How to determine the time required for dumping a vmcore file with kdump?

Environment

• Red Hat Enterprise Linux (RHEL) 5, 6, 7, 8, 9
• Kdump

Issue

• How to determine the time for dumping a vmcore file with kdump?
• How much time would be needed to dump the whole content of memory on a specific system configuration?
• For how long time should wait for kdump to dump the vmcore file.
• How long does it take to generate a vmcore?

Resolution

Dumping time depends on the options that are used for its configuration. Below are some of the factors which should be taken into consideration:

• Storage speed
• Memory speed
• Data Compression used
• Dump filter level
• Network if dump target is a remote storage

Estimation can be made by dumping whole memory to disk and measuring the time needed for it can be considered as probable value to dump the vmcore. However it would be generic value, no specific table will give time statistics.

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