HP 3000 Manuals HP 3000 Manuals
Guidelines for Maintaining the Database
To optimize the performance and integrity of the database, you can
implement a regular maintenance schedule. For example:
1. Establish baseline statistics for your database against which
future statistics can be compared. To do this, use the CHECK BASE
command with the QUICK parameter and archive the resulting output.
Note that your database should be performing optimally and should
not contain structural problems when you establish your baseline.
2. Periodically check the database and compare the output to the
original baseline statistics. To do this, use the CHECK BASE
command with the QUICK parameter.
3. Correct problems that are detected. To do this, use the FIX
command to correct structural problems in both master and detail
data sets. Use the REPACK command with the new blocking factor,
if necessary, to correct disk space utilization of detail data
sets.
Regularly checking and fixing the database can prevent the following
problems:
* Large clusters in master data sets.
* Poor packing on heavily used chains.
* Large gaps caused by deleted records in detail data sets.
Optionally, you can use the FIX PATH or FIX BASE commands only. The FIX
commands invoke the checking process as explained in the following
section.
How the FIX Commands Operate
The FIX PATH and FIX BASE commands operate as follows:
1. A CHECK BASE QUICK (serial read only) is performed. If no
problems are found, the FIX command stops processing and a message
is returned informing you that no problems are detected. If
problems are found, then the next step occurs.
2. To further isolate any problems located by CHECK BASE QUICK, a
standard CHECK PATH (serial read followed by a chained read) is
performed for each path that has a consistency problem.
Corrections are applied to the problems, and messages are returned
informing you where the corrections occurred.
The REPACK, CHECK, and FIX commands, along with the QUICK option, are
discussed in detail later in this chapter.
NOTE If a correct backup of the root file does not exist, you must
manually correct root file and file structure errors.