kdump-utils/kdumpctl.8 at main · rhkdump/kdump-utils · GitHub

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.TH KDUMPCTL 8 2015-07-13 kdump-utils

.SH NAME
kdumpctl \- control interface for kdump

.SH SYNOPSIS
.B kdumpctl
.I COMMAND

.SH DESCRIPTION
.B kdumpctl
is used to check or control the kdump service.
In most cases, you should use
.B systemctl
to start / stop / enable kdump service instead. However,
.B kdumpctl
provides more details for debugging and a helper to set up ssh key authentication.

.SH COMMANDS
.TP
.I start
Start the service.
.TP
.I stop
Stop the service.
.TP
.I status
Prints the current status of kdump service.
It returns a non-zero value if kdump is not operational.
.TP
.I restart
Is equal to
.I start; stop
.TP
.I reload
reload the crash kernel image and initramfs without triggering a rebuild.
.TP
.I rebuild
rebuild the crash kernel initramfs.
.TP
.I propagate
Helps to setup key authentication for ssh storage since it's
impossible to use password authentication during kdump.
.TP
.I showmem
Prints the size of reserved memory for the crash kernel in megabytes.
.TP
.I estimate
Estimate a suitable crashkernel value for the current machine. This is a
best-effort estimate. It will print a recommended crashkernel value
based on the current kdump setup, and list some details of memory usage.
.TP
.I get-default-crashkernel
Return the default crashkernel value provided by kdump-utils.
.TP
.I reset-crashkernel [--kernel=path_to_kernel]
Reset crashkernel to default value recommended by kdump-utils. If no kernel
is specified, will reset KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump
or the current running kernel's crashkernel value if KDUMP_KERNELVER is empty. You can
also specify --kernel=ALL and --kernel=DEFAULT which have the same meaning as
grubby's kernel-path=ALL and kernel-path=DEFAULT. ppc64le supports FADump and
supports an additional [--fadump=[on|off|nocma]] parameter to toggle FADump
on/off.

Note: The memory requirements for kdump varies heavily depending on the
used hardware and system configuration. Thus the recommended
crashkernel might not work for your specific setup. Please test if
kdump works after resetting the crashkernel value.
.TP
.I test [--force]
Test the kdump by actually trigger the system crash & dump, and check if a
vmcore can really be generated successfully based on current config and
environment. After system reboot back to normal, check the test result
by "kdumpctl status". Note, fadump is not supported.

If the optional parameter [--force] is provided, there will be no confirmation
before triggering the system crash. Dangerous though, this option is meant
for automation testing.
.TP
.I setup-crypttab
Add the 'link-volume-key' option to /etc/crypttab so vmcore can be saved to
LUKS-encrypted disk volume. For more info on link-volume-key option,
please "man crypttab".

This step is optional. If kdump.service can start successfully, there is no
need for this step. You can confirm if this step is needed by running
"kdumpctl restart". If you need to input any passpharse to unlock the the
encrypted volume, then please run "kdumpctl setup-crypttab".

Note this subcommand is only helpful to x86_64 for now.

.SH "SEE ALSO"
.BR kdump.conf (5),
.BR mkdumprd (8)