Has anyone got experiences they can share of attaching various 2.5" disk enclosures to a Pi? Ideally I'd like to buy a powered enclosure so I don't need a powered USB hub between it and the Pi.
I've currently got a 3.5" enclosure with a Cypress chipset that's working fine but the Power consumption is a little heavy for 24/7 operation. I've also got a USB3 enclosure with ASMedia AS2105 chipset but it's very unstable when attached to the Pi.
I don't think it matters much where the power brick is attached - USB hub or direct to the disk enclosure. The real issues are the relative efficiency of the USB hub's brick vs the disk enclosure's brick. If the disk will be unmounted and spun down most of the time, e.g. because its being used to do over night backups, then you'll care about the brick's power use when its idle. OTOH, if the drive is permanently mounted and spinning most of the time you'll be more interested in the total power consumption of brick and disk drive. Work out how much of the time the disk will be up and spinning and use that to decide which set of figures you'll need to compare.
Good luck, though, in getting reliable numbers without buying both powered and unpowered hubs and powered and unpowered disk enclosures plus a mains wattmeter and making the measurements yourself.
About all you can easily do is to buy one of the low consumption 2.5" drives. A quick glance at eBuyer seems to show that the available 2.5" enclosures are all USB powered while the 5.3" ones have a power brick, and that none of them give any details about the brick apart from saying "Yes, we supply one".
The Pi only has USB 2 ports, so there's no point in using a a USB3 enclosure anyway.
martin@ | Martin Gregorie
gregorie. | Essex, UK