Why is kdump generating incomplete vmcore?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux( All version)

Issue

  • In what scenarios can kdump generate incomplete vmcore?

Resolution

  • Incomplete vmcores are generated when dumping operation is interrupted. The common causes of incomplete dumps are:

    • Exhaustion of free space on kdump target. Even if page exclusion and core compression are enabled, the only sure way to guarantee a successful vmcore is to have free space on disk at least equal to physical RAM.
    • Cluster or hardware mechanisms rebooting the server while dumping is in progress. If cluster or hardware based watchdog timer mechanisms are present, make sure that the delay before reboot will be triggered is adequate to complete the dumping process.
    • Local or remote kdump target becomes inaccessible.
    • kdump kernel crashes while dumping is in progress.
    • kdump kernel runs out of memory.

  • when incomplete vmcores are generated, the console logs collected while triggering a kernel panic frequently help in finding why incomplete vmcores are generated.

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