Installation guide

Saving Memory Dumps
HP-UX version 11.00.03 Administering Fault Tolerant Hardware 5-43
Table 5-10. Dump Configuration Decisions
Consideration Dump Level:
Full Dump, Selective
Dump, or No Dump
compressed save
vs. uncompressed
save:
Using a Device for Both
Paging and Dumping:
system
recovery
time—If you
want to get your
system back up
and running as
soon as
possible,
consider the
following:
Choose selective
dumps and list which
classes of memory
should be dumped, or
enable HP-UX to
determine which parts
of memory should be
dumped based on
what type of error that
occurred.
Because
compressing the data
takes longer, if
sufficient disk space
is available but
recovery time is
critical, do not
configure savecrash
to compress the data.
Keep the primary paging
device separate (default
configuration), which
reduces system boot-up
time.
crash
information
integrity—If you
want to ensure
that you capture
the part of
memory that
contains the
instruction or
piece of data
that caused
crash, consider
the following:
The only way to
guarantee that you
capture everything by
doing a full dump. Full
dumps use a large
amount of space (and
takes a long time).
Ensure that you
define sufficient dump
space in the kernel
configuration.
Compression has no
impact on information
integrity.
Use separate devices for
paging and dumping. If a
dump device is enabled for
paging, and paging occurs
on that device, the dump
might be invalid.
disk space
needs—if you
have limited
system disk
resources for
post-crash
dumps and/or
post-reboot
saves, consider
the following:
If system disk space
is a limited, choose
either selective dump
mode (the default
more) or if disk space
is really critical,
choose no dump
mode. By choosing
this option, you can
save disk space on
your dump devices,
and in the HP-UX file
system area.
If the disk space in
the system’s HP-UX
file system area
(/var/adm/crash)
is limited, configure
savecrash to
compress your data
as it makes the copy.
If you have sufficient space
in /swap but limited space
in /var, or if part of a
memory dump resides on
a dedicated dump device
and the other on a device
used for paging, use the
savecrash -p command
to copy the pages in /swap
to /var.
Small-memory systems
that use /swap as a dump
device might be unable to
copy the dump to /var
before paging activity
destroys the data.
Large-memory systems
are less likely to need
paging (swap) space
during start-up, and less
likely to destroy a dump
/swap before it can be
copied.