Description

This document attempts to explain the steps required to create a BCV image of a SRDF (R1) device when using Veritas Volume Manager and DMP.

Note: The SRDF (R1) lun is in a write-enabled state at the time of the BCV copy operation.

In this instance, the configuration consists of "4" EMC SRDF "R1" devices presented to production server "Dopey" from EMC Symmetrix id (SID) "822".
An additional "4" EMC SRDF "R2" devices have been presented to DR server "Bashful" from EMC Symmetrix ID (SID) "414".


Note: As of 5.0 MP3 onwards, the VxVM CLI command "vxdisk -e list" is capable of reporting the extended attribute based content for EMC BCV, BCV-NR, MIRROR, SRDF-R1, SRDF-R2, TDEV device states and EMC lun types.


Figure 1.0

Steps:

In this instance, an EMC BCV image will be taken of the EMC SRDF lun "emc0_008c" to BCV lun "emc0_00f4"


1.] VxVM disk listing:
 

Dopey # vxdisk -e list
DEVICE       TYPE           DISK        GROUP        STATUS               OS_NATIVE_NAME   ATTR
emc0_00f4    auto:cdsdisk   -            -           online               c1t5006048C5368E5A0d281s2 bcv                  <<<< BCV image of "emc0_008c"
emc0_00f5    auto:cdsdisk   -            -           online               c1t5006048C5368E580d275s2 bcv
emc0_008c    auto:cdsdisk   r1-008C      DopeyDg     online               c1t5006048C5368E580d266s2 srdf-r1   <<<< SRDF R1 lun
emc0_008d    auto:cdsdisk   r1-008D      DopeyDg     online               c1t5006048C5368E5A0d223s2 srdf-r1
emc0_008e    auto:cdsdisk   r1-008E      DopeyDg     online               c1t5006048C5368E5A0d229s2 srdf-r1
emc0_008f    auto:cdsdisk   r1-008f      DopeyDg     online               c1t5006048C5368E580d269s2 srdf-r1


2.] As the EMC SRDF lun is already part of an existing EMC "DeviceGroup", a mapping file can be created and parsed by the EMC "symmir" command.

# cat /bcv-mapping.txt
008C 00F4


The EMC SYMDEV reference in the first column is the source lun "008C", which relates to Veritas disk access (da) name "emc0_008c".
The EMC SYMDEV reference in the second column is the target lun "00F4" for the EMC BCV device, which relates to Veritas disk access (da) name "emc0_00f4".


3.] Using the above "mapping" file the source to target device mappings will be formed.


Note: A "full" BCV establish is required in the first instance, to ensure all the data is copied from the source to target lun.


The EMC Symmetrix ID (SID) can be obtained from the Veritas DMP CLI command "vxdmpadm listenclosure all".

In this instance, the SID is " 000290300822", for which can be shortened to just three characters in length "822".


Dopey # vxdmpadm listenclosure all
ENCLR_NAME        ENCLR_TYPE     ENCLR_SNO      STATUS       ARRAY_TYPE     LUN_COUNT
===================================================================================
emc0              EMC            000290300822         CONNECTED    A/A         6



The "-v" option provides verbose output during the execution of the symmir command.


Dopey # symmir -sid 822 -v -f  /bcv-mapping.txt -full establish -nopr

'Full Establish' operation execution is in progress for the device list in device file '/bcv-mapping.txt'. Please wait...


SELECTING the list of Standard devices in the group:

  Device: 008C [SELECTED]

SELECTING BCV devices associated with the group:

  Device: 00F4 [SELECTED]

PAIRING of Standard and BCV devices:

  Devices: 008C(S) - 00F4(B) [PAIRED]

STARTING a BCV 'ESTABLISH' operation.

The BCV 'ESTABLISH' operation SUCCEEDED.

'Full Establish' operation successfully initiated for the device list in device file '/bcv-mapping.txt'.



4.]  The state of the BCV copy operation can be confirmed by running "symmir query"


Dopey # symmir -sid 822 -f /bcv-mapping.txt query


Device File Name      : /bcv-mapping.txt
Device's Symmetrix ID : 000290300822



     Standard Device                    BCV Device                  State
-------------------------- ------------------------------------- ------------
                    Inv.                                  Inv.
Logical        Sym  Tracks Logical              Sym       Tracks STD <=> BCV
-------------------------- ------------------------------------- ------------

N/A            008C      0 N/A                  00F4       21818 SyncInProg

Total              -------                               -------
  Track(s)               0                                 21818
  MB(s)                0.0                                1363.6



Legend:


(*): The paired BCV device is associated with this group.



5.]  The "-v" option can be specified with the "symmir query" operation to provide additional verbose output.



Dopey # symmir -sid 822 -v -f /bcv-mapping.txt query

SELECTING the list of Standard devices in the group:

  Device: 008C [SELECTED]

SELECTING BCV devices associated with the group:

  Device: 00F4 [SELECTED]

PAIRING of Standard and BCV devices:

  Devices: 008C(S) - 00F4(B) [PAIRED]


Device File Name      : /bcv-mapping.txt
Device's Symmetrix ID : 000290300822



     Standard Device                    BCV Device                  State
-------------------------- ------------------------------------- ------------
                    Inv.                                  Inv.
Logical        Sym  Tracks Logical              Sym       Tracks STD <=> BCV
-------------------------- ------------------------------------- ------------

N/A            008C      0 N/A                  00F4       15847 SyncInProg

Total              -------                               -------
  Track(s)               0                                 15847
  MB(s)                0.0                                 990.4



Legend:


(*): The paired BCV device is associated with this group.




6.] After some time, the BCV copy will be shown as " Synchronized ".


Dopey # symmir -sid 822 -f /bcv-mapping.txt query


Device File Name      : /bcv-mapping.txt
Device's Symmetrix ID : 000290300822



     Standard Device                    BCV Device                  State
-------------------------- ------------------------------------- ------------
                    Inv.                                  Inv.
Logical        Sym  Tracks Logical              Sym       Tracks STD <=> BCV
-------------------------- ------------------------------------- ------------

N/A            008C      0 N/A                  00F4           0 Synchronized

Total              -------                               -------
  Track(s)               0                                     0
  MB(s)                0.0                                   0.0



Legend:


(*): The paired BCV device is associated with this group.



7.] The extended attribute content reported by VxVM CLI command "vxdisk -e list" can be refreshed by running "vxdisk scandisks"


Dopey # vxdisk scandisks

Dopey # vxdisk -e -o alldgs list
DEVICE       TYPE           DISK        GROUP        STATUS               OS_NATIVE_NAME   ATTR
emc0_00f4    auto           -            -           error                c1t5006048C5368E5A0d281s2 bcv-nr    <<<< BCV lun in a Not-Ready (NR) state
emc0_00f5    auto:cdsdisk   -            -           online               c1t5006048C5368E580d275s2 bcv
emc0_008c    auto:cdsdisk   r1-008C      DopeyDg     online               c1t5006048C5368E580d266s2 mirror  <<< SRDF lun is an "established" state with the BCV lun "emc0_00f4"
emc0_008d    auto:cdsdisk   r1-008D      DopeyDg     online               c1t5006048C5368E5A0d223s2 srdf-r1
emc0_008e    auto:cdsdisk   r1-008E      DopeyDg     online               c1t5006048C5368E5A0d229s2 srdf-r1
emc0_008f    auto:cdsdisk   r1-008f      DopeyDg     online               c1t5006048C5368E580d269s2 srdf-r1


Note: The EMC SRDF source lun "emc0_008c" will be shown in a "mirror" state by "vxdisk -e list", whilst established with the EMC BCV target lun "emc0_00f4".

The EMC BCV VxVM related diskgroup image cannot be imported until the BCV state has been "split". The BCV lun is in a Not-Ready (NR) state until split.


Process complete.

BCV vs SymClone


EMC provides the ability to create cloned copies of data simultaneously on multiple target devices from a single source device. The data is available to the same (local) or target host instantly.

Note: You can copy data from a single source device to as many as sixteen target devices.

A source device can be either a Symmetrix standard (std) device or a BCV device. The target device is a Symmetrix clone that contains an exact copy of the source device.
The BCV lun is an EMC Symmetrix device with special attributes created when the Symmetrix is configured. It can function either as an additional mirror to an existing Symmetrix device or as an independent device.

Establishing BCV devices as mirror images of active production data, allows multiple simultaneous business continuance tasks to be performed in parallel. The principal (source) device, known as the standard (std) device, remains online for regular Symmetrix operations on the original production server.

Each BCV is unique, making it accessible to the production server, or a separate backup/disaster recovery (DR) server. 

The EMC symmir command forms an relationship between the std and BCV device when placed in an "established" state.
As a mirror of a standard device, the relationship is known as a BCV pair. The BCV device is temporarily inaccessible to its host until the BCV pair is "split".

A SymClone (clone) can be either an EMC Symmetrix standard (std) device, or an EMC BCV device, that is to be the clone copy (target device) of another EMC Symmetrix device. Unlike a BCV mirror copy, which must be completely synchronized with its source, and then split to access the data, the clone copy activation functionality makes the cloned disk image (data) immediately accessible to its host, even whilst copying is occurring in the background. The EMC symclone commands are used to create and activate a source/target clone pair.