HT1121 is "Promise VTrak: First SAS-connected Expansion Chassis Only: Xsan (Data Only) configuration script".
This script is to be used when adding the first expansion chassis to a Vtrak Used with Xsan. So it configures new arrays and LUNs with physical disks 17-32. So if you already have arrays using these disks, don't use this script. Arrays and drives (and the data on them) in the RAID head unit that the expansion chassis connects to (assuming its a 16 drive E610 unit) will not be affected by this script.
If you're unsure, you can always create the new arrays manually. (I would recommend this.) The manual instrctions are at the bottom of HT1200. If you do that, don't forget to do the quick init on new LUNs to remove old metadata if this expansion chassis was used before.