If your system crashes, it writes its memory image to the dump device. The default dump device is the swap area, /dev/swap, but you can define an alternative dump device in one of two ways:
Boot:prompt, or by including this as part of the default bootstring in the boot defaults file, /etc/default/boot; see the bootstring(HW) and boot(F) manual pages for more information. You can specify a tape drive as the dump device. For example:
define the dump device to be a SCSI tape drive or a cartridge tape drive respectively. This can be useful if the size of the swap area is too small to hold the system image -- if, for example, you have configured a swap area smaller than the amount of physical memory on your system.
If you do not want the system to save its memory image, specify:
define the dump device to be a SCSI tape drive or a cartridge tape drive, respectively.
Note that you must edit sassign(F) and then relink the kernel to redefine the dump device.
If you also need to find out which files were open to processes at the time of the crash, you will also need to copy the contents of the filesystems.
The complementary command
copies a memory image from tape or floppy disk to a file:
To check the validity of a memory image, you can use the
memsize returns an error if the memory image is corrupted.