Novell will probably request a core dump when a server experiences a lockup or abend and other troubleshooting has failed to resolve the problem. A core dump is a data file containing a copy of a NetWare server’s memory at the time the server abended. Core dumps can be analyzed by Novell engineers and are often the key to finding software bugs.
To prepare the environment for a core dump, download the nwcoredumpd utility to a location on the host server. You can get the utility from the Novell Support Web site. See TID 3281847.
NOTE:For this release, nwcoredumpd works for 32-bit Xen host only.
To write a core dump from a Xen virtual machine to the local Xen host or to a remote ImgHost, the nwcoredump utility must be running on the local Xen virtual machine host. You can start this utility any time before starting the core dump.
Log in to the Xen Host server (Dom0) as user root.
Start the nwcoredumpd utility by entering the following command at the command line prompt:
path /nwcoredumpd coredump_base_path
Coredump_base_path is the directory where you want the core dump saved or written.This directory must already exist before you start the core dump.
For example,
If the nwcordumpd utility is in the current directory and you want the core dumps written to the same location, enter
./nwcoredumpd .
If the nwcordumpd file is in a directory named /opt/novell/ and you want the core dumps written to the /coredumps directory that you created, then enter:
/opt/novell/nwcoredumpd /coredumps
Create the core dump as follows:
Start a core dump in one of these two ways:
Select the core dump option when an abend occurs.
NOTE:After the core dump is completed, the server abend handler restarts or reboots itself depending on the Auto Restart After Abend parameter setting.
Manually start a core dump by entering .c while in the NetWare internal debugger.
You can enter the debugger at any time by typing 386debug or by pressing these keys: Alt+left-Shift+right-Shift+Esc.
HINT:Press and hold the right-Shift and Alt keys with the right hand, then with the left hand press and hold the left-Shift and press the Esc key last.
Then enter .c at the # prompt and respond to the Section 7.5.3, Virtualized NetWare Core Dump Prompt Options.
When the core dump is finished, do one of the following if you manually started the core dump:
Enter g to resume the server’s execution if possible.
Enter h to display Help.
Enter q to exit the debugger.
If the server was hung when you entered the debugger, it probably will not resume the server’s operation.
If the server abended, it is best not to resume the server’s operations.
Whether you selected the core dump option after an ABEND or are forcing a core dump, you have the following options when responding to the core dump prompts.
Table 7-1 Virtualized NetWare Core Dump Prompt Options
|
Prompt |
Option |
|---|---|
|
Reboot server after coredump? |
Y : Reboots server after the core dump N : Leaves the server in the same state after core dump |
|
Lists available local drives and available free space on each |
Informs you of local partitions available for the core dump. |
|
Coredump Type |
Full includes all the server memory in the core dump. For some cases, this is the recommended option. Full w/o cache includes all server memory except file cache (disk cache). Generally, this is the recommended option. Novell technical support will advise you when to make a full core dump. |
|
Compress Coredump |
Yes is the recommended option No |
|
Where should diagnostic core dump be saved? |
XENHOST saves the file to local XEN host machine (DOM 0) The virtual machine does not need to be running to obtain the file. For details, see Saving a Dump to the Xen Host, DOM 0 (XENHOST Option). NETWORK saves the core dump file to the remote IMGHost at the IP address specified. For details, see Saving a Core Dump to a Remote IMGHost (NETWORK Option). HDISK saves the core dump file to a local FAT partition. The drives that are available were listed when the core dump was started. The partition (logical drive) must already exist on the virtual machine. After the core dump completes, you need to reboot the server before the core dump can be accessed or transferred. For details, see Saving a Core Dump to a Local FAT Partition. |
Log in to the virtual machine server as user root.
Make sure the nwcoredumpd utility is started. See Section 7.5.1, Starting the nwcoredumpd Utility.
The Xen host agent receives the core dump from the virtualized NetWare server and stores it in a subdirectory based on the virtual server’s name and a unique file name with an .img extension.
For example, if you sent several core dumps from a server named DASERVER1 and you specified /coredumps as the base_coredump_path, you would find a core dump files similar to the following in this directory.
/coredumps/daserver1
070917_001.img
070918_002.img
070921_003.img
Log in to the virtual machine server as user root.
Make sure the nwcoredumpd utility is started. See Section 7.5.1, Starting the nwcoredumpd Utility.
The nwcoredumpd utility in this case automatically routes the core dump on to the remote IMGHost.
Make sure a remote image host agent, by doing the following:
On a NetWare server, load imghost.nlm
When loading the imghost.nlm or running the imghost.exe, you can specify a directory where you want the received core dumps to be saved (the directory must already be created) or accept the default paths.
For example: load imghost sys:coredump
The default path for imghost.nlm is volume sys:.
The default path for imghost.exe is the current working directory.
At the “Where should the diagnostics coredump be sent?” prompt, select the option.
At the “IP Address of IMGHOST” prompt, enter the IP address of the server or workstation where you started the image host agent.
The image host agent receives the core dump from server and stores it in a directory based on the server name and assigns a unique filename based on the date (year, month, day, version) of the core dump with an .img extension.
For example, if a file was sent from a server named DASERVER1 on September 17, 2007 to a server running imghost.nlm, the DASERVER1\070917aa.img directory and file would be created on volume sys:.
After you start the core dump, you are asked to specify the drive letter and file path that the file will be written to.
The drive can be any writable local device that contains enough storage space. This could be the C: drive or another FAT partition. The partition (logical drive) must already exist on the virtual machine. After the core dump completes, you need to reboot the server before the core dump can be accessed or transferred.
You can also create a logical core dump drive by using Novell Remote Manager and save the core dumps to this drive just as you would to the local C: drive or other local FAT partitions. For more information, see Creating a Logical Volume for Saving Core Dumps
in the NW 6.5 SP8: Novell Remote Manager Administration Guide.
When the image is written to a local hard drive on the server, the default name of the image file is c\:coredump.img.
To write to a different device, substitute the drive letter and filename. For example, d:\cdump2.img
After the core dump is finished:
Reboot the server.
The core dump cannot be accessed or transferred until this step occurs.
The server does not need to be rebooted if the core dump was saved to a removable, USB drive or device.
The image file can be sent to Novell (if you have opened a support incident).
The image file can also be written to a network drive later. You can do this by using Novell Remote Manager (recommended), by using the TBX commands, or by using any other third-party NLM that provides this functionality.
IMPORTANT:You will be expected to patch the server to the latest Support Pack before Novell requests a core dump. To send a core dump file to Novell, you must first open a support incident, which will be billable. You are not charged until the incident is resolved or closed. If the problem is a Novell bug and no patches were previously available, then there is no charge.
Before sending the core dump to Novell, contact a support representative to open a support incident. You will be assigned to a Support Engineer who will help you analyze the core dump file. The Support Engineer will make arrangements to receive the core dump.