Hard disk don't go to standby

[pandatuga]

Hello everyone,
Since the July updates I noticed that the harddisks on my TS-453A can stays hours/days without turning off/standby the WD RED disks.
Very few occasions I noticed that it works fine.

I already disabled most of the applications without any success, run the diagnostic utilities -blkdevMonitor_20151225.sh- that show very occasional activities (but no specific identifiable process):
<7>[ 1757.246917] setcfg(30931): dirtied inode 6923 (uLinux.conf) on md9
<7>[ 1762.634418] kjournald(2216): WRITE block 533992 on md9 (8 sectors)

Anyone experiencing this issue ?