On last Sunday (March 1, 2020), the main SSD of this server was completely FAILED. There was no chance to recover, the backup disk was also FAILED BEYOND REPAIR.
I already replaced the failed disks with a new one (without backup disk yet), and then rebuilt everything from scratch.
In short; we lost everything.
I'm really sorry for the lost of your blogs and contents. I will create a better backup/recovery plan for sure.