Hello Kurt,
CA Disk does not back up all parts of SAS multi-volume data sets created by SAS release 8.1 and earlier because SAS used a non-standard allocation method which caused the FMT1 on each volume to look like a stand-alone data set. Newer releases of SAS follow IBM standards for multi-volume data sets and these data sets can be successfully processed by BACKUP, BACKUPCC, ARCHIVE and RESTORE.
Hope that answer your question.
Pierre