Technical Bulletin #41

TO: All Sites Using ClearCase MultiSite
FROM: Customer Support
DATE: 6/19/01
SUBJECT: Technical Bulletin Number 41

Error in Moving a VOB Procedure in Administering ClearCase

The Release 4.1 Administering ClearCase manual contains an error in the procedure for moving a VOB on Windows NT. If you use this procedure to move a replicated VOB, oplog divergence can occur in the VOB family. If divergence occurs, it will be detected during the next synchronization from the moved VOB.

The incorrect information appears in Section 14.3, Moving a VOB on Windows NT, which instructs you to unlock the VOB (Step 8) before unregistering the VOB at its old location (Step 9). The correct procedure is to unregister the VOB at its old location, register it at its new location, and then unlock the VOB.

The following section describes the correct procedure for moving a VOB on Windows NT. For more information about moving a VOB between domains or moving a VOB when there are SID dependencies, see the whitepaper ClearCase and Active Directory, which is available on the Rational Web site.

This section explains how to move a VOB to another disk partition on the same Windows NT host or to a new Windows NT host.

WARNING: When moving a VOB or view storage directory, use copy or backup software that preserves ownership and access control information.

For clarity, this section uses an example:

• The current location of the VOB storage directory to be moved is c:\vobstore\libpub.vbs, on a host named sol.
• The VOB is mounted by client hosts at \libpub.
• The new location for the VOB storage directory is c:\vobstore2\libpub.vbs. The example includes these cases:
  • The new location is also on sol.
  • The new location is on another host, named ccsvr04.

Perform this procedure as the VOB owner:

1. Deactivate the VOB. Issue this command on each host where the VOB is currently active:
   

   cleartool umount \libpub
   

   NOTE: It may not be practical to unmount the VOB from all hosts. In this case, the VOB lock to be applied in Step 4 ought to prevent unintended VOB access.

2. (If applicable) Disable VOB snapshots on the current host. If VOB database snapshots are enabled on the VOB, disable them with the following command:
   

   vob_snapshot_setup rmparam \libpub
   

3. Back up the VOB storage directory. Use the procedures described in the chapter Backing Up and Restoring VOBs.
   
4. Lock the VOB.
   

   cleartool lock vob:\libpub
   Locked versioned object base "\libpub".
   

5. Stop ClearCase. On the host where the VOB storage directory resides, open Control Panel. In the ClearCase program, click the Services Startup tab and click Stop ClearCase.
   
6. Copy the VOB storage directory. Make sure that the target location exists and is writable. Then, copy the entire VOB storage directory tree to the new location.
   

   NOTE: Do not use Windows Explorer to copy the VOB storage directory, because ownership information may be changed incorrectly. The examples below use the ccopy command; although ccopy copies all of the ownership information required by ClearCase, it does not copy the full security descriptor of an object. Use of ccopy effectively grants the user who executes the command full access to the copied object. If you need to have all security descriptor information copied, use a copy utility that preserves this information (for example, the scopy command from the Windows NT Resource Kit):

   scopy libpub.vbs w: /o /s

   • To copy the VOB storage directory to the same host:

     C:\vobstore> ccase-home-dir\etc\utils\ccopy libpub.vbs \vobstore2\libpub.vbs

   • To copy the VOB storage directory to a different host:

   C:\> cd \vobstore

   C:\vobstore> net use w: \\ccsrv04\vobstore2

   C:\vobstore> ccase-home-dir\etc\utils\ccopy libpub.vbs w:\libpub.vbs

   
   
7. Restart ClearCase. In Control Panel on the host where the VOB storage directory resides, open the ClearCase program; click Start ClearCase on the Services Startup tab.
   
8. Ensure that the old VOB cannot be reactivated. Remove it from the ClearCase storage registries. In the ClearCase Administration Console, you can use the VOB Tags node for the tag's regions to remove these VOB-tags, and you can use the VOB Objects subnode of the ClearCase Registry node to remove the VOB object. You can also use these commands:
   

   cleartool unregister -vob \\sol\vobstore\libpub.vbs
   cleartool rmtag -vob -all \libpub
   

9. Register the VOB at its new location. When you move a public VOB, you must enter the registry password. In the ClearCase Administration Console, you can use the VOB Tags node for the tag's regions to create VOB-tags, and you can use the VOB Objects subnode of the ClearCase Registry node to create a VOB object entry. You can also use these commands:
   

   cleartool register -vob \\ccsvr04\vobstore2\libpub.vbs
   cleartool mktag -vob -public -tag \libpub \\ccsvr04\vobstore2\libpub.vbs
   Vob tag registry password:
   

   NOTE: If you are registering a Unified Change Management Process VOB, you must supply the -ucmproject option to the register command.

   If your network has several network regions, see Ensuring Global Access to the VOB--Special Cases for UNIX for a discussion of adjustments and additional registry entries you may need to make.

10. Unlock the VOB.
    

    cleartool unlock vob:\libpub
    Unlocked versioned object base "\libpub".
    

11. Reactivate the VOB. On all client hosts:
    

    cleartool umount \libpub
    (if not already done)
    cleartool mount \libpub
    

12. Delete the old VOB storage directory. If you did not overwrite the existing VOB storage directory, delete it after you verify that the VOB can be accessed at its new location.
    
13. (If applicable) Enable VOB snapshots on the new host. If you want to enable VOB database snapshots on the new VOB host, run the vob_snapshot_setup command and supply the appropriate parameters.
    

If you have any questions regarding the situations discussed in this Technical Bulletin, please contact Rational Customer Support via telephone, fax, or electronic mail as described below. For information regarding support hours, languages spoken, or other support information, click the Technical Support link on the Rational Web site at www.rational.com.

Technical Bulletin #41 - 6/19/01