Introduction to Backups on CD

Creating a backup CD is new function that has been added to AIX Version 4.3.3. It is similar to making a backup tape for your personal use, but with some noticeable differences.

You must obtain the hardware and software necessary to create a CD. IBM does not sell or support the software or hardware that is used to create CD's. The new command for this process, mkcd, requires that you already have the software to create a CD-ROM file system (Rock Ridge) and to "burn" or write the CD. Some of the hardware and software that was tested with this procedure includes:

For more information about CD-R drives and CD-R creation software, refer to the following file:

/usr/lpp/bos.sysmgt/README.oem_cdwriters

Once you decide what hardware and software you want to use and obtain it, you will need to create the appropriate links to scripts that have been written that will work with the mkcd command. For example, if you are using Jodian software, then you will need to create the following links:

ln -s /usr/samples/oem_cdwriters/mkrr_fs_jodian /usr/sbin/mkrr_fs
ln -s /usr/samples/oem_cdwriters/burn_cd_jodian /usr/sbin/burn_cd

In order to run the mkcd mkcd command, you will need extra working space. A separate file system or directory is required for each of the following:

• storing a mksysb or savevg image
• storing the CD file system contents
• storing the CD images before they are recorded

The mkcd command will create the following file systems if they are not already present, or if alternate file systems or directories have not been given:

/mkcd/mksysb_images
/mkcd/cd_fs
/mkcd/cd_images

The space used in these file systems will only be temporary (unless the -R or -S flag is specified to save the images). If the mkcd command creates the file systems, it will remove them. Each file system or directory could require over 640 megabytes. The /mkcd/cd_fs directory will need 640 megabytes. The /mkcd/mksysb_images directory's space requirement will depend on the size of the mksysb image that will be created. The mkcd process will attempt to calculate this space and verify that adequate space is available before starting the mksysb image. The /mkcd/cd_image directory will be need at least 640 megabytes of space. If the -R or -S flags are used to specify not removing the images, and there are multiple volumes required, then more space will have to be provided.

If you don't have space on your machine, you may want to NFS mount space from another server system, however, the file systems must be writeable. You could create a /mkcd file system that is very large (1.5 gig) and then create subdirectories cd_fs, mksysb_images and cd_images under /mkcd. Then /mkcd could be mounted on to the clients when they wanted to create a backup CD on their systems.

Personal and Generic backup CD's

There are two types of backup CD's that can be created. The first is what we call a "personal" backup CD. This type is similar to a backup tape, in that it will only boot and install the machine on which it was created.

The second type of CD is a "generic" backup CD. This type of backup can be used to boot any RS/6000 machine running the AIX operating system. It contains 3 boot images and all the device and kernel packages necessary to install any system. The mksysb image that is stored on the CD does not require that all the devices be installed in it, because the install process will install the needed devices for that machine from the packages on the CD. This type of backup CD might be used to install (clone) a large number of machines in a customer's environment. This is particularly convenient when each machine in the system environment needs to have the same image installed, but may not all have the same hardware configuration.

There are SMIT (smit mkcd) and Web-based System Manager Backups (wsm backup) interfaces available for the mkcd command. The Web-based System Manager Back Up to CD TaskGuide will help you through the required steps and will even create the links to the OEM scripts for you.

Another option available with the mkcd command is the ability to create a savevg CD. This CD has a copy of a non-rootvg volume group on it, and is useful for volume groups that contain user data. At this time, the mkcd command only supports saving one volume group to a CD at a time. However, if your rootvg image and savevg image were small enough to fit on one CD, then you could save them both by taking advantage of the -l (stacklist) flag. This flag gives a list of images to copy to the CD, and the -z (customization_script) flag. If you make a copy of a non-rootvg volume group ahead of time, and then write a script that calls restvg, then your non-rootvg, would be restored to hdisk2 at the end of the install of rootvg. For example:

restvg -d /SPOT/usr/sys/inst.images/savevg_image hdisk2

This procedure would only be recommended if you knew that you wanted to restore the non-rootvg volume group every time you installed. Otherwise, you might just want to store it on the CD, then use restvg (smit restvg or wsm lvm) to restore it after reboot. The restvg command will be able to restore from CD if the name of the image is savevg_image.