scsi interface specification - Plasmon

DRIVE COMMAND SETMEDIA SCAN (38H)MEDIA SCAN (38H)The MEDIA SCAN command requests the Target to scan the media for a contiguous set of written or blanklogical blocks.MEDIA SCAN Command (38H)BITBYTE7 6 5 4 3 2 1 000 MEDIA SCAN (38H)01 LUN 0 WBS ASA Reserved PRA Reserved02 Logical Block Address (MSB)03 Logical Block Address04 Logical Block Address05 Logical Block Address (LSB)06 Reserved07 Reserved08 Parameter List Length09 Reserved IgnoreErrorsWritten Block Search (WBS)A Written Block Search (WBS) bit of zero indicates that the scan is for blank blocks. A WBS bit of oneindicates that the scan is for written blocks.Advanced Scan Algorithm (ASA)An Advanced Scan Algorithm (ASA) bit of zero indicates that the scan area is scanned in sequential orderbeginning with the address specified in the Logical Block Address field. An ASA bit of one indicates that amodified binary scan algorithm will be used. This binary search can be used over a "mixed area" of blankand written blocks as long as the requested size of blank or written blocks (Number of Blocks Requestedfield) is not satisfied within the mixed area.The ASA assumes sequential use of the LBA space and is best suited for finding the high water mark in auser data area. Directory and other media mapping areas should use the sequential scan, provided thearea size does not produce a significant increase in execution overhead.Partial Results Acceptable (PRA)A Partial Results Acceptable (PRA) bit of zero indicates that the scan will not be satisfied until a contiguousset of blocks is found within the scan area, which is greater than or equal in size to the number of blocksrequested, and meets the other criteria for the scan.A PRA bit of one indicates that the scan may be satisfied by a contiguous set of blocks within the scanarea, which is less than the number of blocks requested, and meets the other criteria for the scan. In thiscase, the LaserDrive will report the largest contiguous set of blocks in the scan area. When the PRA bit isset, the ASA bit cannot be set.Ignore ErrorsReservedIf the Ignore Errors field is set to one, the LaserDrive will treat media errors as nonblank and access errorsas blank. If this field is not set, all errors will be reported when they are encountered.97653978 HPage 65