Red Hat Enterprise Linux 5 Administration Unleashed

438CHAPTER 21Monitoring and Tuning the Kernel. Remote SSH filesystem: The SSH server must accept connections from the system, andSSH keys must be set up for the SSH user provided. After configuring SSH keys forthe user as discussed in Chapter 17, “Securing Remote Logins with OpenSSH,”execute the service kdump propagate command as the root user to enter the SSHpassphrase and allow the specified user to transfer files to the SSH server withoutbeing prompted for a password or passphrase.Because this user now has SSH access to the SSH server without having to enter apassword, it is recommended that you use a dedicated SSH user for Kdump. The usershould only have access to write to the designated directory for saving dump files.The scp utility is used for the transfer.Each dump file is written to /var/crash/-/ in the specified shareddirectory on the SSH server. The hostname of the crash system and the date are usedin the directory path so that the server can store multiple dump files, assumingenough disk space is available. Replace the username and the server name such askdump@fileserver.example.com:net For all of these location options except the raw partition, the path option in kdump.confdetermines the directory path appended to the end of the desired location. If a path isnot set, the core file is saved in the /var/crash/ directory inside the set location. Tochange this directory, add the following line to /etc/kdump.conf:path Additional Kdump OptionsTwo more options exist in the /etc/kdump.conf file:. Compression and filtering: Use the makedumpfile program included with the kexectoolspackage to compress or filter the core dump file. Compression can greatlydecrease the size of the dump file, which is useful for systems with limited diskspace or network transfers. Cannot be used if the save location is a raw partition ora remote SSH filesystem. After specifying a location in /etc/kdump.conf, add thefollowing line (execute the makedumpfile -h command to view a list of options) :core_collector makedumpfile . Default action: If Kdump is configured to save to the local filesystem, the systemreboots after saving the file, regardless of whether the save was successful or not. Forany of the other save locations fails, Kdump tries to save to the local filesystem andthen reboots. If you want to Kdump to skip trying to save to the local filesystemafter it fails to write to a different location, add the following line to the end of/etc/kdump.conf:default Replace with reboot to reboot the system after failing or shell so that youcan try to save the dump file manually.