6-12-90 X3T9.2/90-87 TO: X3T9.2 / SCSI-2 FROM: Thomas Wicklund / Ciprico, Inc. RE: Sequential device partition definition While working with two DAT drives Ciprico has found that the manufacturers have used different interpretations of the Medium Partition Page(1). I have read the standard and it isn't clear which interpretation is correct or whether the document is ambiguous. The Medium Parition Page(1) specifies the number of additional partitions (Additional Partitions Defined). It appears that if a device has N partitions, this field will be set to N-1. So far everybody appears to agree. The ambiguity is in the use of the Partition Size Descriptor list. If the device has N partitions, should there be N Partition Size descriptors? Or should there be N-1 (matching the Additional Partitions Defined field) listing partitions 1.. N with partition 0 assumed the remainder of the tape. We've seen these two interpretations. One drive requires one Parition Size descriptor (partition 1) and assumes partition 0 is the rest of the tape. The other requires two Partition Size descriptors and ignores the first one (partition 0), instead using the rest of the tape. Media is interchangeable between the drives but our software must contain special checks to determine which drive is being used. The Partition Size field description does not state how partitions in the list translate into partition numbers, so I'm not sure which drive's interpretation is correct (or if neither are correct). It may help to clarify the intent of this field before inconsistent implementations become common.