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Properly using SAN storage for VOB database access while using a NAS filer for ClearCase client access

Question & Answer


Question

How can you properly configure IBM Rational ClearCase to use Storage Area Network (SAN) storage for a VOB database while using a Network Attached Storage (NAS) filer for ClearCase client access?

Cause


To utilize the fastest interface possible for VOB database access from the VOB Server host combined with the fastest interface possible for client access within a ClearCase Client environment, the following details how to use both SAN and NAS storage properly.

Answer

When performing this storage change, copying the sdft, cdft and ddft directories is highly recommended. This configuration and note assumes the VOB is presently stored on SAN attached storage. Thus, the SAN attached storage is being exported from the VOB server to the ClearCase clients through NFS.

After the configuration change, the NAS filer would be used for ClearCase Client access. This configuration, when using SAN attached for the VOB server database access and NAS filer storage for the Client side activity, will off-load NFS server export responsibilities from the VOB server and will leverage the NAS filer to handle the client-side NFS load.

Refer to the following documentation as a guideline before continuing with the steps below:

Moving an existing storage pool to another disk


For instance:

      • The existing SAN attached VOB storage mount point on the VOB server is:

           /ccstg/vobs
      • A test VOB is created, and below is the path including the db directory:

          /ccstg/vobs/test.vbs

           Tag:  /vob/test
      • The SAN storage path /ccstg/vobs is presently being NFS exported by the VOB server for the clients to access the pools
      • The NAS storage that will be used is as follows, including the test VOB's path:

          /net/nas-filer/ccstg/vobs/test.vbs


Given the above, the following would be the steps to migrate the sdft, cdft, and ddft pools to NAS storage:

Important Note: Prior to making any changes, verify that a proper and full backup of the VOB has been complete prior to the migration of the pools. The backup strategy may have to be modified depending on how the database and pools are being backed up.

  1. Lock all VOB(s) being affected by the storage change

  2. Stop ClearCase

  3. Verify that all ClearCase processes have terminated

  4. Make a new export for the VOB pools on the NAS filer following the recommended steps within the respective vendor white papers for ClearCase exports from filer storage:

  5. Mount the new NAS storage export onto the VOB server. Note that this will be the gpath used by the ClearCase clients as well as View servers and, thus, should be accessible by each ClearCase client and View server within the environment that will access these VOBs. Using the automounter may simplify the configuration greatly.

  6. On the new NAS storage, create a new test.vbs directory including the empty s, c and d directories as the vobadm. We will use /ccstg/vobs/test.vbs as an example.

    cd /net/nas-filer/ccstg/vobs/
    mkdir test.vbs
    mkdir test.vbs/s test.vbs/c test.vbs/d
    chmod -R 755 test.vbs

  7. While the pwd is still within /net/nas-filer/ccstg/vobs, copy the s, c and d directories from the SAN storage to the NAS storage:

    cp -R -p /ccstg/vobs/test.vbs/s/* test.vbs/s
    cp -R -p /ccstg/vobs/test.vbs/c/* test.vbs/c
    cp -R -p /ccstg/vobs/test.vbs/d/* test.vbs/d

  8. cd into the SAN VOB storage and move the existing sdft, cdft and ddft pools to a different name:

    cd /ccstg/vobs/test.vbs
    mv test.vbs/s/sdft test.vbs/s/sdft_OLD
    mv test.vbs/c/cdft test.vbs/c/cdft_OLD
    mv test.vbs/d/ddft test.vbs/d/ddft_OLD

  9. While the pwd is still within the SAN VOB Storage root of the test.vbs directory (as in 8. above), make the following symlinks:

    ln -s /net/nas-filer/ccstg/vobs/test.vbs/s/sdft test.vbs/s/sdft
    ln -s /net/nas-filer/ccstg/vobs/test.vbs/c/cdft test.vbs/c/cdft
    ln -s /net/nas-filer/ccstg/vobs/test.vbs/d/ddft test.vbs/d/ddft

  10. cd into the NAS storage and into the root of the .vbs directory and copy the replica_uuid and vob_oid from the SAN storage:

     cd /net/nas-filer/ccstg/vobs/test.vbs
     cp -p /ccstg/vobs/test.vbs/replica_uuid .
    cp -p /ccstg/vobs/test.vbs/vob_oid .

  11. Re-register and Re-tag the VOB:

    cleartool rmtag -vob -all /vob/test
     cleartool unregister -vob /ccstg/vobs/test.vbs
    cleartool register -vob -host vobserver -hpath /ccstg/vobs/test.vbs /net/nas-filer/ccstg/vobs/test.vbs
    cleartool mktag -vob -tag /vob/test -host vobserver -hpath /ccstg/vobs/test.vbs -gpath /net/nas-filer/ccstg/vobs/test.vbs /net/nas-filer/ccstg/vobs/test.vbs

  12. Start ClearCase and verify the VOB above can be described and unlocked, and that elements and versions can be accessed from a VOB/View context:

    cleartool describe -long vob:/vob/test
     cleartool unlock vob:/vob/test

  13. Once the VOB pools have been verified to have been successfully moved to the NAS filer and ClearCase clients are able to use the storage, cleanup of the SAN pools renamed to sdft_OLD, cdft_OLD and ddft_OLD can be done at this time.

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Document Information

Modified date:
16 June 2018

UID

swg21498931

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