A rede do CentOS Server está acessível, mas o terminal não está respondendo

Question

Eu corro um servidor CentOS7x86 .

O problema a seguir acontece com tanta frequência, mas não tenho ideia de onde olhar.

1. Executar servidor
2. Executar alguns docker containers ( Jenkins , gitlab ...)
3. Parece bom, mas vários dias depois, não é possível acessar com ssh
4. Na situação de 3 , ping para o servidor parece ótimo, mas não pode acessar com ssh
5. Também no dispositivo servidor, no primeiro terminal parece bem (esperando entradas do usuário.) mas assim que o comando que eu coloquei, trava. (Por exemplo, eu tentei firewall-cmd --list-port )
6. Quando eu uso top antes, ele tem memória suficiente

Como posso resolver este problema?

• Posso supor que seja apenas um problema de rede, já que posso acessar com ping ?
• É possível apenas a porta 22 bloqueada?

Preciso de algum conselho sobre como começar esse tipo de problema. Obrigado.

EDITAR =======================

sar relatórios de comando como seguir

[ice@ice ~]$ sar
Linux 3.10.0-123.el7.x86_64 (DCSF-DEV08)    08/03/2017  _x86_64_    (24 CPU)

12:00:01 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
12:10:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
12:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
12:30:01 AM     all      2.74      0.00      1.61      0.02      0.00     95.62
12:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
12:50:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
01:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
01:10:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
01:20:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
01:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
01:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
01:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
02:00:02 AM     all      2.74      0.00      1.62      0.02      0.00     95.63
02:10:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.63
02:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
02:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
02:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.63
02:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
03:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
03:10:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
03:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
03:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
03:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
03:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
04:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
04:10:01 AM     all      2.74      0.00      1.63      0.02      0.00     95.62
04:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
04:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
04:40:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
04:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
05:00:02 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
05:10:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
05:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
05:30:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
05:40:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
05:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
06:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
06:10:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
06:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
06:30:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
06:40:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
06:50:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
07:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
07:10:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
07:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
07:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
07:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
07:50:02 AM     all      2.74      0.00      1.62      0.02      0.00     95.63
08:00:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62

08:00:01 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
08:10:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
08:20:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.62
08:30:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
08:40:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
08:50:01 AM     all      2.74      0.00      1.61      0.02      0.00     95.63
09:00:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
09:10:01 AM     all      2.74      0.00      1.61      0.02      0.00     95.63
09:20:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
09:30:01 AM     all      2.75      0.00      1.61      0.02      0.00     95.63
09:40:01 AM     all      2.74      0.00      1.61      0.02      0.00     95.62
09:50:01 AM     all      2.74      0.00      1.62      0.02      0.00     95.62
10:00:01 AM     all      2.79      0.00      1.64      0.02      0.00     95.55
10:10:01 AM     all      2.75      0.00      1.62      0.02      0.00     95.62
Average:        all      2.74      0.00      1.62      0.02      0.00     95.62

Para mim, como idle é mais de 90%, o problema de memória não deveria ter acontecido.

FYI, minha configuração de troca é ( sysctl -a | grep swappiness ):

vm.swappiness = 60