All drives suddenly spin up.

[Nilsen]

I've been experiencing this a while, suddenly all drives will spin up for no apparent reason, anyone have any idea what can cause this?

 

I'm on 4.6

 

This is the last lines of the syslog when it happened just now, but nothing to gather from it:

 

Jun 12 01:53:06 Tower kernel: mdcmd (409): spindown 9 (Routine)
Jun 12 02:02:17 Tower kernel: mdcmd (410): spindown 0 (Routine)
Jun 12 02:40:10 Tower kernel: mdcmd (411): spindown 8 (Routine)

 

I'm using the cache_dirs script by the way, dont know if this can cause this?