[Cisco2kid]

Using pi 3b and Kodi 17.6 with Libreelec.
Connected new 4-bay Mediasonic drive dock using USB.  Three drives.... older SATA IIs and brand new SATA III SSD.  The drives randomly unmount even when in use.
This DOES NOT happen with the same old drive and the SSD in an older Thermatake 2 bay dock at all.

I do notice that there is no message that the older drives auto mount after the SSD mount message, with either dock, but all the drives mount initially in both the new 4-bay and the older 2 bay.  I never do anything but let them automount.

Should I be changing somehow from automount?  I don't know if it is a spin up spin down problem?  Probably not, as the drive in use will still unmount.

I actually prefer if all drives stay mounted and spinning up all the time as I switch back and for queing media anyway.

Grateful for any suggestions.  Otherwise will toss the Mediasonic and warn others going back just to the 2 bay Thermaltake.

[Klojum]

Moved topic to the hardware section. (Yay, post #4000 for me )

[Cisco2kid]

thanks for the move... 4000... you deserve something

Ans. my own post... Mediasonic says small boards like a pi need a powered usb hub.  I guess I don't draw enough with just two normal big old drives... maybe three or the nature of an SSD causes larger power needs.  Anyway, even though the dock is powered of course, perhaps they are right...I will try a small powered hub between the usb out of the dock and usb in of the pi.  More later (I already packed the dock up).