3.3

4 Database Management
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The -d instructs dbvisit to print a period each time it visits a new queue and a colon
for every 1,000 stories in a queue. After you have done a few cleanups, you can
judge how far dbvisit has progressed by the number of periods it has printed. When
you run dbvisit, it begins with the root file structure and then examines the entire
directory. As it inspects the root files and then the directory, dbvisit prints messages
indicating its progress.
n
Running dbvisit on all servers instead of just the master computer is an option, performed by
typing
dbvisit -dr . The 'r' indicates read-only mode, and it can run while the read-write
dbvisit is running on the master server. The read-only dbvisit cannot be started until the
read-write dbvisit reaches the 'traversing directory' phase. After dbvisit runs on all
computers, the output can be compared to verify the integrity of the mirror.
The dbvisit process has four main phases:
- Visiting the “root” blocks
- Traversing the directory and queue structures
- Visiting the stories
- Rebuilding the free list and fixing link counts
3. When the system prompts you with Rebuild the free list (y/n)?, do the following:
a. Ensure dbvisit has completed on all servers (otherwise error messages may appear).
b. Type
y only if there are no error messages.
If there are any error messages among the periods printed after traversing directory,
do not rebuild the free list and contact Avid immediately for instructions.
Otherwise, type
n to skip rebuild of the free list.
Skipping rebuild of the free list retains the old free list. While this means that
unreferenced blocks are not collected back to the free list, you can add them to the
free list later by performing another dbvisit.
n
If there are link count discrepancies, the system will list them. Such advisory messages about
high and low link counts are not errors, however, you will be prompted to correct them.
c
Rebuilding a free list without first fixing the errors seriously corrupts your database.
4. If you do not see any error messages, select the master computer (typically server A)
and type
y .
In addition to spotting errors in the database structure, dbvisit collects any unreferenced
blocks and puts them on the free list. Unreferenced blocks are not used by any story and
are not a part of the free list. They are stray blocks that cannot be used until they are put
on the free list.