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What is a VOB?
The term VOB stands for Versioned Object Base. A versioned object is a file or directory. They are objects for which ClearCase keeps track of versions. a VOB is a database of such objects. In the simplest terms, a VOB is a container that holds elements.

There are typically a thousand or more elements in a given VOB. These may correspond to one product or a set of related products. Or, a VOB may contain just a portion of a very large product or system.

VOBs can manage any kind of file, including source code, documentation, binaries, executables, libraries, etc. VOBs can also managed files derived from source files, and these are called derived objects. ClearCase provides special handling and tracks additional information about derived objects.

How You Use VOBs
A VOB appears to you as a directory structure containing files. Your company might have a dozen or more VOBs, but you might work in only a few of them. When you want to work with the files and directories in a VOB you will change directories into that VOB just as if it were a standard directory structure.

In fact, VOBs behave like separate filesystems. A VOB must be mounted on any computer you want to use to work with the VOB's files. You may not have all the VOBs mounted on your computer. If your computer reboots it is possible that the vobs will not be mounted. You can run a simple command to remount them. The command has no effect if they are already mounted:

Mount All VOBs
cleartool mount -all

NT Note: You may also mount a VOB from the File Manager: ClearCase->Mount VOB...

This will summon a VOB Tag browser to let you choose the VOB to mount.

Each VOB appears in the filesystem at a different location, but they may all appear within the same directory (or logical drive on NT).

For example, if you had separate VOBs to store products called flint and stone they might appear as:
/vobs/flint
/vobs/stone

NT Note: On NT these would appear as:
\flint
\stone

Some commands also accept a list of one or more VOBs to restrict their operation. For example:

Show all checkouts in the flint and stone VOBs:
cleartool lscheckout -all /vobs/flint /vobs/stone

Show all checkouts in all VOBs for the current view:
cleartool lscheckout -avobs


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