Persistent Reserve Out - 5Fh

The library will perform service actions relative to persistent reservations as requested. This includes creating and clearing reservations.

An I_T nexus performing Persistent Reserve Out service actions is identified by a reservation key.

This command is only supported if the library control path is provided by a tape drive.

Note: IO blades connected to drives configured with a control path may report certain library ready conditions differently than drives without a control path configured.

This command is used in conjunction with PERSISTENT RESERVE IN to manage persistent reservations. It can be used to request exclusive access to the device. The PERSISTENT RESERVE IN and PERSISTENT RESERVE OUT commands should not be used with the RESERVE ELEMENT and RELEASE ELEMENT commands.

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

Table 1: PERSISTENT RESERVE OUT CDB format

Bit

Byte

7

6

5

4

3

2

1

0

0

Op Code (5Fh)

1

Logical Unit Number

Service Action

2

Scope

Type

3

:

6

 

Reserved

7

Parameter List Length (18h)

8

9

Control
Field Description
Service Action

This field specifies what reservation action to take as follows:

  • 00h Register – Register a reservation key without making a reservation.
  • 01h Reserve – Create a persistent reservation of the specified scope and type.
  • 02h Release – Releases the selected reservation for the requesting initiator.
  • 03h Clear – Clears all reservations keys and all persistent reservations.
  • 04h Preempt – Preempt reservations from another initiator.
  • 05h Preempt and Abort – Preempt reservations from another initiator and abort all tasks for all initiators with the specified reservation key.
  • 06h Register and Ignore Existing Key – Register a new reservation key and discard existing reservation key.
  • 07h – Register and Move Registers a reservation key for another I_T nexus and moves the persistent reservation to that I-T nexus.
Scope

Only logical unit scope is supported, and this field must be a 0h.
Type

This field specifies 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).
Parameter List Length

This field returns 18h (24) to indicate the length of the PERSISTENT RESERVE OUT parameter list, which is shown in the following table.

Table 2: PERSISTENT RESERVE OUT Parameter List

Bit

Byte

7

6

5

4

3

2

1

0

0

:

7

Reservation Key

8

:

15

Service Action Reservation Key

16

:

19

Scope-Specific Address

20

Reserved

SPEC-1_PT

ALL_TG_PT

Rsvd

APTPL

21

Reserved

22

:

23

Obsolete

24

:

n

 

Additional Parameter Data (see Table 3 and Table 4)
Field Description
Reservation Key

This is an 8-byte reservation key that identifies the initiator. The value must match the registered reservation key for the I_T nexus except for:

  • The Register and Ignore Existing Key service action, where this field is ignored.
  • The Register service action for an unregistered I_T nexus, where this field is 0.

If the Reservation Key does not match with the one registered in the device server for the I_T nexus, the device server returns Reservation Conflict.
Service Action Reservation Key

This field only applies to the following service actions as follows:

  • Register – This is the new reservation key to register.
  • Register and Ignore Existing Key – This is the new reservation key to register.
  • Preempt – This is the reservation key of the persistent reservation to preempt.
  • Preempt and Abort – This is the reservation key of the persistent reservation to preempt.

For the Register and Register and Ignore Existing Key service actions:

  • 0 – Unregisters the registered reservation key specified in the Reservation Key field.
  • n – The new reservation key to replace the existing one as specified in the Reservation Key field for the I_T nexus.

For the Preempt and Preempt and Abort service actions, this field contains:

  • n – The reservation key of registrations to be removed or, if this field also identifies a persistent reservation holder, the persistent reservation to be pre-empted.

For the Register and Move service action, this field contains:

  • n – The reservation key to be registered on the specified I_T nexus.
Scope-Specific Address

Element reservations are not supported and this field must be 0000h.
SPEC_I_PT

This bit is valid for the Register and Register and Ignore Existing Key service actions. Set to 0 to ignore the additional parameter data and apply the registration to the I_T nexus that sent the command. Set to 1 to have the additional parameter data include a list of transport IDs and apply the registration to the I_T nexus for every initiator port specified in the transport list
ALL_TG_PT

This bit is not supported and is ignored.
Activate Persist Through Power Loss (APTPL)

This bit is only valid for the Register, Register and Ignore Existing Key and Register and Move service actions. If set to 1, the logical unit preserves any persistent reservation and all registrations if power is lost and later returned. If the EEPROM (non-volatile memory) is unable to store data anymore, a CHECK CONDITION will be returned to reject the request.

If a library media changer device control path is configured via a DA blade, persistent reservations are not supported across power cycles, so this field must be set to 0.

Table 3: Additional Parameter Data

Bit

Byte

7

6

5

4

3

2

1

0

24

:

27

Transport Parameter Data length (n - 27)

Transport ID List (see Table 5 and Table 6)

28

:

First Transport ID

:

:

n

Last Transport ID

Field Description
Transport Parameter Data Length

Specifies the number of bytes of Transport IDs to follow.
Transport IDs

See Section Transport IDs below.

Table 4: Parameter Data for the Register and Move Service Action

Bit

Byte

7

6

5

4

3

2

1

0

0

:

7

Reservation Key

8

:

15

Service Action Reservation Key

16

Reserved

17

Reserved

Unreg

APTPL

18

 

Relative Target Port Identifier

19

20

:

23

 

Additional Descriptor Length (18h)

24

:

n

 

Transport ID
Field Description
Reservation Key

This is an 8-byte reservation key that identifies the initiator. The value must match the registered reservation key for the I_T nexus except for:

  • The Register and Ignore Existing Key service action, where this field is ignored.
  • The Register service action for an unregistered I_T nexus, where this field is 0.

If the Reservation Key does not match with the one registered in the device server for the I_T nexus, the device server returns Reservation Conflict.
Service Action Registration Key

Specifies the reservation key to be registered on the specified I_T nexus.
Unreg

Set to 1 to indicate that the I-T nexus on which the command was received be unregistered.
APTPL

Set to 1 to indicate that the logical unit preserve any persistent reservation and all registrations if power is lost and later returned. If the EEPROM (non-volatile memory) is unable to store data anymore, a CHECK CONDITION will be returned to reject the request
Relative Target Port Identifier Relative target port identification descriptor (Table 11
Transport ID See tables below.

Transport IDs

Table 5: Fibre Channel Transport IDs

Bit

Byte

7

6

5

4

3

2

1

0

0

Format Code (00b)

Reserved

Protocol Identifier (0h)

1

:

7

 

Reserved

8

:

15

 

World Wide Port Name (WWPN)

16

:

23

 

Reserved
Field Description
World Wide Port Name (WWPN) Unique identifier for Fibre Channel port.

Table 6: SAS Transport IDs

Bit

Byte

7

6

5

4

3

2

1

0

0

Format Code (00b)

Reserved

Protocol Identifier (6h)

1

:

3

 

Reserved

4

:

11

 

SAS Address

12

:

23

 

Reserved
Field Description
SAS Address Port address on SAS device.