Build a rescue image on an NWSSTG

 

One rescue solution for a logical partition is to create a small network storage space (NWSSTG) that can be left on the IFS solely for the purpose of rescuing logical partitions.

First, a quick explanation of what a Linux Rescue server normally entails. Many distributors include a rescue image on their installation disks that will start into a minimal version of their distribution that contains all the basic diagnostic tools, drivers and other utilities that would be useful for checking a previously existing logical partition. You can simplify this process by creating a network storage space with a rescue server in it at the time you install your logical partition.

Before creating a rescue image on network storage it is important to document the configuration information for each of your logical partitions. You will want to document the drive configuration which can be obtained from the /etc/fstab file. You will also want to capture the networking information that is reported when you run the command "ifconfig". It would also be good to create a list of the modules that are needed by each partition. You can see which modules are in use by using the "lsmod" command from within Linux. IBM recommends that you take the information obtained from the commands and files listed above and put them into files that can be stored on your rescue network storage space.

To create the rescue storage space, first consult your Linux documentation to see what amount of space is required for a minimum installation. Create a network storage space (CRTNWSSTG) that is slightly larger than the value listed in the distributor's documentation. For example if the documentation says a minimum server installation is 291 megabytes then you would want to create a storage space of 425 megabytes. Making the storage space larger allows space to create a swap partition, a PrEP start partition and allows room for you to install any extra software that you would like to have available in your rescue image. You may want to make a note in the storage space's description field telling what distribution was used to make the rescue image and warn that it should be saved. Next, link this storage space to a Network Storage Descriptor (NWSD). You don't need to create a new NWSD for this step. You could unlink an existing storage space and temporarily link your rescue storage space to any of your existing NWSD's.

Next, start your distributor's installation server as described in the documentation and follow the prompts. Make sure that you create a PrEP start partition if you choose to manually partition your install. When you get to the distributors package group selection display you are going to want to select the minimum number of packages supported. The name for the package group varies by distribution. Finally, let the installer complete its package installation and configuration.

After installation has finished, the installer will start up the server for you. At this time you should take some time to verify that the rescue server has all the utilities that you are going to need. For a logical partition, you are going to want to do an "rpm -qa | grep ibmsis" to make sure that the utilities to work with native disk are available. You should also make sure that the device drivers (i.e., pcnet32 for Ethernet and Olympic for token ring) that your partitions may require are installed. The kernel modules that have been compiled can be found in the /lib/modules/kernel version/kernel/drivers directory structure. You should also install any other special drivers or software packages that your logical partitions may require and ftp the files with the configuration information for your other logical partitions onto the rescue server network storage space at this time.

On some Linux Distributions, you will have to manually install the kernel after installation. Consult the appropriate installation documentation for details regarding installing the kernel.

Since you will be starting the rescue network storage space from network storage you need to make note of the path to the root partition on the rescue storage space. You can determine the root partition by doing the command 'cat /etc/fstab'. The partition that has "/" in the second column is your root partition. The distributor's documentation should also provide assistance in determining the root partition.

You are now done creating your rescue image. Shutdown your logical partition using "shutdown -h now" and vary the partition off after the shutdown has completed. After the partition has varied off unlink the rescue storage space and relink the NWSD's normal storage space.

 

Parent topic:

Back up and recover a logical partition