On May 23, 2021, at around 21:57, SOL had be in technical problem. A NAS controller was broken. Controller had a redundancy. It was originally designed to failover to another controller if one unit failed, but for some reason it did not. The cause is still under investigation by the manufacturer.
After investigation of logs, on 24th at around 8:25am, we remove failed controller and reboot the system. It became fine. After that, the SOL system was restarted. At around 9:10, the SOL system was in service.
On 28th,the failed controller was replaced and it now back to normal.