HP 3000 Manuals HP 3000 Manuals
DUMP and AutoRestart Enhancements by Jim Miller Commercial Systems Division There are several changes to DUMP to decrease dump time and decrease the size of dumps. Both dumping to tape (DUMP) and dumping to disk (the dump to disk feature of AutoRestart) have these changes. Change in DUMP Option The default has been improved, DUMP is no longer the same as DUMP SUBSET=ALL. The default now dumps less, for smaller and faster dumps (DUMP and DUMP SUBSET=DEFAULT). The DUMP SUBSET=ALL option is for those rare cases when you must get that data HP has recently selected to exclude from dumping. 32 Kb Tape Blocks DUMP now writes 32 Kb tape blocks instead of 16 Kb blocks when writing to tape devices that support the larger tape block size. On 1/2-inch tape drives this should increase the speed and may reduce the number of physical tapes required. DAT drives are unaffected by this change.
\ \ \ Important Details \ Please Read HP7978A and earlier tape drives will not be able to read dumps written with HP7980 and later drives. The general rule is that a tape device that has a 16 Kb per block upper limit will not be able to read a DUMP tape written by a tape device that supports 32 Kb blocks.
Other Changes Producing faster dumps is an important objective for MPE/iX and the DUMP project. Toward that end a number of internal changes have been made in order to increase dump's performance. Caching some disk data pages and re-aligning some I/O buffers are examples. The results of these changes will be a reduction in dump time of at least 1 minute per disk device dumped to 1/2 inch tape drives on mid- and high-end systems. Systems using DAT drives for dump should also experience some improvement. System Volume Set Dump Size Reduction The System Volume Set is the only volume set that dumpworthy data exists on that is needed for the analysis of most problems (99%+). Dump size is reduced by about one Megabyte of dump data information per User Volume Set disk device even if there is no other dumpworthy data on the disk drive--which there almost never is. In comparison to system Release B.40.00, most customers dump times will be reduced by between 1/2 minute to 2 minutes per disk device not dumped, saved primarily by not checking for dumpworthy data on the device. Customers with a large number of disk devices in User Volume Sets will see substantial improvements in dump time. There are two cases where the User Volume sets need to be dumped. * Rare classes of OS problems with User Volume sets; or * Customer runs a program with the dumpworthy option, and the program or user's XL is on a user volume. In the second case, it is advisable to put the program and user's XL on the system volume set while the program runs with the dumpworthy option. It is not necessary for the program files to be put into a different account or group, since files can selectively be put onto the system volume set. When needed, use of SUBSET=ALL option for DUMP will dump dumpworthy data from all mounted volumes. Main Memory Some object classes, which are already not dumped when on disk, will no longer be dumped from main memory. The amount of data and time saved by this change varies with the application set that the customer is using. DUMP data may be reduced by up to 80% of main memory under some situations. It is also possible that little reduction will occur. DUMP SUBSET=ALL will dump all of main memory in the unlikely event that this reduction results in the inability to resolve a particular problem.