Description

This document attempts to explain the steps required to create a BCV image of a SRDF (R2) device when using Veritas Volume Manager and DMP.

Note: The SRDF (R2) lun is in a write-disabled 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 "emc1_0072" to BCV lun "emc1_00dc"


1.] The extended device attribute's can be reported by running "vxdisk -eo alldgs list".


Bashful # vxdisk -eo alldgs list
DEVICE       TYPE           DISK        GROUP        STATUS               OS_NATIVE_NAME   ATTR
emc1_00dc    auto:cdsdisk   -            -           eonline                c1t5006048C536979A0d80s2 bcv                    <<<< BCV image of "emc1_0072"
emc1_00dd    auto:cdsdisk   -            -           online               c1t5006048C536979A0d81s2 bcv
emc1_0072    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d65s2 srdf-r2    <<<< SRDF R2 lun. Write-Disabled
emc1_0073    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d66s2 srdf-r2
emc1_0074    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d67s2 srdf-r2
emc1_0075    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d68s2 srdf-r2


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
0072 00dc


The EMC SYMDEV reference in the first column is the source lun "0072", which relates to Veritas disk access (da) name "emc1_0072".
The EMC SYMDEV reference in the second column is the target lun "00DC" for the EMC BCV device, which relates to Veritas disk access (da) name "emc1_00dc".



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 " 000290301414 ", for which can be shortened to just three characters in length "414".

Bashful # vxdmpadm listenclosure all
ENCLR_NAME        ENCLR_TYPE     ENCLR_SNO      STATUS       ARRAY_TYPE     LUN_COUNT
===================================================================================
emc1              EMC            000290301414         CONNECTED    A/A        6


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


Bashful # symmir -sid 414 -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: 0072 [SELECTED]

SELECTING BCV devices associated with the group:

  Device: 00DC [SELECTED]

PAIRING of Standard and BCV devices:

  Devices: 0072(S) - 00DC(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"


Bashful # symmir -sid 414 -v -f  /bcv-mapping.txt query

SELECTING the list of Standard devices in the group:

  Device: 0072 [SELECTED]

SELECTING BCV devices associated with the group:

  Device: 00DC [SELECTED]

PAIRING of Standard and BCV devices:

  Devices: 0072(S) - 00DC(B) [PAIRED]


Device File Name      : /bcv-mapping.txt
Device's Symmetrix ID : 000290301414



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

N/A            0072      0 N/A                  00DC       27158 SyncInProg

Total              -------                               -------
  Track(s)               0                                 27158
  MB(s)                0.0                                1697.4



Legend:


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


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


Bashful # symmir -sid 414 -f  /bcv-mapping.txt query


Device File Name      : /bcv-mapping.txt
Device's Symmetrix ID : 000290301414



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

N/A            0072      0 N/A                  00DC           0 Synchronized

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



Legend:


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



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


Bashful # vxdisk scandisks

Bashful # vxdisk -eo alldgs list
DEVICE       TYPE           DISK        GROUP        STATUS               OS_NATIVE_NAME   ATTR
emc1_00dc    auto           -            -           error                c1t5006048C536979A0d80s2 bcv-nr    <<<< BCV lun in a Not-Ready (NR) state
emc1_00dd    auto:cdsdisk   -            -           online               c1t5006048C536979A0d81s2 bcv
emc1_0072    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d65s2 mirror   <<< SRDF lun is an "established" state with the BCV lun "emc1_00dc"
emc1_0073    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d66s2 srdf-r2
emc1_0074    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d67s2 srdf-r2
emc1_0075    auto:cdsdisk   -            (DopeyDg)   online               c1t5006048C536979A0d68s2 srdf-r2


Note: The EMC SRDF source lun "emc1_0072" will be shown in a "mirror" state by "vxdisk -e list", whilst established with the EMC BCV target lun "emc1_00dc".

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 v 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 a 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.