The Resouce Package gives a good description of mode pages, which helps a lot for users on unsupported platforms like Linux. But, there are a few things missing. It only gives a brief description of commands, and does not define how they are used.

For users with unsupported filesystems like ext3, this makes it possible to find the actual number of sectors in order to create a fixed-size partition that matches the actual capacity. There is a SCSI command SET_USED_CAPACITY which may make it possible to keep the capacity LEDs in sync with the filesystem's usage.

reading stuff is clear, but need a sample of writing to the device (or as Joe says "commands"). The manual is indeed unclear, need a write sample...

1. what are the pages for the arguments/parameters for each command.
2. manual says operations should be synchronous, but doesn't talk about ioctl returns.  I imagine the ioctl returns immediately, and we have to poll to query the completion status, and not do anything while it is pending.
3. some hints, but it isn't clear how to check on the return status after issuing a command.

in luninfo2, what is partition type for, and how is it set?

similar for disk partition type...

If I just load up parted, and write a (gpt) partition table, and create a file system, will this stuff be magically detected and  updated?  Or is there some magic required to tell the drobo, that sort of thing?

Thanks Mark,

 I figured out the luninfo2 stuff.   I formatted my drobo with ext3, and it noticed, and the lights luninfo just notice how things are and work... after a while.