As we had always troubles to get reasonable fast dumps I took another attempt to figure out what's going on here.
I did a "time dd if=/proc/vmcore of=/dev/null" to find out a maximum read performance with about 20MB/s.
- The kdump operation time of RHEL6 is much longer than RHEL5's one, because reading /proc/vmcore is slower on RHEL6.
- kdump(2nd kernel) in RHEL6.0 is much slower than that in RHEL5.5.
I/O performance in which vmcore is collected by "core_collector cp":
RHEL5.5: About 121.9MB/s RHEL6.0: About 12.2MB/s
I/O performance in which vmcore is collected by "core_collector makedumpfile":
RHEL5.5: About 118.7MB/s RHEL6.0: About 19.2MB/
This is performance REGRESSION from RHEL5.5.
- Red Hat Enterprise Linux (RHEL) 6.0
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