I think hdparm does not support all external disks, it depends on the disk.
I use two external disks connected to USB3 ports of my N2. One is supported by hdparm, the
other gives the same error message as you have seen.
If you have problems with hd-idle from the system-plugin, you can compile it by your own.
You can download the source from https://sourceforge.net/projects/hd-idle.
It is only one binary file, I stored it as /storage/.kodi/userdata/hd-idle
and put the following lines in autostart.sh:
# hdparm not working for all USB-disks -> use hd-idle
# disk idle after 10min
You have to compile hd-idle on your CE-box:
install GCC with entware, if not already done
1.b opkg install gcc
download and unpack the hd-idle source from the link above
Can confirm i added the autostart.sh with hdparm -S 120 /dev/sda1** => spindown in 10min
This seems to work perfectly, just what i needed. I still dont get why the unit does not automatically fall to sleep like it does on my pc?. Its really handy as the light then breaths to let you know its asleep.
This is working but light stays solid. Still i can now fall asleep knowing my drive will spin down and not be running all night.
Parking: Enable/Disable HDD parking on power off/suspend Parking Time: Time in seconds to wait for HDD to spin down when parking Idle Time: Time in minutes/hours until the HDD should enter suspend mode
I think that Anjuna asked a perfectly legitimate question that is something that I have often seen as a question of clarification in regards to use in Windows and other operating systems.
My understanding (which could also be incorrect) is that when idling, the hard drive platters are spun down. This reduces energy consumption to some degree but allows enough power to continue to be supplied to the drive for it to spring back into action relatively quickly.
Parking is essentially shutting down the hard drive such that it is in more or less the same state that it is when the box is switched off. This means even more energy being saved but when reactivating the disk, it takes longer to spring back into action, which, on occasion, can give the impression that things are slower than normal, but is just the time required to bring the disk back online.
If I am incorrect then I would say that it further legitimises the initial question asked.
Note: I’m not sure if either setting has any effect on solid state drives that have no mechanical processes to idle or park but there may perhaps be scope for idle in terms of a power saving mode of operation.