Error logs and comportaments strange in server

Hello i have this in error log php

[28-Feb-2020 01:16:18] WARNING: [pool www] child 17061 said into stderr: “mysqldump: Got error: 2005: “Unknown MySQL server host ‘global-db:3306’ (-2)” when trying to connect”
[28-Feb-2020 01:18:37] WARNING: [pool www] child 17299 said into stderr: “mysqldump: Got error: 2005: “Unknown MySQL server host ‘global-db:3306’ (-2)” when trying to connect”
[28-Feb-2020 01:30:14] WARNING: [pool www] child 17364 said into stderr: “mysqldump: Got error: 2005: “Unknown MySQL server host ‘global-db:3306’ (-2)” when trying to connect”

My site fail of nothing is strange. And Back. I see that he fail the cause is full disk. But today fail again. The coincidence that is run snapshot and server fail after back of nothing. And not have nothing in logs. I see of nginx of php too. Your have a few idea?