Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Booting and Shutdown
Abnormal System Shutdowns
Chapter 5542
Dump Level You are reading this section because disk space is a limited
resource on your system. Obviously, the fewer pages that you have to dump, the
less space is required to hold them. Therefore, a full dump is not recommended. If
disk space is very limited, you can always choose no dump at all.
However, there is a happy medium, and it happens to be the default dump
behavior; it is called a selective dump. HP-UX can do a pretty good job of
determining which pages of memory are the most critical for a given type of
crash, and save only those. By choosing this option, you can save a lot of disk
space on your dump devices, and again later, in your HP-UX file system area. For
instructions on how to do this, see “Defining Dump Devices” on page 542.
Compressed Save versus Noncompressed Save Regardless of whether you
choose to do a full or selective save, whatever is saved on the dump devices needs
to be copied to your HP-UX file system area before you can use it.
NOTE Beginning with HP-UX Release 11.0, it is possible to analyze a crash dump
directly from dump devices using a debugger that supports this feature (see the
caution in the section called “Analyzing Crash Dumps” on page 554). But if you
need to save it to removable media, or send it to someone, you will first need to
copy the memory image to the HP-UX file system area.
If the disk space shortage on your system is in the HP-UX file system area (not in
the dump devices), you can choose to have savecrash (the boot time utility that
does the copy) compress your data as it makes the copy.
Partial Save (savecrash -p) If you have plenty of dump device space but are
limited on space in your HP-UX file system, you can use the -p option to the
savecrash command. This command copies only those pages on dump devices
that are endangered by paging activity (the pages residing on devices that are
being used for both paging and dumping). Pages that are on dedicated dump
devices are not copied.
To configure this option into the boot process, edit the file
/etc/rc.config.d/savecrash and uncomment the line that sets the
environment variable SAVE_PART=1.
Defining Dump Devices
This section describes procedures for defining the dump devices that
your system can use when a crash occurs.