taylor3

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T

taylor3

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July 27th, 2007 11:00

BCV and Symm Device group question

Hi all.
I know I can have multiple bcvs per standard device.

I currently have the following setup.
Host A has a standard dev dev001, and host B has bcv bcv001.
Both devices are in dev group HostA_B_BCV

If I want to associate another BCV to dev001, that will be mounted on host C my question is, can I create another device group that has dev001 and bcv002?

Or can I only have one device group that has dev001 and bcv001 and bcv002?

Thanks,
Taylor
  • munish2

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    Posted August 21st, 2007 11:00

    the pairing information of the devices resides in the symmetrix global memory. it is quite possible that the bcv device had been used with any other device in pairing relationship before.

    Any points for me ;-)

    Cheers !!
    Munish
  • dynamox

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    Posted July 27th, 2007 12:00

    i am afraid not ..a device can only be a member of one device group on a particular host. You could still put multiple BCVs in the device group but in your scripts you would need to specifically mention which BCV you want to manipulate, or you could use device files instead of device groups.
  • taylor3

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    Posted July 27th, 2007 12:00

    Thanks, can you give me a quick example of how I would use device files?
  • dynamox

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    Posted July 27th, 2007 13:00

    here is an excerpt from TimeFinder documentation:

    Device file 
     
    The device file (-file) option directs the specified operation in the symmir command
    to a device file. The device file contains device pairs (SymDevnames) listing a pair per
    each line (the standard first, a space, and the BCV last within each line entry). Device
    files can include comment lines that begin with the pound sign (#). The following
    example illustrates the file format, which specifies three device pairs:
     
    00A1 0103
    00A2 0104
    #00A3 0105 (To be reinstalled later)
    00B1 0106
     
    When you use this option, you must specify a target Symmetrix ID or set
    environment variable SYMCLI_SID. These options allow you to operate on
    Symmetrix arrays and remote BCV pairs beyond the first SRDF multi-hop.
    


    symmir -file -sid 056 establish
  • taylor3

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    Posted July 27th, 2007 13:00

    I think I have it. So if I wanted to split 2 bcvs associated with the same standard dev at different times, I could create two device files.

    So for standard dev 0001 and BCVs 0050 and 0060 I could have

    file
    0001 0050

    file
    0001 0060

    and then run my query/split/establish commands by issuing:
    symmir -file -sid 056 establish/query/split?

    Is that correct?
    Thanks,
    Taylor
  • dynamox

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    Posted July 27th, 2007 13:00

    you got it.
  • taylor3

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    Posted July 27th, 2007 13:00

    I think I have it. So if I wanted to split 2 bcvs associated with the same standard dev at different times, I could create two device files.

    So for standard dev 0001 and BCVs 0050 and 0060 I could have

    file1.txt
    0001 0050

    file2.txt
    0001 0060

    and then run my query/split/establish commands by issuing:
    symmir -file -sid 056 establish/query/split?

    Is that correct?
    Thanks,
    Taylor
  • xe2sdc

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    Posted July 30th, 2007 02:00

    Hi taylor.

    Since S.E. 6.3 there is a new "symld" functionality available .. It's called "symld copy" and allows you to copy a STD device from a DG to another one. "Copying" means that a single STD can live in two different DGs. Have a look at primus solution emc149642 if you want further details.

    To use this feature you need to enable a variable into your /var/symapi/config/options file. The option is called "SYMAPI_ALLOW_DEV_IN_MULT_GRPS" and you need to put a line in the file with

    SYMAPI_ALLOW_DEV_IN_MULT_GRPS = ENABLE

    Enabling this variable allows you to have 2 different dgs with the same STD and different BCVs as follows.

    rss4/root> symdg show host_a_c

    Group Name: host_a_c

    Group Type : REGULAR
    Device Group in GNS : Yes
    Valid : Yes
    Symmetrix ID : 000287890xxx
    Group Creation Time : Mon Jul 30 11:01:52 2007
    Vendor ID : EMC Corp
    Application ID : SYMCLI

    Number of STD Devices in Group : 1
    Number of Associated GK's : 0
    Number of Locally-associated BCV's : 1
    Number of Locally-associated VDEV's : 0
    Number of Locally-associated TGT's : 0
    Number of Remotely-associated VDEV's(STD RDF): 0
    Number of Remotely-associated BCV's (STD RDF): 0
    Number of Remotely-associated TGT's(TGT RDF) : 0
    Number of Remotely-associated BCV's (BCV RDF): 0
    Number of Remotely-assoc'd RBCV's (RBCV RDF) : 0

    Standard (STD) Devices (1):
    {
    --------------------------------------------------------------------
    Sym Cap
    LdevName PdevName Dev Att. Sts (MB)
    --------------------------------------------------------------------
    DEV001 N/A 18F0 RW 8723
    }

    BCV Devices Locally-associated (1):
    {
    --------------------------------------------------------------------
    Sym Cap
    LdevName PdevName Dev Att. Sts (MB)
    --------------------------------------------------------------------
    BCV001 N/A 1527 RW 8723
    }

    rss4/root> symdg show host_a_b

    Group Name: host_a_b

    Group Type : REGULAR
    Device Group in GNS : Yes
    Valid : Yes
    Symmetrix ID : 000287890xxx
    Group Creation Time : Mon Jul 30 11:01:50 2007
    Vendor ID : EMC Corp
    Application ID : SYMCLI

    Number of STD Devices in Group : 1
    Number of Associated GK's : 0
    Number of Locally-associated BCV's : 1
    Number of Locally-associated VDEV's : 0
    Number of Locally-associated TGT's : 0
    Number of Remotely-associated VDEV's(STD RDF): 0
    Number of Remotely-associated BCV's (STD RDF): 0
    Number of Remotely-associated TGT's(TGT RDF) : 0
    Number of Remotely-associated BCV's (BCV RDF): 0
    Number of Remotely-assoc'd RBCV's (RBCV RDF) : 0

    Standard (STD) Devices (1):
    {
    --------------------------------------------------------------------
    Sym Cap
    LdevName PdevName Dev Att. Sts (MB)
    --------------------------------------------------------------------
    DEV001 N/A 18F0 RW 8723
    }

    BCV Devices Locally-associated (1):
    {
    --------------------------------------------------------------------
    Sym Cap
    LdevName PdevName Dev Att. Sts (MB)
    --------------------------------------------------------------------
    BCV001 N/A 1526 RW 8723
    }
  • dynamox

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    Posted July 30th, 2007 06:00

    Stefano,

    awesome man ..thank you for explaining this ..i had no clue you could do that now, i like the fact that you have to explicitly copy devices from an existing group and not simply add an existing device to another device group ..that would be a potential problem to happen. Do you know if you can add VDEVS to multiple groups as well ?
  • xe2sdc

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    Posted July 30th, 2007 06:00

    Dynamox .. I'm awesome just like a storm ;-) ... It depends on your taste :-P

    In fact you can add the same device to two different DGs given that you have already enabled the variable into the "option" file. The "copy" functionality is an usefull thing that you can use if you already have a DG. No potential problems since you need to enable the variable in the options file before making something "dangerous".

    I really don't know if it's possible to add the same vdev to different DGs .. I think that you can apply the same rule as per BCVs .. so -my speculation- the answer is NO .. But I'd be glad to be wrong :-)