How to retrieve a vmcore from a raw partition?
Environment
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 5
- Red Hat Enterprise Linux 4
- Red Hat Enterprise Linux 3
- kdump
- diskdump
- netdump
Issue
- How to retrieve a vmcore from a raw partition?
Resolution
- The
dd
command can be used to retrieve a vmcore from a raw device. In the output below "X" indicates the block size of the backing storage.
[root@<hostname> ~]# dd if=/dev/<partition> of=/tmp/vmcore bs=X count=<size of ram>/X
- To determin the block size of the backing storage in bytes, the
blockdev
utility can be used as shown below:
[root@<hostname> ~]# blockdev --getbsz /dev/<device>
4096
- Alternatively, for kdump users on RHEL5 or above, it is possible to retrieve a vmcore saved on a raw partition with command below:
[root@<hostname> ~]# makedumpfile -R /path/to/vmcore/ < /dev/raw_partition
Diagnostic Steps
-
For further details regarding configuring kdump to get a vmcore, Please see the following
How to troubleshoot kernel crashes, hangs, or reboots with kdump on Red Hat Enterprise Linux -
For configuration of diskdump or netdump prior to RHEL5, Please see either of the following:
How do I use the diskdump utility to capture a vmcore in Red Hat Enterprise Linux 3 and 4?
How do I configure netdump on Red Hat Enterprise Linux 3 and 4?
This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.
Comments