R and DVD device requirements?
Read and write access to CD-ROM, CD-R and CD-RW devices on ATA (IDE) is generally handled transparently by SYS$DQDRIVER, and SYS$DQDRIVER will transparently block and de-block the media-native 2048 byte disk blocks with the 512 byte blocks expected by OpenVMS and by native OpenVMS software. Read access to CD-ROM, CD-R and CD-RW devices on SCSI is handled by DKDRIVER, though SYS$DKDRIVER will not transparently de-block the native 2048 byte disk blocks into the 512 byte blocks expected by OpenVMS. The drive or external software is expected to provide this de-blocking, thus either a 512-byte-block capable drive (such as all RRD-series SCSI CD-ROM drives) is required, or host software is required for a 2048-byte block drive. SCSI drives with UNIX or 512-byte selectors will generally operate. At least some of the Plextor PlexWriter SCSI drives can be accessed from OpenVMS, and at least one Pioneer SCSI DVD drive (for CD media). The Pioneer SCSI DVD drive switches to 2048 byte blocks for DVD
