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 his 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.