What happened, all mysql databases under wordpress on the server were cleaned up?

Question

linux

The server was under centos.
Fail2ban seems to be set up.
php.ini disable_functions = show_source,system,shell_exec,passthru,exec,phpinfo,popen,proc_open,eval
vestcp panel.
One user per domain.
Today all databases are empty.... most sites, users.
WTF?!
According to the mysqld.log logs,
there is a lot of this for all or almost all domains

151210  9:45:51 [ERROR] /usr/libexec/mysqld: Can't open file: './user_1/wp_options.frm' (errno: 24)
151210  9:45:57 [ERROR] /usr/libexec/mysqld: Can't open file: './user_2/70q83c_options.frm' (errno: 24)

151210 17:47:56 [Note] Event Scheduler: Purging the queue. 0 events
151210 17:47:56  InnoDB: Starting shutdown...
151210 17:47:57  InnoDB: Shutdown completed; log sequence number 710936729
151210 17:47:57 [Note] /usr/libexec/mysqld: Shutdown complete

Answer 1

1) Contact support
2) Restore backup

Answer 2

They say here that the 24th error means that it simply cannot open files, the limit has been exceeded.
try in my.cnf
[mysqld]
open_files_limit = 100000
and restart the muscle