We are having problems with our client mail server that provides imap, pop3 and smtp server.  Processes show waiting on disk but disk I/O is not busy.  It is not a hardware issue as far as I can tell because the machine is a virtual machine and other machines on the same hardware are fine.

     We are under going brute force password attacks and fail2ban is working to lock out the offending IPs but the botnet is large so there are many, over 1200 so far.

     To test the possibility that a recent software update broke something, I am restoring the machine image from a previous backup and will reboot into it shortly.