Normal scenario, Every Linux experts are facing number of server hung cases/issues, we have to know what is the RCA for this. So, need to enable/configure kdump on the server. Let me explain how can we configure kdump in the server.
Kdump captures the real time memory information as a dump file known as vmcore (Virtual Memory Core). A vmcore is a dump of all memory contents on a system at a point in time. kexec is a fastboot mechanism which helps kdump service to generate vmcore.
I would recommend to enable kdump service and test it as mentioned in the below article :
How to troubleshoot kernel crashes, hangs, or reboots with kdump on Red Hat Enterprise Linux
https://access.redhat.com/solutions/6038#testing
Note that, when you test kdump, the server will reboot automatically and collect a vmcore at the target location
==> We would require a vmcore file at the time of server hung to troubleshoot further on the server hang issue.
Hence once you configured the kdump as mentioned above, and if the issue happens again, please trigger the sysrq manually and collect the vmcore file. Once you share the vmcore file at the time of issue, we can help you with further investigation. Below articles will help you for the same.
How can sysrq signals be triggered through a DELL DRAC in order to troubleshoot a hung system
https://access.redhat.com/solutions/453673
How to use the SysRq facility to collect information from a RHEL server
https://access.redhat.com/solutions/2023
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kexec
kexec is a fastboot mechanism that allows booting a Linux kernel from the context of an already running kernel without going through the BIOS. Since BIOS checks at startup can be very time consuming (especially on big servers with numerous peripherals), kexec can save a lot of time for developers who need to reboot a machine often for testing purposes
kdump is a reliable kernel crash-dumping mechanism that utilizes the kexec software. The crash dumps are captured from the context of a freshly booted kernel; not from the context of the crashed kernel. Kdump uses kexec to boot into a second kernel whenever the system crashes. This second kernel, often called a capture kernel, boots with very little memory and captures the dump image.
The first kernel reserves a section of memory that the second kernel uses to boot. Be aware that the memory reserved for the kdump kernel at boot time cannot be used by the standard kernel, which changes the actual minimum memory requirements of Red Hat Enterprise Linux. To compute the actual minimum memory requirements for a system,
lxserver 