HP 3000 Manuals HP 3000 Manuals
Determining Your Dump-to-Disk Needs
Give careful consideration to managing your system's dump files. You can
preallocate from one to ten dump files. Due to the large size of each
dump file, the actual number of dump files that you can preallocate
depends on the disk space or disk drives available to AutoRestart/iX.
Logically configure and physically install one or more disk drives before
you configure AutoRestart/iX. To determine your disk drive needs prior to
AutoRestart/iX configuration, follow these steps:
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:
* number of active jobs and sessions
* number of child processes associated with the jobs and sessions
* memory size
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:
* Estimate using the number of active jobs/sessions.
* Estimate using the DTODSIZ utility (only if you have already
installed AutoRestart/iX on your system).
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
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| | | | |
| # Active | Main Memory | Dump Size | Dump Size |
| Jobs/Sessions | Size | Low Estimate | High Estimate |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| 50 | 64 MB | 94 MB | 154 MB |
| | 96 MB | 106 MB | 166 MB |
| | 128 MB | 119 MB | 179 MB |
| | | | |
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| | | | |
| 100 | 64 MB | 124 MB | 244 MB |
| | 96 MB | 136 MB | 256 MB |
| | 128 MB | 149 MB | 269 MB |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| 150 | 64 MB | 154 MB | 334 MB |
| | 96 MB | 166 MB | 346 MB |
| | 128 MB | 179 MB | 359 MB |
| | | | |
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| | | | |
| 200 | 64 MB | 184 MB | 424 MB |
| | 96 MB | 196 MB | 436 MB |
| | 128 MB | 209 MB | 449 MB |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| 250 | 64 MB | 214 MB | 514 MB |
| | 96 MB | 226 MB | 526 MB |
| | 128 MB | 239 MB | 539 MB |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| 300 | 64 MB | 244 MB | 604 MB |
| | 96 MB | 256 MB | 616 MB |
| | 128 MB | 269 MB | 629 MB |
| | | | |
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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.
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