Determining Your Dump-to-Disk Needs

1. Estimate the size of the largest dump file.

2. Determine the number of dump files that you want to preallocate.

3. Determine the number of disk drives required to store all of your dump files and the AutoRestart/iX utilities.

Estimate size of largest dump file

Calculating the actual size of a system dump is difficult. The following variable factors contribute to the size of a dump:

To ensure that the size of the dump file that you create covers all possible cases, you must estimate the largest dump possible on your system. Two methods that can be used to estimate your system's largest possible dump size are as follows:

Use number of active jobs/sessions to estimate largest dump size

The following table shows the possible ranges of dump sizes, based on the number of active jobs and sessions on your system, and the size of your main memory.

	NOTE: Hewlett-Packard strongly recommends that you preallocate dump files using the high estimates, to ensure successful dumps to disk.

Table 2-1 Dump File Size Estimates

# Active Jobs/Sessions	Main Memory Size	Dump Size Low Estimate	Dump Size High Estimate
50	64 MB 96 MB 128 MB	94 MB 106 MB 119 MB	154 MB 166 MB 179 MB
100	64 MB 96 MB 128 MB	124 MB 136 MB 149 MB	244 MB 256 MB 269 MB
150	64 MB 96 MB 128 MB	154 MB 166 MB 179 MB	334 MB 346 MB 359 MB
200	64 MB 96 MB 128 MB	184 MB 196 MB 209 MB	424 MB 436 MB 449 MB
250	64 MB 96 MB 128 MB	214 MB 226 MB 239 MB	514 MB 526 MB 539 MB
300	64 MB 96 MB 128 MB	244 MB 256 MB 269 MB	604 MB 616 MB 629 MB

 

Use DTODSIZ utility to estimate largest dump size

If you have already installed AutoRestart/iX on your system, you can use the DTODSIZ utility to estimate dump size, based on system activity occurring when DTODSIZ is executed. The DTODSIZ utility can be run either interactively or from a job.

At the system prompt, enter:

:RUN DTODSIZ.HP36375.TELESUP

When DTODSIZ runs, it estimates the size of a dump that would occur at that time, and recommends the megabyte size required to hold that dump.

Following is an example of what DTODSIZ displays (in this example, the dump-to-disk feature is not yet configured):

Dump-to-Disk environment not set up on this system. *************************************************** * * Dump-to-Disk Dumpfile size check FAILED!- * * current Dumpfile size - 0 MB * * checkpoint estimate - 192 MB * * RECOMMENDATION: * * Increase Dumpfile size to: 230 MB * at earliest convenience using * BLDDUMP.HP36375.TELESUP * *************************************************** END OF PROGRAM

	NOTE: It is recommended that you run DTODSIZ twice weekly (either interactively or from a scheduled job) during peak periods of system activity to get a more accurate estimate of the largest dump file size possible for your system. Verify that the configured dump file size is greater than the largest possible dump. If dump files are too small, increase their size. After estimates become fairly consistent, execute DTODSIZ less frequently (for example, monthly) to confirm correct dump file size. Run DTODSIZ frequently whenever your system undergoes any substantial change in activity (for example, a change in the number of regular users).

Determine the number of dump files required

Determine the number of dump files that you want to preallocate. Base your decision on the cost of additional disk drives versus the risk of losing important dump information. You can lose information if a dump occurs before you can examine existing dump information and there are no additional dump files to store subsequent dump information.

Determine the number of disk drives required

Determine the number of disk drives that you need, based on the disk space requirements of AutoRestart/iX and the capacity of the disk drives to be allocated for dump file storage.

	NOTE: Up to 100 megabytes of disk space on a nonsystem volume set are reserved for MPE/iX system use. Include this space in your calculations for number of disk drives required for AutoRestart/iX.