Unmounted/unpartitioned HDD wakes up ~4 times per day on CentOS

Question

I have a small CentOS server (minimal installation). It has HDD connected, but this HDD is not partitioned. Just a blank unused drive for future tasks. I want this HDD to stay in sleep mode when it is not used. It has the following spindown settings

hdparm -B 127 -S 240 /dev/sdb #(Sleep after 20min of inactivity.)

Despite this configuration, something still wakes this HDD up ~4 times per day without doing nothing. So, is there a way to trace what process wakes this drive up? I couldn't find any config file, where sdb is mentioned. No cron jobs or anything. It's a minimal CentOS installation.

Thanks!

Answer 1

I'll answer this myself.

The drive was woken up by smartd, which polls disks every 30 minutes by default. It has the following config line (/etc/smartmontools/smartd.conf):

DEVICESCAN -H -m root -M exec /usr/libexec/smartmontools/smartdnotify -n standby,10,q

This line tells smartd to check all identified disks. And -n standby,10,q tells it to quietly ignore any disks in standby mode, but wake them up after 10 failed attempts.

So, basically, i changed 10 to 671, meaning now the disk will be in sleep mode up to 2 weeks.