I was fixing a non-booting server, i soon found the problem.
A drive in a RAID array was making a high-pitched whining sound.
The Seagate (ST2000DM001) drive failed and caused all the problems.
The drive was out of warranty so I opened the drive:
A few months later i was confronted with another failed drive in the server.
The drive is from the same manufacturer and the same model (ST2000DM001).
See the pictures of the opened drive:
To prevent another Head Crash I replaced all the drives for WD drives (WD2000FYYZ).
Will the last Seagate ST2000DM001 drive fail? I am counting on it.