EC2 instance becomes suddenly and repeatedly unresponsive

Question

Hello all

I hae experienced some instances becoming slow and even unworkable.
Sometimes rebooting helps for a while and sometimes it does not.

In an effort to resolve this, I created a number of new instances.
Almost always they succumb to this same issue.

I tried changing the security group. I checked the load and found no high loads. Startup logs on "Get System Logs" were also fine. No issues with drive space
Serial port access through console was similarly affected, becomes suddenly unresponsive and then cannot gain access again.

SOmetimes rebooting helps and then access is possibel for some many minutes, but not hours before the instance becomes unresponsive again.

CPU credit specification is set to unlimited
The Types are mainly t3.small default Ubuntu
Region eu-west-2

I was running a small influxdb container and on some occasions also a Grafana instance in a container.

No admin issues.

Thank you for any assistance on what might be the issue. So far in responses to  similar issues, nothing strikes me as very likely. I have been using AWS for many years and have nto had such an experience before that was nto down to common and obvious usage factors.

Eric

Answer

Thank you alantam. Nie to have a quick response!!

I have it running now on the serial port:

```
 % free -h
               total        used        free      shared  buff/cache   available
Mem:           1.9Gi       389Mi       1.0Gi       2.7Mi       639Mi       1.5Gi
Swap:             0B          0B          0B
```

I cannot access it currently on the public if with ssh :shrug:
```
top - 20:07:35 up 33 min,  1 user,  load average: 0.00, 0.00, 0.00
Tasks: 107 total,   1 running, 106 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us,  0.0 sy,  0.0 ni, 95.5 id,  0.0 wa,  0.0 hi,  0.0 si,  4.5 
MiB Mem :   1910.7 total,   1040.7 free,    387.7 used,    642.5 buff/cache  
MiB Swap:      0.0 total,      0.0 free,      0.0 used.   1523.0 avail Mem

```

I cannot afford much time, so yes, I will upgrade the type just to see.
But there is something weird going on and I do not think it is related to common resources.

Strange ...

Answer

Have you checked the CPU and Memory metrics? t3.small only has 2GB RAM. I suspect the instances are running low on Memory since you mentioned reboot helps for a while.

EC2 instance becomes suddenly and repeatedly unresponsive

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