User's Guide

Chapter 2 Emulated Medium Changer SCSI Commands
Reserve (16h)
Quantum DX-Series Software Interface Guide 97
• An initiator that holds a current reservation may modify that
reservation (for example, to switch third-parties) by issuing
another Reserve Unit to the DX-Series system
• Element and Reservation ID
The field specifies if this command is a Unit Release.
• If the value is zero, the command releases a reservation placed on
this unit by the requesting initiator that meets 3rd party release
requirements, if applicable
• Element List Length
Only valid if Element is 1, otherwise this field is reserved and must
contain 0s. This field specifies Length of Element List Descriptors
(see
table 63) that follow. This value must be a whole multiple of the
length of a single Element List Descriptor (6).
Table 63 Element List
Descriptor
Bit/Byte 7 6 5 4 3 2 1 0
0
1
2
3
4
5
•Flag Bit
The Flag bit is used in conjunction with the Link bit to notify the
initiator in an expedient manner that a command has been
completed.
Flag bits are not supported by the DX-Series system.
•Link Bit
A Link bit set to 1 indicates that the initiator requests continuation of
a task (an I/O process) across two or more SCSI commands.
Reserved (0000h)
(MSB)
Number of Elements
(LSB)
(MSB)
Starting Element Address
(LSB)