Using the Dump Tools on Red Hat Enterprise Linux
8.5
To obtain kernel dumps of Linux on Z instances, you can
use the tools described, for example, kdump or VMDUMP. You can use DASD, tape, or SCSI dump
devices.
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Planning for dumps
Be prepared before disaster strikes! Consider what dump method you want to use, what size dumps you need to handle, and what possibilities exist to limit the size or spread the dump over several devices.
Using kdump
You can use kdump to create system dumps for instances of Red Hat Enterprise Linux .
Using a DASD dump device
To use a DASD dump device, you need to install the stand-alone DASD dump tool and perform the dump process. Then, copy the dump to a file in a Linux file system.
Using DASD devices for multi-volume dump
You can handle large dumps, up to the combined size of 32 DASD partitions, by creating dumps across multiple volumes.
Using a tape dump device
You can use a channel-attached tape as a dump device. To use a tape, you need to install the stand-alone tape dump tool and perform the dump process. Then, copy the dump to a file in a Linux file system.
Using a SCSI disk dump device
To use a SCSI disk, you need to install the stand-alone SCSI dump tool, perform the dump process, and copy the dump from a partition to a file in a Linux file system.
Creating dumps on z/VM with VMDUMP
Use VMDUMP to create dumps on z/VM® systems, using the z/VM reader as the dump medium.
Using virsh dump to create dumps on KVM hosts
The virsh dump command writes KVM guest dumps to a file in the KVM host file system.
Processing dumps
You can copy and transfer the dump file to another system, reduce the dump size, and send the reduced dump to IBM® Support.
Obtaining a dump with limited size
The mem
kernel parameter can make Linux use less memory than is available to it. A dump of such a Linux system does not need to include the unused memory. You can use the zipl size option to limit the amount of memory that is dumped.
Command summary
The descriptions of the commands contain only the relevant options and parameters, for a full description refer to the man pages.