index files will be recovered from the source node. -
indices.recovery.max_concurrent_snapshot_file_downloads
-
(Dynamic, Expert) Number of snapshot file downloads requests sent in parallel to the target node for each recovery. Defaults to
5
.Do not increase this setting without carefully verifying that your cluster has the resources available to handle the extra load that will result.
-
indices.recovery.max_concurrent_snapshot_file_downloads_per_node
-
(Dynamic, Expert) Number of snapshot file downloads requests executed in parallel in the target node for all recoveries. Defaults to
25
.Do not increase this setting without carefully verifying that your cluster has the resources available to handle the extra load that will result.
Recovery settings for managed services
editThis feature is designed for indirect use by Elasticsearch Service, Elastic Cloud Enterprise, and Elastic Cloud on Kubernetes. Direct use is not supported.
When running Elasticsearch as a managed service, the following settings allow the service to specify absolute maximum bandwidths for disk reads, disk writes, and network traffic on each node, and permit you to control the maximum recovery bandwidth on each node in terms of these absolute maximum values. They have two effects:
-
They determine the bandwidth used for recovery if
indices.recovery.max_bytes_per_sec
is not set, overriding the default behaviour described above. -
They impose a node-wide limit on recovery bandwidth which is independent of
the value of
indices.recovery.max_bytes_per_sec
.
If you do not set indices.recovery.max_bytes_per_sec
then the maximum
recovery bandwidth is computed as a proportion of the absolute maximum
bandwidth. The computation is performed separately for read and write traffic.
The service defines the absolute maximum bandwidths for disk reads, disk
writes, and network transfers using node.bandwidth.recovery.disk.read
,
node.bandwidth.recovery.disk.write
and node.bandwidth.recovery.network
respectively, and you can set the proportion of the absolute maximum bandwidth
that may be used for recoveries by adjusting
node.bandwidth.recovery.factor.read
and
node.bandwidth.recovery.factor.write
. If the operator privileges feature is enabled
then the service may also set default proportions using operator-only variants
of these settings.
If you set indices.recovery.max_bytes_per_sec
then Elasticsearch will use its value
for the maximum recovery bandwidth, as long as this does not exceed the
node-wide limit. Elasticsearch computes the node-wide limit by multiplying the absolute
maximum bandwidths by the
node.bandwidth.recovery.operator.factor.max_overcommit
factor. If you set
indices.recovery.max_bytes_per_sec
in excess of the node-wide limit then the
node-wide limit takes precedence.
The service should determine values for the absolute maximum bandwidths settings by experiment, using a recovery-like workload in which there are several concurrent workers each processing files sequentially in chunks of 512kiB.
-
node.bandwidth.recovery.disk.read
-
(byte value per second) The absolute maximum disk read speed for
a recovery-like workload on the node. If set,
node.bandwidth.recovery.disk.write
andnode.bandwidth.recovery.network
must also be set. -
node.bandwidth.recovery.disk.write
-
(byte value per second) The absolute maximum disk write speed
for a recovery-like workload on the node. If set,
node.bandwidth.recovery.disk.read
andnode.bandwidth.recovery.network
must also be set. -
node.bandwidth.recovery.network
-
(byte value per second) The absolute maximum network throughput
for a recovery-like workload on the node, which applies to both reads and
writes. If set,
node.bandwidth.recovery.disk.read
andnode.bandwidth.recovery.disk.write
must also be set. -
node.bandwidth.recovery.factor.read
-
(float, dynamic) The proportion of the maximum read
bandwidth that may be used for recoveries if
indices.recovery.max_bytes_per_sec
is not set. Must be greater than0
and not greater than1
. If not set, the value ofnode.bandwidth.recovery.operator.factor.read
is used. If no factor settings are set then the value0.4
is used. -
node.bandwidth.recovery.factor.write
-
(float, dynamic) The proportion of the maximum
write bandwidth that may be used for recoveries if
indices.recovery.max_bytes_per_sec
is not set. Must be greater than0
and not greater than1
. If not set, the value ofnode.bandwidth.recovery.operator.factor.write
is used. If no factor settings are set then the value0.4
is used. -
node.bandwidth.recovery.operator.factor.read
-
(float, dynamic) The proportion of the maximum read
bandwidth that may be used for recoveries if
indices.recovery.max_bytes_per_sec
andnode.bandwidth.recovery.factor.read
are not set. Must be greater than0
and not greater than1
. If not set, the value ofnode.bandwidth.recovery.operator.factor
is used. If no factor settings are set then the value0.4
is used. When the operator privileges feature is enabled, this setting can be updated only by operator users. -
node.bandwidth.recovery.operator.factor.write
-
(float, dynamic) The proportion of the maximum
write bandwidth that may be used for recoveries if
indices.recovery.max_bytes_per_sec
andnode.bandwidth.recovery.factor.write
are not set. Must be greater than0
and not greater than1
. If not set, the value ofnode.bandwidth.recovery.operator.factor
is used. If no factor settings are set then the value0.4
is used. When the operator privileges feature is enabled, this setting can be updated only by operator users. -
node.bandwidth.recovery.operator.factor
-
(float, dynamic) The proportion of the maximum
bandwidth that may be used for recoveries if neither
indices.recovery.max_bytes_per_sec
nor any other factor settings are set. Must be greater than0
and not greater than1
. Defaults to0.4
. When the operator privileges feature is enabled, this setting can be updated only by operator users. -
node.bandwidth.recovery.operator.factor.max_overcommit
-
(float, dynamic) The proportion of the absolute
maximum bandwidth that may be used for recoveries regardless of any other
settings. Must be greater than
0
. Defaults to100
. When the operator privileges feature is enabled, this setting can be updated only by operator users.