What is waking my HDD up in Linux

When my disks wake up during the day, I am angry. I want silence, so I started investigating which process makes them to do that. I suspect that something is browsing Samba share, but to confirm I created this simple SystemTap script:

# cat syscall_open.stp 
#!/usr/bin/env stap
#
# System-wide strace-like tool for catching file open syscalls.
#
# Usage: stap syscall_open filename_regexp
#
probe syscall.open* {
  if (filename =~ @1) {
    printf("%s(%d) opened %s\n", execname(), pid(), filename)
  }
}

It’s as easy as starting this up and waiting until the process is found. It accepts regular expression, not a glob:

# dnf install systemtap systemtap-runtime
# stap syscall_open.stp '/mnt/int/data.*'

This will work on all SystemTap operating systems, I tested this on Fedora and any EL distribution should work too.