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MARS FAQ :


Why do I need an automated file reloader?

    Manual analysis and initiation of file reloads can be done to keep your key-sequenced files healthy. However, different files degrade at different rates and some file access times are more critical than others. Each file or set of files may thus need to be reloaded according to different criteria, requiring work on your part and increasing the chance of errors.

    MARS allows you to set up your requirements once, then performs its work on an ongoing basis without the need for further intervention from you.

How can I justify the cost of MARS to my management?

    MARS will save you time by automatically maintaining the health of your application databases.

What makes MARS better than other products on the market?

    MARS is the only product of its kind on the market.

How much overhead does MARS take?

    When MARS is not actively reviewing files for possible reload there is no impact of CPU usage. When it is actively examining files, it uses a few percent of a CPU's cycles (less than 10 %).

    In addition to running MARS at a low priority to prevent contention with on-line applications, you may restrict MARS online reloads to certain CPUs and to a given time period.

How long does it take MARS to determine which files need to be reloaded?

    There are two factors that will determine how long this will take.

    The first factor is the number of files that are to be examined. You can specify that a given set of files will be checked at a given interval, so the completion time would only include files to be reviewed on that day. Within that set of files, which MARS reviews at a rate of about 600 per minute, the files that will be sampled for disorder and slack are processed at a rate of about 60 per minute.

    The second factor is system activity. If the system is very busy, MARS will be allocated fewer CPU cycles, so it will take longer to run. You can ensure that MARS processing takes place during relatively idle periods by specifying off-peak times for MARS activities.

What does MARS check for to determine whether a reload is required?

    MARS selects files for reload that show:
  • Excessive index levels, which impacts keyed record access.
  • Excessive disorder, which impacts sequential record access.
  • Excessive slack, which wastes disc space and can increase index levels.
  • Unreclaimed data due to SQL operations on the file.
Reloading files can consume a lot of system resources. Can they be scheduled to run at off-peak times?

    Yes. MARS defines a "processing window" during which it performs both file selection and reload tasks. Reloads are not started until the window is open and may be configured to run to completion or to be suspended when the window closes, to be continued the next day.
Is there anything else that can be done to minimize the impact of file reloads?

    As well as the NSK priority of the online reload process, you can allow only a given number of simultaneous reloads to be run. These reloads may also be segregated to a subset of your system's CPUs.




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Last Modified 1 February 2013.