For the record.  The new drive was only assigned a SCSI address, and therefore became visible, when  the existing Logical Library was re-built.
Hello,            I have been using the mtx  command,  under Rocky Linux 8,  to operate a ML£ tape library with two SAS LTO  drives The relevant  generic SCSI devices are shown by the output of lsscsi .: [1:0:6:0] tape IBM ULT3580-HH6 KAJ9 /dev/st0 /dev/sg1[1:0:7:0] tape IBM ULT3580-HH8 N4Q1 /dev/st1 /dev/sg3[1:0:7:1] mediumx IBM 3573-TL 1500 /dev/sch0 /dev/sg4 However, after the second (LTO-6)   drive was installed it was not recognised by mtx. This is illustrated by he output of mtx compiled with a debug flag enabled:: [root[NAME] ~]# mtx.debug status0000: 17 00 00 00 9D 12 00 00 00 01 03 E9 00 23 00 65 '.............#.e'0010: 00 05 00 01 00 01 00 00 20 20 20 20 20 20 '........ '*sense_page=9d 9drawNumStorage= 0 35 rawNumImportExport= 0 5rawNumTransport=0 1 rawNumDataTransfer=0 1NumMediumTransport=1NumStorage=40NumImportExport=5NumDataTransfer=1MaxReadElementStatusData=3568NumElements=42Storage Changer /dev/sg4:1 Drives, 40 Slots ( 5 Import/Export )Data Transfer Element 0:EmptyStorage Element 1:Empty From above query it can be seen that 35 storage slots  are counted  but only one data transfer slot ( tape drive). Nb the Web  administration  interface shows that both drives are online..   I reset the Library , but this hasn't fixed  the issue.  I am running mtx version 1.3.12 ; that dates back to 2008 - was wondering i if anyone else has tried using it to operate an ML3?   For the record,  it works well enough for loading and unloading tapes and reading barcodes.
ML3 Tape Library and 'mtx' command drive count