Installation guide

partitions are full. It then writes the remaining crash dump
information to end of the primary swap partition, possibly filling that
partition.
_______________________ Note _______________________
If the aggregate size of all the swap partitions is too small to
contain the crash dump, the system creates no crash dump.
Each crash dump contains a header, which the system always writes to the
end of the primary swap partition. The header contains information about
the size of the dump and where the dump is stored. This information
allows
savecore to find and save the dump at system reboot time.
The way that a crash dump is taken can be controlled by the
dump_sp_threshold kernel attribute, which controls the partitions to
which the crash dump is written. The default value of 4096 causes the
primary swap partition to be used exclusively for crash dumps that are
small enough to fit the partition. In most cases, compressed dumps will fit
on the primary swap partition and you will not find it necessary to modify
this. If required, you can configure the system so that it fills the secondary
swap partitions with dump information before writing any information
(except the dump header) to the primary swap partition.
The value in the dump_sp_threshold attribute indicates the amount of
space you normally want available for swapping as the system reboots. By
default, this attribute is set to 4096 blocks, meaning that the system
attempts to leave 2 MB of disk space open in the primary swap partition
after the dump is written. Refer to the Kernel Debugging guide for
additional information on this setting.
To allow space for crash dumps, adjust the size of the swap partitions to
create temporary or permanent swap space. For information about
modifying the size of swap partitions, see the swapon
(8) reference page.
_______________________ Note _______________________
Be sure all permanent swap partitions are listed in the
/etc/fstab file. The savecore command, which copies the
crash dump from swap partitions to a file, uses the information
in the /etc/fstab file to find the swap partitions. If you omit a
swap partition, the savecore command might be unable to find
the omitted partition.
13–20 Administering Events and Errors