Dump tools

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When the system hangs, create a memory dump.
The following dump tools are available:
  • The DASD dump tool writes the memory dump directly to a DASD partition. It supports both ECKD™ and FBA DASDs.
  • The tape dump tool writes the memory dump directly to an ESCON/FICON tape device.
  • The SCSI dump tool writes the memory dump into file system. It is supported for LPAR and z/VM® .
  • The kdump feature is a two stage dump tool. This feature is made available through a Linux kernel and initial RAM disk that are preloaded in memory, along with a production system.
  • VMDUMP (for z/VM guest operating systems) writes the memory dump to z/VM spool space (VM reader). VMDUMP uses a dump format specific to z/VM, the dump must be converted. Do not use VMDUMP to dump large VM guests; the dump process is very slow.

As of LinuxONE III, you can use NVMe devices as stand-alone dump devices for Linux® in LPAR mode or in a DPM partition.

In particular, the Using the Dump Tools book contains a chapter about handling large dumps that describes how to split large dumps, for example, with makedumpfile.