Disk space usage, missing free space

Hi, I am using ELK 8.3 , 3 servers. 2 storage servers and one for cluster.
Initially I've got one server, when I've run out of free space I've added another one server for storage and third, because you need 3 servers (elk, elk2, elk3) for cluster. Now I'am running out of space on both server and I can't understand what's happening, please help.

I see that all shards are on 2nd server

GET /_cat/shards?v&bytes=gb
net-2024.11.12 0 p STARTED 162287087    13      13 192.168.18.221 elk2
net-2024.11.12 0 r UNASSIGNED                                     
net-2024.05.21 0 p STARTED 168674245    14      14 192.168.18.221 elk2
net-2024.05.21 0 r UNASSIGNED                           
net-2024.03.20 0 p STARTED 157339574    13      13 192.168.18.221 elk2
net-2024.05.04 0 p STARTED 165000099    14      14 192.168.18.221 elk2
net-2024.09.24 0 p STARTED 155278336    13      13 192.168.18.221 elk2
net-2024.09.24 0 r UNASSIGNED                    
.slo-observability.summary-v2 0 p STARTED 0 0 0 192.168.18.221 elk2

But there is no space on both servers

GET /_cat/nodes?v&h=name,ip,disk.used_percent,disk.total,disk.used
name ip          disk.used_percent disk.total disk.used
elk3 192.168.18.220             15.37     36.1gb     5.5gb
elk2 192.168.18.221             92.35      8.1tb     7.4tb
elk  192.168.18.222             96.14      3.4tb     3.3tb

all segments are one the 2nd server


GET /_cat/segments?v&bytes=gb

net-2024.05.10 0 p 192.168.18.221 _0 0 38757  0  0 0 true  true 9.8.0   true
net-2024.05.10 0 p 192.168.18.221 _1 1 28487  0  0 0 true  true 9.8.0   true
net-2024.05.10 0 p 192.168.18.221 _2 2 41548  0  0 0 true  true 9.8.0   true
net-2024.05.10 0 p 192.168.18.221 _3 3 53654  0  0 0 true  true 9.8.0   true
net-2024.05.10 0 p 192.168.18.221 _4 4 44436  0  0 0 true  true 9.8.0   true

There is two question:

  1. How find what is filling up space on first server an free it up (it's not a logs, I've checked)
  2. How to make Elastic to use both server to store data ? I just want to split data e.g. 1,3,5 shards on 1st server and 2,4,6 shards on 2nd server