We have a redhat 6 servers and memory is around 64GB, we are planing to configure kdump and I am confused about disk size I should set. Redhat suggest it would be memory + 2% more (that means around ~66GB Disk space). I need your suggestion what would be the best size I should define for kdump.
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Answer
First, don’t enable kdump unless Redhat support tells you to. KDumps don’t really produce anything useful for most Linux ‘customers’.
Second, kdump could (potentially) dump the entire contents of RAM into the dump file. If you have 64GB of RAM ..AND.. it is full when the kdump is triggered, then yes, the space for your kdump file will need to be what RH suggested. That said, most problems can be identified with partial kdumps. RH support has even said before to perform ‘head -c ‘ on the file before sending it in to reduce its size. Usually trimming it down to the first 64MBs.
Finally, remember to disable kdumps after you have finished trouble-shooting the issue. This isn’t something you want running constantly on any system above a ‘Development/Test’ level. Most importantly is to remember to clean this space out after a kdump has occurred.