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START-SNAP-SESSION Creates a snap pair

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Storage system:

ETERNUS DX/AF

Domain:

DEVICE

Privileges:

TSOS


/START-SNAP-SESSION
creates one or more snap pairs by assigning one virtual device to an original unit as a snap unit.

The original units of the snap pairs are specified in the UNIT operand.

As an alternative original units can be chosen indirectly by using a SF pubset or Volume Set of a SM pubsets. In this case the pubset is selected using UNIT. In SNAP-UNIT a list of volumes is specified which are not yet being used as snap units and whose number matches the number of units in the pubset.

SHC-OSD checks the global and task-specific security settings before this command is executed (see "Security settings of SHC-OSD"). The current security settings can be displayed with /SHOW-SHC-PROCESSING (see also "SHOW-SHC-PROCESSING Displays settings of SHC-OSD"). They can be changed in the SHC-OSD parameter file (see "Configuration of SHC-OSD") for the next time SHC-OSD is started or with /MODIFY-SHC-PROCESSING for ongoing operations (see "MODIFY-SHC-PROCESSING Changes settings of SHC-OSD").

For SnapOPC+

The file consistency over multiple volumes must be ensured by the caller. For this purpose a synchronization point should be created for the data before the command is called, see section "Synchronization point for replications".

The server itself can access the snap unit immediately.

The snap pairs are activated immediately. From the application’s viewpoint, the snap unit contains all the data of the original unit at command processing time. On command execution, the snap session assumes the COPY-ON-WRITE status.

The devices for the original unit and snap unit must be contained in the same storage system and be of the same type. The configured size of the snap unit must be greater than or equal to the size of the original unit.

For ETERNUS DX/AF random Thin Devices or Flex Volumes can be used as snap units.
For ETERNUS DX/AF preconfigured snap data volumes (SDV) can be used as snap units.

A maximum of 256 snap units can be configured for an original unit.

The snap pubset on the snap units can be renamed directly using the NEW-PUBSET operand if an SF pubset is involved.

When the data backup with Snapsets is used for pubsets (see the “Introduction to System Administration” manual [5]), SnapOPC+ may not be used for this pubset. 


START-SNAP-SESSION

UNIT = *BY-PUBSET(...) / *BY-STORAGE(...) / <alphanum-name 2..2> /




<x-text 4..4>


*BY-PUBSET(...)



|

PUBSET = <cat-id 1..4>



|

,NEW-PUBSET = *SAME / *SPECIAL-VSN / <cat-id 1..4>



|

,HOLD-IO = *NO / *UNTIL-ACTIVATED


*BY-STORAGE(...)



|

SERIAL-NUMBER = <alphanum-name 3..14>



|

,LOGICAL-VOLUME = <x-text 1..4>

,SNAP-UNIT *BY-STORAGE(...) / *AUTO-SELECT /





list-poss(256): <alphanum-name 2..2> / <x-text 4..4>


*BY-STORAGE(...)



|

SNAP-LOGICAL-VOLUME = <x-text 1..4>

,SELECT = *STD / *TARGET-UNIT


UNIT =

Selects the original units by means of a particular catalog ID (*BY-PUBSET), via the serial number and the internal number of the logical volume in the storage system (*BY-STORAGE), or directly by means of the mnemonic device name of the logical volume.

UNIT = *BY-PUBSET(...)
Selects units by means of a pubset ID or volume set ID. The pubset is protected against reconfiguration during command processing.
When an SF pubset is selected, the volumes of the snap pubset generated can be renamed directly using NEW-PUBSET.

PUBSET = <cat-id 1..4>
Specifies the pubset ID or volume set ID. When HOLD-IO=*UNTIL-ACTIVATED, no volume set ID may be specified.

NEW-PUBSET =
Determines the catalog ID of the snap pubsets of the snap units.

NEW-PUBSET = *SAME
The snap pubset is not renamed, i.e. it retains the same name.

NEW-PUBSET = *SPECIAL-VSN
All volumes of the snap units are automatically renamed to prevent confusion with the original. For this purpose the period in a VSN in point notation is changed to a colon (e.g. AA.001 to AA:001), or in PUB notation the PUB string is changed to P:B (e.g. PUBA01 to P:BA01).

NEW-PUBSET = <cat-id 1..4>
An SF pubset’s snap pubset is renamed by specifying the new catalog ID explicitly. The catalog ID can also differ in length from the PUBSET operand. The new snap pubset is also an SF pubset. An existing MRSCAT entry is used if it is of the correct type. If it is not, it is deleted and created again. See the notes in section "Renaming SF pubsets with SHC-OSD".

HOLD-IO =
Handles inputs/outputs on the snap pair during splitting (see “Consistent splitting of a pubset in the shared pubset network” in "Synchronization point for the snapshot").

HOLD-IO = *NO
The inputs/outputs on the original units are executed without any change. This can lead to data inconsistencies on the snap units for applications which are not suspended before splitting takes place.

HOLD-IO = *UNTIL-ACTIVATED
The inputs/outputs on the original units are suspended until all the imported pubset’s snap pairs are in the COPY-ON-WRITE status. Subsequently inputs/outputs to the units are resumed. If an error occurs when inputs/outputs are suspended or resumed, the command is aborted. The input/output activity may need to be resumed using /RESUME-IO.

UNIT = *BY-STORAGE(...)
Selects the unit by means of the internal number of the logical volume in the storage system.

SERIAL-NUMBER = <alphanum-name 3..14>
Specifies the serial number of the storage system (make sure it is unique!).

LOGICAL-VOLUME = <x-text 1..4>
Specifies the internal number of the logical volume in the storage system

UNIT = <alphanum-name 2..2> / <x-text 4..4>
Selects the unit by means of the mnemonic device name of the logical volume.


SNAP-UNIT =

Selects the snap units.

SNAP-UNIT = list-poss(256): <alphanum-name 2..2> / <x-text 4..4>
Specifies the mnemonic device name of the virtual device. A list is accepted only if a pubset was specified in the UNIT operand.

SNAP-UNIT = *BY-STORAGE(...)
Selects the snap unit by means of the internal number of the logical volume in the storage system.

SNAP-LOGICAL-VOLUME = <x-text 1..4>
Specifies the internal number of the logical volume in the storage system

SNAP-UNIT = *AUTO-SELECT
Automatic selection of suitable snap units by SHC-OSD. Snap units are just chosen if they have the exact same configured size as the original unit.
The snap units are selected in accordance with the storage system:

  • From the set of the existing free and attached BS2000 volumes in special notation, see section “Automatic selection of snap units” in "Freely selectable snap units".

  • If no BS2000 volumes in special notation are available, from the set of the existing free and attached Snap Data Volumes (SDV)


SELECT =

Defines whether the unit specified in the UNIT operand or (when remote replication is used) the target unit of a remote copy pair is selected as the original unit of the snap pair.

SELECT = *STD
Selects the unit which was defined in the UNIT operand.

SELECT = *TARGET-UNIT
Selects the target unit of a remote copy pair as the original unit. The relevant source unit is specified in the UNIT operand


Command processing

Message NDE1073 is output to SYSOUT for each device and distributed via routing code 0, i.e. it is logged in the CONSLOG file only. You will find detailed information on the CONSLOG file (log file) in the “Introduction to System Administration” manual [5]. 

Examples

/START-SNAP-SESSION UNIT=5000,SNAP-UNIT=5040
/START-SNAP-SESSION UNIT=5001,SNAP-UNIT=*AUTO-SELECT
/START-SNAP-SESSION UNIT=*BY-PUBSET(PUBSET=TFS),SNAP-UNIT=(5100,5101,5102)

(Pubset TFS consists of 3 units)

/START-SNAP-SESSION UNIT=*BY-PUBSET(PUBSET=A,NEW-PUBSET=C),
                    SELECT=*TARGET-UNIT 

(see "SnapOPC+ and REC"

Command return codes

(SC2)

SC1

Maincode

Meaning


0

CMD0001

Command executed successfully

1

0

NDE2003

Command successfully executed, no processing necessary

2

0

NDE2004

Command successfully executed but not yet completed


1

CMD0202

Syntax error


32

NDE2002

Internal error


64

CMD0087

Function not permitted in the current input mode or with the current task privileges


64

CMD0216

Required privilege not available


64

NDE1000

Device not found or not in the storage system


64

NDE1001

Device not attached


64

NDE1003

Data medium not online or not unique


64

NDE1004

Pubset not found or wrong pubset type


64

NDE1008

Volume cannot be allocated


64

NDE1015

Device not defined in BS2000


64

NDE1043

Pubset type not supported


64

NDE1044

NEW-PUBSET already exists


64

NDE1058

All free snap units reserved for snapset


64

NDE1100

Invalid pubset state


64

NDE1101

More than one sharer for pubset


64

NDE1102

Not all volumes could be allocated


64

NDE1103

No reconfiguration lock for pubset


64

NDE1105

Inconsistent pubset


64

NDE1108

SELECT=*TARGET-UNIT: UNIT is not a source unit


64

NDE1109

SELECT=*TARGET-UNIT: TARGET-UNIT not found


64NDE1110SELECT=*TARGET-UNIT: Remote Copy pair not synchron or IN-HOLD

64

NDE1140

Duplicate MN in MN list


64

NDE1142

Mirror pair already exists


64

NDE1171

Target unit is not unique


64

NDE1410

No or too few free and matching Snap units


64

NDE1430

No Snap function for device


64

NDE1431

Different number of devices for units and snap units


64

NDE1434

Virtual snap unit already used in other pair


64

NDE1435

Device is a virtual unit


64

NDE1437

MNs of the unit and of the snap unit are identical


64

NDE1438

Unit and virtual snap unit are different types


64

NDE1439

Unit and virtual snap unit on different storage systems


64

NDE1440

Incorrect state of unit (of a snap pair)


64

NDE1441

Incorrect state of snap unit


64

NDE1470

Type of SNAP-UNIT must not be mixed (SDV and Thin)


64

NDE1535

Device is a clone unit


64

NDE1800

Device not found or not in storage system


64NDE1802Error communicating with StorMan server

64NDE1803Management instance not available

64

NDE1810

Storage system’s operating system version not supported


64

NDE1812

StorMan server switched off by command


64

NDE1814

Storage system’s serial number not found


64

NDE1815

Storage system’s serial number not unique


64

NDE1816

Storage system’s logical volume not found


64

NDE1820

Reconstruction in storage system not yet completed


64

NDE1833

No suitable Storman server found

64   

NDE1840

Unit and Snap unit on different storage systems

64   

NDE1850

All mirror disks of the unit reserved for snapset use

64   

NDE1852

Maximum number of local mirrors exceeded


64

NDE1853

Storage unit locked


64

NDE1870

Snap pair created


64

NDE1872

Automatic attachment of snap unit(s) failed


64

NDE1880

Copy license not installed (ETERNUS DX/AF)


64

NDE1881

Copy Table Size not configured (ETERNUS DX/AF)


64

NDE1882

Copy Table Size too small (ETERNUS DX/AF)


64

NDE1883

Advanced Copy operations for devices locked (ETERNUS DX/AF)


64

NDE2000

Execution partially successful


64

NDE2001

Command not executed


64

NDE2009

Command aborted with K2 key


64

NDE2014

StorMan error in command


130

NDE1082

Memory bottleneck during processing of command


130

NDE2005

Command cannot be executed at the moment