An anonymous reader writes: 've been trying to come up with a very low power overhead way to share a disk between two systems. The goal is a cluster that uses less than 5 watts total when under low load (panda board; USB attached disk), and can kick up to a more powerful x86 based system as needed (rarely). The power budget of 5 watts in low power mode is a hard budget.
Dual port 2.5" 5400-7200 rpm SATA disks would be ideal (if they existed). Using a SATA to dual port SAS interposer or 2.5" dual port SAS disk is out unless someone knows of a SAS to USB adapter-- I could not find such a thing.
Firewire could be an option, as there are some dual port enclosures available, but I would need some sort of firewire to USB adapter.
Using a NAS, even something like a single disk WD mybook uses more power by itself than I want the entire system to use when in low power mode.
Using the panda to serve up its usb attached disk to the more powerful system e.g., over NFS is less than ideal due to IO requirements when under load. But, so far this seems to be the only way to make this system work within the other design constraints.
Ideas? I expect, "Poster has impossible requirements, and can't find a solution." responses, but I hope someone will have something. A link to some obscure SAS to USB adapter on a site that Google doesn't index, though improbable, would be very nice. Or, a completely different way to approach problem, keeping in mind the hard requirement for 5W power budget for the low power mode, and moderately heavy IO for the rare high power mode.