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Chapter 3 Media Changer Commands
Persistent Reserve In Command (5Eh)
96 Quantum ATL SuperLoader Software Interface Guide
Table 42
Read
Reservations
Parameters
The figure and table below illustrate and describe the data fields of
each Read Reservations descriptor’s data fields.
Field Name Description
Generation The value in this field is a 32-bit counter in the device server that is
incremented each time a PERSISTENT RESERVE OUT command requests a
Register, Clear, Pre-empt, or Pre-empt and Clear operation. Note that
PERSISTENT RESERVE IN commands do not increment the counter, nor do
PERSISTENT RESERVE OUT commands that perform a Reserve or Release
service action, or by a PERSISTENT RESERVE OUT command that is not done
due to an error or a reservation conflict. The value in the Generation field is set
to 0 as part of the power on or reset processes.
The value in the Generation field allows the application client that examines
the value to verify that the configuration of the initiators attached to a logical
unit has not been modified by another application client without any
notification of the application client doing the examination.
Additional
Length
This field contains the count of the number of bytes of Reservation descriptors
(bytes 8 – n ). Note that this field contains the number of bytes regardless of the
value prescribed by the Allocation Length field in the command’s CDB.
Reservations
Descriptors
One Reservation descriptor is reported for each unique persistent reservation
on the logical unit when the PERSISTENT RESERVE IN command has
indicated a Read Reservations action. Figure 53 on page 97 and table 43 on
page 97 detail the contents of each Reservation Descriptors field.