Twin Tailing and Search IML (Enhanced BIOS)
Twin-Tailing is the term used to refer to attaching one or more disks to two servers. It has the potential for sharing data and for increasing availability, but this is only hardware-level support for twin-tailing, which can be used for read-only files. Software support would need to be added to ensure that the same file was not being written to, at the same time, by both systems.
(may be dated)
and Search IML
Ed. I think I have the correct answer
for the SCSI bus termination.
This ignores any SCSI devices past the SCSI adapters. I _assume_ there is no termination between the systems
Search IML supports twin-tailing by enabling the SCSI adapters to use SCSI IDs 7 and 6, with the external disk being located on, for example, SCSI ID 5. Search IML will find and load the IML BIOS on this disk from both systems. Although both adapters support twin-tailing, the 32-bit IBM SCSI adapters are able to detect that twin-tailing is in operation, whereas the 16-bit IBM SCSI adapters are not.