25.11 Registry Guidelines

Following are some general tips, warnings, and guidelines regarding ClearCase storage registry administration:

• You cannot access a VOB or view (even to remove it) unless it has both a tag registry entry and an object registry entry. Use the ClearCase Administration console or lsvob or lsview to see whether the tag is missing (no listing at all) or the object entry is missing (no storage paths appear in the -long output).

If you cannot access a VOB or view, first make sure it has a tag. If it does not appear in the output of an lsvob or lsview command, it has no tag. Create one with the ClearCase Administration console or mktag.

If it has a tag, list the tag with the ClearCase Administration console or lsvob -long or lsview -long. If the output includes incorrect pathnames (identical local and global pathnames usually mean trouble), you can try to re-register the object (with mktag and/or register) to supply correct pathnames. If everything looks correct and you still cannot access the VOB, contact Technical Support.

• When using UNIX symbolic links, make sure the links can be resolved by all hosts that need to access the VOB. For example:

/usr/vobs -> /usr/vobstore <--- wrong

When this link is resolved on a client host, the full pathname /usr/vobstore references the /usr directory on the client host.

/usr/vobs -> ../vobstore <--- right

When this link is resolved on a client host, the relative pathname ../vobstore references a location on the VOB host.

Similarly, beware of full pathnames in VOB symbolic links that point to locations in other VOBs.

• On UNIX VOB and view hosts, watch out for links to unexported disk partitions. If you cannot access a VOB and suspect a faulty registry pathname, follow the registered global pathname to the storage host and pwd to see where you are. Make sure a link does not point to a location in an unexported partition. For example:

/usr/vobs -> ../vobstore

This link causes failures if the location /usr/vobstore is in another partition that is not exported.

• Don't try to rename a tag; replace it using mktag -replace.

• Don't use operating system utilities such as rm, rmdir, or GUIs such as Windows Explorer to delete a VOB or view a storage directory; this doesn't clean up the registry entries.

• Don't delete tags before deleting the storage directory; let rmvob or rmview delete tags for you.

• When creating a VOB or view, creating a VOB-tag or view-tag, registering or unregistering a storage directory, or reformatting a VOB-especially when using the -host -hpath -gpath options together-execute the command on the host where the VOB or view storage directory resides. This enables ClearCase to validate some pathnames, which it cannot do when the command is executed from a remote host.

• Use the rgy_check utility to diagnose problems or for periodic cleanup of obsolete or stranded registry entries.

Multiple Registries

We do not recommend configuring multiple registry hosts to serve clients in the same network region. A network configuration that includes a separate registry server for each region can be used if organizational or other concerns require it. However, maintaining multiple registry servers can significantly increase administrative workload. Registry access does not usually create significant server load, and any benefit that might be achieved through registry server load-balancing will most likely be outweighed by the costs of maintaining registry data on multiple registry hosts.

If you decide to maintain multiple registry hosts, keep the following points in mind:

• If you want clients in separate registries to share one or more VOBs or views, create all shared VOBs and views in the same region before registering them in additional registries.

• When registering a VOB or view in an additional registry, run the mktag and register commands from a host assigned to that registry.

• The rgy_check, rgy_switchover, and Region Synchronizer commands cannot be used effectively in a multiple registry installation.

• Although you can create regions with the same name in different registries, this is likely to cause confusion and is not recommended.