Logical drives on aacraid-based controllers are ignored by the installer 
because the disks are flagged "removable" by the driver.

Using the driver disk I created for the aacraid driver, (and hitting 
Cancel after a couple passes through the "Please insert your driver disk 
labeled ... again, again, again", it loaded the aacraid driver. However, 
later I hit the message "no valid devices were found on which to create 
new filesystems". Going to Alt-F3, I see the messages "Not in expert mode, 
ignoring removable device sd[abc]".

Adaptec has set the removable device flag on the aacraid-controlled 
devices, because while the system is running, root may use a management 
app to add or delete a virtual drive.