I wonder if using ext2ls to list files in /test dir on each drive when used with Hush Shell commands to check if a certain file was listed will allow to test drive presence:
$this->bbcode_second_pass_code('', 'ext2ls usb 0:1 /test')
In that approach a user would add a small file to /test on each drive beforehand, and create a small EXT2 volume where absent, since ext2ls can't mount other partition types. Somewhat limiting, but may do the job regardless of any drive combo connected. Original Pogoplug allows to mount drives in Win via Samba by adding beforehand certain config files to each drive - a similar idea.
Another approach to look at is trying to use usb dev [dev] and ide device [dev] Uboot commands to test drives presence:
$this->bbcode_second_pass_code('', 'GoFlexNet> ide device 1
IDE device 1: not available
GoFlexNet> ide device0
IDE device 0: Model: TOSHIBA MK6034GSX Firm: AH105B Ser#: 82FS7142K
Type: Hard Disk
Supports 48-bit addressing
Capacity: 57231.5 MB = 55.8 GB (117210240 x 512)')
Of course, there are more options to try, given a will exists to resolve the issue instead of jumping on messengers. Its an obvious deficiency of both Uboot and ArchLinux, since they can't do it together at the moment.
$this->bbcode_second_pass_quote('moonman', 't')here is no easy way to test again sata drive presence and your pseudo-code makes absolutely no sense