hdparm APM_level is changing to 1 automaticly

[Sergey Skripnick]

Calling 'hdparm -B 255 /dev/sdb' seems take effect:

# hdparm -B /dev/sdb

/dev/sdb:
 APM_level = off

But in few minutes hdd is spinning down and

# hdparm -B /dev/sdb

/dev/sdb:
 APM_level = 1

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: hdparm 9.43-1ubuntu3
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed Jan 27 22:25:07 2016
Dependencies:
 gcc-5-base 5.2.1-22ubuntu2
 libc6 2.21-0ubuntu4
 libgcc1 1:5.2.1-22ubuntu2
 powermgmt-base 1.31+nmu1
InstallationDate: Installed on 2015-11-02 (86 days ago)
InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: hdparm
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.apm.event.d.20hdparm: [modified]
mtime.conffile..etc.apm.event.d.20hdparm: 2016-01-27T15:51:39.218897

[Sergey Skripnick (eyerediskin)]

> modified.conffile..etc.apm.event.d.20hdparm: [modified]

I've just changed APMD_SPINDOWN=255. No effect.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[eni (enienimail-ubuntu)]

Same problem in Xubuntu 14.04.5
I have two external drives, but only one of them has this bug.
Both are from Toshiba. Any ideas how to fix it? I already did:
sudo gedit /etc/hdparm.conf

and filled in following entries:
/dev/sdb {
        apm = 254
 apm_battery = 254
 spindown_time = 12
}
/dev/sdc {
        apm = 254
 apm_battery = 254
 spindown_time = 12
}
/dev/sdd {
 apm = 254
 apm_battery = 254
 spindown_time = 12
}

Why does Ubuntu toggle my HDD down to 1? Maybe set 254 for it's specific UUID? Could this fix it?