Elasticsearch don't remove old shards

Hi. This week after _forcemerge?only_expunge_deletes=true I saw an increase in disk space usage (# 1 in the picture), after that I tried to reduce the number of replicas from 2 to 1 (# 2 in the picture), and also noticed an increase in disk space usage. After returning the number of replicas, the disk space usage also increases (# 3 in the picture).

After removed some count of replicas i expected reduce disk usage. After return count of replicas back i expected the same disk usage which was before, but usage only increase and increase.

via elasticsearch api i see that available only two shards but in data directory i see four.

Can anyone help me understand why this is occur and how to avoid it in future?

es version: 6.8.13
number of nodes: 30
number of pr shards: 20
number of replicas: 2

Welcome to our community! :smiley:

How large, in GB, is the index?

Thx. The total size of shards (with replicas) is about 100 GB.