Quantum DLT 8000 Product Manual page 350

SCSI Commands
RESERVE (10) Command (56h) (continued)
Table 5–91 RESERVE UNIT (10) Command — Field Descriptions (continued)
Field
Extent
Bit 7
Byte
0
(MSB)
1 - 3
(MSB)
4 - 7
5-206
Description
If 0, requests that the entire logical unit be reserved for use only by the
initiator until the request is supplanted by another valid RESERVE command
from the same initiator, or until released via a RELEASE (10) command from
the reserving initiator, a hard reset, or a power on cycle.
If set = 1, the extent reservation option is implemented. This option allows
an application client in a multitasking environment to have multiple
reservations.
The size of the extent list is defined by the contents of the Parameter List
Length field. The extent list consists of zero or more descriptors. Each
descriptor defines an extent beginning at the specified logical block address
for the specified number of blocks. If the number of blocks is 0, the extent
begins at the specified logical block address and continues through the last
logical block address on the logical unit. The data format of extent
descriptors is shown in Figure 5-93.
6 5
Reserved
Number of Blocks
Logical Block Address
Figure 5–93 Extent Descriptors — Data Format
Quantum DLT 8000 Tape System
4 3
RelAdr
2 1
Reservation Type
(LSB)
(LSB)
0