32.2. Configuring the kdump Service
There are three common means of configuring the
kdump service: at the first boot, using the Kernel Dump Configuration graphical utility, and doing so manually on the command line.
A limitation in the current implementation of the
Intel IOMMU driver can occasionally prevent the
kdump service from capturing the core dump image. To use
kdump on Intel architectures reliably, it is advised that the IOMMU support is disabled.
It is known that the
kdump service does not work reliably on certain combinations of HP Smart Array devices and system boards from the same vendor. Consequent to this, users are strongly advised to test the configuration before using it in production environment, and if necessary, configure
kdump to store the kernel crash dump to a remote machine over a network. For more information on how to test the
kdump configuration, see Section 32.2.4, “Testing the Configuration”.
32.2.1. Configuring kdump at First Boot
When the system boots for the first time, the firstboot application is launched to guide the user through the initial configuration of the freshly installed system. To configure
kdump, navigate to the Kdump section and follow the instructions below.
- Select the Enable kdump? check box to allow the
kdumpdaemon to start at boot time. This will enable the service for runlevels
5, and start it for the current session. Similarly, unselecting the check box will disable it for all runlevels and stop the service immediately.
- Click the up and down arrow buttons next to the Kdump Memory field to increase or decrease the value to configure the amount of memory that is reserved for the
kdumpkernel. Notice that the Usable System Memory field changes accordingly showing you the remaining memory that will be available to the system.
This section is available only if the system has enough memory. To learn about minimum memory requirements of the Red Hat Enterprise Linux 6 system, read the Required minimums section of the Red Hat Enterprise Linux Technology Capabilities and Limits comparison chart. When the
kdump crash recovery is enabled, the minimum memory requirements increase by the amount of memory reserved for it. This value is determined by the user, and defaults to 128 MB plus 64 MB for each TB of physical memory (that is, a total of 192 MB for a system with 1 TB of physical memory). The memory can be attempted up to the maximum of 896 MB if required. This is recommended especially in large environments, for example in systems with a large number of Logical Unit Numbers (LUNs).