Migrating to thin provisioning

Article:HOWTO59587  |  Created: 2011-10-12  |  Updated: 2011-10-12  |  Article URL http://www.symantec.com/docs/HOWTO59587
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Migrating to thin provisioning

The SmartMove™ feature enables migration from traditional LUNs to thinly provisioned LUNs, removing unused space in the process.

See the Veritas Volume Manager Administrator's Guide for more information on SmartMove and Thin Provisioning.

To migrate to thin provisioning

  1. Check if the SmartMove Feature is enabled.

    See Displaying the SmartMove configuration.

    See Changing the SmartMove configuration.

  2. Add the new, thin LUNs to the existing disk group. Enter the following commands:

    # vxdisksetup -i da_name
    # vxdg -g datadg adddisk da_name

    where da_name is the disk access name in VxVM.

  3. To identify LUNs with the thinonly or thinrclm attributes, enter:

    # vxdisk -o thin list
  4. Add the new, thin LUNs as a new plex to the volume.

    NOTE: The VxFS file system must be mounted to get the benefits of the SmartMove feature.

    The following methods are available to add the LUNs:

    • Use the default settings for the vxassist command:

      # vxassist -g datadg mirror datavol da_name
    • Specify the vxassist command options for faster completion. The -b option copies blocks in the background. The following command has more I/O affect:

      # vxassist -b -oiosize=1m -t thinmig -g datadg mirror \
        datavol da_name
      # vxtask monitor thinmig
    • Specify the vxassist command options for minimal effect. The following command takes longer to complete:

      # vxassist -oslow -g datadg mirror datavol da_name
  5. Optionally, test the performance of the new LUNs before removing the old LUNs.

    To test the performance, use the following steps:

    • Determine which plex corresponds to the thin LUNs:

      # vxprint -g datadg
      TY NAME         	     ASSOC   	       KSTATE   LENGTH     PLOFFS  STATE     TUTIL0 PUTIL0
      dg datadg       	     datadg      	   -        -          -       -         -       -
      dm THINARRAY0_02      THINARRAY0_02   -      	 83886080   -       -         -       -
      dm STDARRAY1_01	      STDARRAY1_01    -  	     41943040   -       -OHOTUSE  -       -
      
      v  datavol      	     fsgen        	  ENABLED 	41943040   -       ACTIVE    -       -
      pl datavol-01   	     datavol      	  ENABLED 	41943040   -       ACTIVE    -       -
      sd STDARRAY1_01-01    datavol-01   	  ENABLED 	41943040   0       -         -       -
      pl datavol-02   	     datavol      	  ENABLED 	41943040   -       ACTIVE    -       -
      sd THINARRAY0_02-01   datavol-02   	  ENABLED 	41943040   0       -         -       -

      The above output indicates that the thin LUN corresponds to plex datavol-02.

    • Direct all reads to come from those LUNs:

      # vxvol -g datadg rdpol prefer datavol datavol-02
  6. Remove the original non-thin LUNs.

    Note:

    The ! character is a special character in some shells. This example shows how to escape it in a bash shell.

    # vxassist -g datadg remove mirror datavol \!STDARRAY1_01
    # vxdg -g datadg rmdisk STDARRAY1_01
    # vxdisk rm STDARRAY1_01
  7. Grow the file system and volume to use all of the larger thin LUN:

    # vxresize -g datadg -x datavol 40g da_name

See About using SmartMove to migrate to Thin Storage


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Article URL http://www.symantec.com/docs/HOWTO59587


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