Persistent Reserve In - 5Eh

The PERSISTENT RESERVE IN CDB format is shown in the following table.

Table 1: PERSISTENT RESERVE IN CDB format

Bit Byte	7	6	5	4	3	2	1	0
0	Op Code (5Eh)
1	Logical Unit Number			Service Action
2	Reserved
2	Reserved
3	Reserved
3	Reserved
4	Reserved
4	Reserved
5	Reserved
5	Reserved
6	Reserved
7	Allocation Length
8	Allocation Length
9	Control

Field	Description
Service Action	This field specifies the type of request being made as follows: 0h – Read all registered reservation keys. 1h – Read all current persistent reservations. 2h – Report capabilities of the supported persistent reservation features (only supported if the command is issued to a media changer device hosted by a tape drive). 3h – Report full status of registration and reservation status for each registered I_T nexus (only supported if the command is issued to a media changer device hosted by a tape drive).
Allocation Length	This field specifies the byte length allowed for returning the requested data. The number of bytes returned is the lesser of the available data to return or the allocation length.

Field

Description

Service Action

This field specifies the type of request being made as follows:

0h – Read all registered reservation keys.
1h – Read all current persistent reservations.
2h – Report capabilities of the supported persistent reservation features (only supported if the command is issued to a media changer device hosted by a tape drive).
3h – Report full status of registration and reservation status for each registered I_T nexus (only supported if the command is issued to a media changer device hosted by a tape drive).

Allocation Length

This field specifies the byte length allowed for returning the requested data. The number of bytes returned is the lesser of the available data to return or the allocation length.

Persistent Reserve In Response

Response data is returned depending on the requested service action.

Read Keys Response

The response for a Read Keys service action is shown the following table.

Table 2: Read Keys Response

Bit Byte	7	6	5	4	3	2	1	0
0 : 3	Generation
0 : 3	Generation
4 : 7	Additional Length (n-7)
4 : 7	Additional Length (n-7)
Reservation Key List
Reservation Key List
8 : 15	First Reservation Key
8 : 15	First Reservation Key
:
:
n-7 : n	Last Reservation Key
n-7 : n	Last Reservation Key

Field	Description
Generation	This field is a 32-bit counter that is incremented every time a PERSISTENT RESERVE OUT command requests a Register, a Register and Ignore Existing Key, a Clear, a Preempt, or a Preempt and Abort service action. This counter is not maintained across power cycles.
Additional Length	This field indicates the length in bytes of the Reservation Key List.
Reservation Key List	This is a list of all the 8-byte reservation keys that have been registered through the PERSISTENT RESERVE OUT command.

Read Reservations Response

The response for a Read Reservations service action is shown in the following table.

Table 3: Read Reservations Response

Bit Byte	7	6	5	4	3	2	1	0
0 : 3	Generation
0 : 3	Generation
4 : 7	Additional Length (0 or 0010h)
4 : 7	Additional Length (0 or 0010h)
Reservation Descriptor
Reservation Descriptor
8 : 15	Reservation Key
8 : 15	Reservation Key
16 : 19	Scope-Specific Address
16 : 19	Scope-Specific Address
20	Reserved
21	Scope				Type
22	Obsolete
23	Obsolete

Field	Description
Generation	This field is a 32-bit counter that is incremented every time a PERSISTENT RESERVE OUT command requests a Register, a Register and Ignore Existing Key, a Clear, a Preempt, or a Preempt and Abort service action. This counter is not maintained across power cycles.
Additional Length	This field indicates the length in bytes of the Reservation Descriptor, which may return 0 or 0010h (16). Since element reservations are not supported, a single reservation descriptor is returned for logical unit.
Reservation Key	This is the 8-byte reservation key that was registered through the PERSISTENT RESERVE OUT command.
Scope-Specific Address	Element reservations are not supported and this field returns 0000h.
Scope	This field returns a 0h, indicating logical unit scope. Element scope is not supported.
Type	This field returns the type of reservation as follows: 3h Exclusive Access – The initiator holding the persistent reservation has exclusive read and write access. Requests from any other initiators to transfer data to or from the logical unit will result in a Reservation Conflict. 6h Exclusive Access, Registrants Only – Any currently registered initiator has exclusive data transfer access. Requests from unregistered initiators to transfer data to or from the logical unit will result in a Reservation Conflict. 8h Exclusive Access, All Registrants (only supported if the command is issued to a media changer device hosted by an HP tape drive).

Report Capabilities Response

This response contains a bit map that indicates the persistent reservation types that are supported by the device server.

Table 4: Report Capabilities Response

Bit Byte	7	6	5	4	3	2	1	0
0	Length (0008h)
1	Length (0008h)
2	Reserved			CRH	SIP_C	ATP_C	Rsvd	PTPL_C
3	TMV	Reserved						PTPL_A
4	WR_EX_AR	EX_AC_RO	WX_EX_RO	Rsvd	EX_AC	Rsvd	WR_EX	Rsvd
5	Reserved							EX_AC_AR
6	Reserved
7	Reserved

Field	Description
Length	This field reports 8 bytes of data.
CRH	A compatible reservation handling (CRH) bit set to one indicates that the device server supports the exceptions to the SPC-defined RESERVE commands and RELEASE commands. A CRH bit set to zero indicates that RESERVE commands and RELEASE commands are processed as defined in the SPC.
SIP_C	A specify initiator ports capable (SIP_C) bit set to one indicates that the device server supports the SPEC_I_PT bit in the PERSISTENT RESERVE OUT command parameter data. An SIP_C bit set to zero indicates that the device server does not support the SPEC_I_PT bit in the PERSISTENT RESERVE OUT command parameter data
ATP_C	An all target ports capable (ATP_C) bit set to one indicates that the device server supports the ALL_TG_PT bit in the PERSISTENT RESERVE OUT command parameter data. An ATP_C bit set to zero indicates that the device server does not support the ALL_TG_PT bit in the PERSISTENT RESERVE OUT command parameter data.
PTPL_C	A persist through power loss capable (PTPL_C) bit set to one indicates that the device server supports the persist through power loss capability for persistent reservations and the APTPL bit in the PERSISTENT RESERVE OUT command parameter data. An PTPL_C bit set to zero indicates that the device server does not support the persist through power loss capability.
TMV	A type mask valid (TMV) bit set to one indicates that the PERSISTENT RESERVATION TYPE MASK field contains a bit map indicating which persistent reservation types are supported by the device server. A TMV bit set to zero indicates that the PERSISTENT RESERVATION TYPE MASK field shall be ignored.
PTPL_A	A Persist Through Power Loss Activated (PTPL_A) bit set to one indicates that the persist through power loss capability is activated. A PTPL_A bit set to zero indicates that the persist through power loss capability is not activated
WR_EX_AR	A Write Exclusive – All Registrants (WR_EX_AR) bit set to one indicates that the device server supports the Write Exclusive – All Registrants persistent reservation type. An WR_EX_AR bit set to zero indicates that the device server does not support the Write Exclusive – All Registrants persistent reservation type.
EX_AC_RO	An Exclusive Access – Registrants Only (EX_AC_RO) bit set to one indicates that the device server supports the Exclusive Access – Registrants Only persistent reservation type. An EX_AC_RO bit set to zero indicates that the device server does not support the Exclusive Access – Registrants Only persistent reservation type.
WX_EX_RO	A Write Exclusive – Registrants Only (WR_EX_RO) bit set to one indicates that the device server supports the Write Exclusive – Registrants Only persistent reservation type. An WR_EX_RO bit set to zero indicates that the device server does not support the Write Exclusive – Registrants Only persistent reservation type.
EX_AC	An Exclusive Access (EX_AC) bit set to one indicates that the device server supports the Exclusive Access persistent reservation type. An EX_AC bit set to zero indicates that the device server does not support the Exclusive Access persistent reservation type.
WR_EX	A Write Exclusive (WR_EX) bit set to one indicates that the device server supports the Write Exclusive persistent reservation type. An WR_EX bit set to zero indicates that the device server does not support the Write Exclusive persistent reservation type.
EX_AC_AR	An Exclusive Access – All Registrants (EX_AC_AR) bit set to one indicates that the device server supports the Exclusive Access – All Registrants persistent reservation type. An EX_AC_AR bit set to zero indicates that the device server does not support the Exclusive Access – All Registrants persistent reservation type.

Report Full Status

The response for a Report Full Status service action is shown in the following table.

Table 5: Report Full Status

Bit Byte	7	6	5	4	3	2	1	0
0 : 3	Generation
0 : 3	Generation
4 : 7	Additional Length (n-7)
4 : 7	Additional Length (n-7)
Full Status Descriptors (see Table 6)
8 : 15	First Full Status Descriptor
8 : 15	First Full Status Descriptor
:
n - 7 : n	Last Full Status Descriptor
n - 7 : n	Last Full Status Descriptor

Field	Description
Generation	This field is a 32-bit counter that is incremented every time a PERSISTENT RESERVE OUT command requests a Register, a Register and Ignore Existing Key, a Clear, a Preempt, or a Preempt and Abort service action. This counter is not maintained across power cycles.
Additional Length (n-7)	This field indicates the length in bytes of the Reservation Descriptor,
Full Status Descriptor	The response for a Full Status Descriptor is shown in the table below.

Table 6: Full Status Descriptor

Bit Byte	7	6	5	4	3	2	1	0
0 : 7	Reservation Key
0 : 7	Reservation Key
8 : 11	Reserved
8 : 11	Reserved
12	Reserved						ALL_TG_PT (0)	R_Holder
13	Scope				Type
14 : 17	Reserved
14 : 17	Reserved
18	Relative Target Port Identifier
19	Relative Target Port Identifier
20 : 23	Additional Descriptor Length
20 : 23	Additional Descriptor Length
24 : n	Transport ID
24 : n	Transport ID

Field	Description
Reservation Key	This is the 8-byte reservation key that was registered through the PERSISTENT RESERVE OUT command.
ALL_TG_PT (0)	This bit is not supported and is ignored.
R_Holder	Set to 1 to indicate that the I-T nexus is a Persistent Reservation Holder.
Scope	This field returns a 0h, indicating logical unit scope. Element scope is not supported.
Type	This field returns the type of reservation as follows: 3h Exclusive Access – The initiator holding the persistent reservation has exclusive read and write access. Requests from any other initiators to transfer data to or from the logical unit will result in a Reservation Conflict. 6h Exclusive Access, Registrants Only – Any currently registered initiator has exclusive data transfer access. Requests from unregistered initiators to transfer data to or from the logical unit will result in a Reservation Conflict. 8h Exclusive Access, All Registrants (only supported if the command is issued to a media changer device hosted by an HP tape drive).
Relative Target Port Identifier	Relative target port identification descriptor (Table 11
Transport _ID	See details in PERSISTENT RESERVE OUT command (Persistent Reserve In - 5Eh and Persistent Reserve In - 5Eh).