OpenSearch/docs/reference/cat/shards.asciidoc

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[[cat-shards]]
== Shards
The `shards` command is the detailed view of what nodes contain which
shards. It will tell you if it's a primary or replica, the number of
docs, the bytes it takes on disk, and the node where it's located.
Here we see a single index, with three primary shards and no replicas:
[source,shell]
--------------------------------------------------
% curl 192.168.56.20:9200/_cat/shards
wiki1 0 p STARTED 3014 31.1mb 192.168.56.10 Stiletto
wiki1 1 p STARTED 3013 29.6mb 192.168.56.30 Frankie Raye
wiki1 2 p STARTED 3973 38.1mb 192.168.56.20 Commander Kraken
--------------------------------------------------
[[index-pattern]]
=== Index pattern
If you have many shards, you may wish to limit which indices show up
in the output. You can always do this with `grep`, but you can save
some bandwidth by supplying an index pattern to the end.
[source,shell]
--------------------------------------------------
% curl 192.168.56.20:9200/_cat/shards/wiki2
wiki2 0 p STARTED 197 3.2mb 192.168.56.10 Stiletto
wiki2 1 p STARTED 205 5.9mb 192.168.56.30 Frankie Raye
wiki2 2 p STARTED 275 7.8mb 192.168.56.20 Commander Kraken
--------------------------------------------------
[[relocation]]
=== Relocation
Let's say you've checked your health and you see two relocating
shards. Where are they from and where are they going?
[source,shell]
--------------------------------------------------
% curl 192.168.56.10:9200/_cat/health
1384315316 20:01:56 foo green 3 3 12 6 2 0 0
% curl 192.168.56.10:9200/_cat/shards | fgrep RELO
wiki1 0 r RELOCATING 3014 31.1mb 192.168.56.20 Commander Kraken -> 192.168.56.30 Frankie Raye
wiki1 1 r RELOCATING 3013 29.6mb 192.168.56.10 Stiletto -> 192.168.56.30 Frankie Raye
--------------------------------------------------
[[states]]
=== Shard states
Before a shard can be used, it goes through an `INITIALIZING` state.
`shards` can show you which ones.
[source,shell]
--------------------------------------------------
% curl -XPUT 192.168.56.20:9200/_settings -d'{"number_of_replicas":1}'
{"ok":true,"acknowledged":true}
% curl 192.168.56.20:9200/_cat/shards
wiki1 0 p STARTED 3014 31.1mb 192.168.56.10 Stiletto
wiki1 0 r INITIALIZING 0 14.3mb 192.168.56.30 Frankie Raye
wiki1 1 p STARTED 3013 29.6mb 192.168.56.30 Frankie Raye
wiki1 1 r INITIALIZING 0 13.1mb 192.168.56.20 Commander Kraken
wiki1 2 r INITIALIZING 0 14mb 192.168.56.10 Stiletto
wiki1 2 p STARTED 3973 38.1mb 192.168.56.20 Commander Kraken
--------------------------------------------------
If a shard cannot be assigned, for example you've overallocated the
number of replicas for the number of nodes in the cluster, they will
remain `UNASSIGNED`.
[source,shell]
--------------------------------------------------
% curl -XPUT 192.168.56.20:9200/_settings -d'{"number_of_replicas":3}'
% curl 192.168.56.20:9200/_cat/health
1384316325 20:18:45 foo yellow 3 3 9 3 0 0 3
% curl 192.168.56.20:9200/_cat/shards
wiki1 0 p STARTED 3014 31.1mb 192.168.56.10 Stiletto
wiki1 0 r STARTED 3014 31.1mb 192.168.56.30 Frankie Raye
wiki1 0 r STARTED 3014 31.1mb 192.168.56.20 Commander Kraken
wiki1 0 r UNASSIGNED
wiki1 1 r STARTED 3013 29.6mb 192.168.56.10 Stiletto
wiki1 1 p STARTED 3013 29.6mb 192.168.56.30 Frankie Raye
wiki1 1 r STARTED 3013 29.6mb 192.168.56.20 Commander Kraken
wiki1 1 r UNASSIGNED
wiki1 2 r STARTED 3973 38.1mb 192.168.56.10 Stiletto
wiki1 2 r STARTED 3973 38.1mb 192.168.56.30 Frankie Raye
wiki1 2 p STARTED 3973 38.1mb 192.168.56.20 Commander Kraken
wiki1 2 r UNASSIGNED
--------------------------------------------------