We have recently upgraded our cluster to ES 8.12.2. We are observing unassigned shards and on further looking cluster allocation explain API we could see that can_allocate="yes" and allocate_explanation "Elasticsearch can allocate the shard."
It has set of available nodes which it can allocate to but it is not able to move replica shards to them.
+1 I am also facing same issues
At a guess, try setting cluster.routing.allocation.allow_rebalance: always. This will be the default from 8.16 onwards, see Always allow rebalancing by default by DaveCTurner · Pull Request #111015 · elastic/elasticsearch · GitHub.
Even after cluster.routing.allocation.allow_rebalance: always setting, shards gets unassigned and on cluster allocation explain it says can_allocate="yes" and allocate_explanation "Elasticsearch can allocate the shard."
Could you share the full output of GET _cluster/allocation/explain and GET _internal/desired_balance?
not able to paste the full output, is there any location where I can paste?
https://gist.github.com is usually a good choice.
pls check if you can access https://github.com/mukularora89-dev/ES8_Issue
I cannot access that, it says Page not found.
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