Scrubber utilities remove unneeded data from VOB databases. You
can control how often they run and what data they remove.
VOB storage must be managed to control growth. Two utilities, the
scrubber and
the
vob_scrubber, help manage the growth of VOB storage.
Table 1 describes the function
of each of these utilities.
Table 1. Default scrubber and vob_scrubber actions| Program |
Item removed (default) |
How removed item is created |
|---|
| scrubber |
Cleartext containers that have not been referenced for
more than 96 hours |
Any command that accesses a version of an artifact in a
VOB |
| Derived objects that have not been referenced for more
than 96 hours |
clearmake, omake, clearaudit (dynamic
views only) |
| vob_scrubber |
Certain event records (see vob_scrubber reference
page for details) |
Any command that creates or modifies elements, versions,
or other metadata. |
| Certain oplog entries (see vob_scrubber reference
page for details) |
Any modification of data or metadata in a replicated VOB. |
Both utilities run on a default schedule with default parameters on any
computer that hosts one or more VOBs. You might need to reconfigure scrubbing
parameters and schedules if the default ones are not appropriate.
Scrubbing VOB storage pools
Several
basic rules the govern operations of the
scrubber:
- Cleartext pools are scrubbed to control their size. These pools are essentially
caches; scrubbing unneeded data containers in a cleartext pool has little
or no effect on performance.
- Derived object pools are scrubbed to delete DO data containers that are
no longer being used by any view. Scrubbing also removes the corresponding
derived objects from the VOB database.
- Source pools are never scrubbed.
- The scrubber does not delete a container until all of its handles are
closed. You can ensure that a container has no open handles by unmounting
the VOB in which the container is stored from all hosts.
In the default configuration, the scrubber runs
nightly as part of the Daily VOB Pool Scrubbing task. You can also run it
manually.
Each derived object and cleartext storage pool has its own
scrubbing parameters, which control how the scrubber processes
that pool. To change the way VOB storage pools are scrubbed, you can change
the scrubbing parameters for an individual pool by using the Rational® ClearCase®Administration
Console or a mkpool –update command. For
more information, see Adjusting default scrubbing parameters.
Scrubbing VOB databases
Almost
every change to a versioned artifact is recorded in the VOB database as an
event record. Some event records have permanent value, such as those for the
creation of elements and versions. Others might not be useful to your organization
or might lose their value as time passes. (For example, you probably do not
care about the removal of an unneeded or obsolete version label.)
Each
VOB host has a scrubber configuration file,
ccase-home-dir\config\vob\vob_scrubber_params, which controls
vob_scrubber operation for all VOBs on
that host. If you need more control over scrubbing schedules, you can create
a scrubber parameters file for each VOB. This file is also named
vob_scrubber_params,
but it is located in the VOB storage directory. See the
vob_scrubber reference
page for more information.
Note: Deleting event records and other metadata
from the VOB database, using the vob_scrubber or any other
mechanism (rmver, rmelem, relocate,
and so on), increases the amount of free space in the database, but does not
reduce the disk space used by the VOB database. A regularly scrubbed VOB database
grows slowly and should not require further intervention to keep growth under
control. However, if you must occasionally force a reduction in the size of
a VOB database, scrub it, and then run the reformatvob command.