Local disk partitions have "Eject" method not "Unmount"

Hi,

I have problem with handling partitions of my HDD (having root partition).
Drive has several partitions on it, if a partition is mounted and i right click on it, i see “Eject” action instead of “Unmount”
i get this both on the desktop icon and in Caja/Devices.

details:
system: Ubuntu Mate 16.04.1 LTS AMD64
HDD: device connected on eSata (maybe it is important)
it worked good in UM 15.10 , since i upgraded to 16.04.1 it doesn’t

how system decides which action (unmount, eject, safely remove) is shown for a given partition?

i read some documentation, askubuntu, etc
but it i feel lost in systemd, udisks2, udev jungle, so i need some help
thx in advance

I'm not seeing this on my system. I have an eSATA drive that is formatted NTFS and used for common data storage that's shared between Win 7 and Ubuntu.
I don't have the drive identified in /etc/fstab. When right clicked in Caja [ver 1.14.1] here are the options

i have Mate ver 1.12.1 (with Caja 1.12.7) that is part of standard installation.
kernel 4.4.0-34-generic also standard
i have 2 fstab lines as both my “/” and “swap” are on the drive,
but no line for other partitions

still I have Eject where you have Unmount
the question is why