I've been going through the forums, and while the consensus seems to be "Use multiple LUNs", it seems that there are other ways to do it using extents. On a clean install of ESXi 4.1, my 9.5 TB disk shelf (plain old SAS, not a SAN or anything) showed up just fine, but I needed to reformat with larger blocks so I could have bigger VMDK files.
I tried nuking it and adding through the normal means via the vSphere client: Add Storage, select LUN, pick block size, maximize capacity. It all looked well and good, but then the volume only showed up as 1.54 TB (noticeably, 8.00 short of max size).
I tried right clicking it, Properties, Increase, picked the same LUN, picked Free Space to add into, checked Max Capacity again, and got an error:
Call "HostDatastoreSystem.ExpandVmfsDatastore" for object "ha-datastoresystem" on ESXi "xxx.xxx.xxx.xxx" failed.
Operation failed, diagnostics report: Unable to grow Filesystem, please see VMkernel log for details.
/var/log messages says stuff like:
Jan 21 20:15:52 vmkernel: 0:20:14:47.753 cpu7:9971)WARNING: ScsiCore: 1399: Invalid sense buffer: error=0x0, valid=0x0, segment=0x0, key=0x0
