Preparing to run the mkcd command

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To run the mkcd command, you 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 or DVD file system contents
  • Storing the CD or DVD images before they are recorded
The mkcd command creates the following file systems if they are not already present or if alternative file systems or directories have not been specified:
/mkcd/mksysb_image
Space requirement depends on the size of the mksysb image that is to be created. The mkcd command attempts to calculate this space and verify that adequate space is available before starting to create the mksysb image.
Note: When the mkcd command calculates the space requirements needed for the /mkcd/mksysb_image directory, it also adds the space used by the excluded files (/etc/exclude.rootvg). It is therefore possible that the mkcd command might not be able to create the /mkcd/mksysb_image directory.
/mkcd/cd_fs
Requires 645 megabytes (up to 4.38 GB for DVD)
/mkcd/cd_images
Requires at least 645 megabytes (up to 4.38 GB for DVD) of space. If the -R or -S flags are used to specify not removing the images and there are multiple volumes required, more space must be provided.

The space used in these file systems is only temporary (unless the -R or -S flag is specified to save the images). If the mkcd command creates the file systems, it also removes them. Each file system or directory might require over 645 megabytes (up to 4.38 GB for DVD).

If your machine does not have sufficient space, you can use NFS to mount some space from another server system; however, the file systems must be writable. You can create a /mkcd file system that is very large (1.5 GB for CD or 9 GB for DVDs). The /mkcd file system can then be mounted onto the clients when they want to create a backup CD or DVD for their systems. When creating very large backups (larger than 2 GB) with the mkcd command, the file system must be large-file enabled and the ulimit values must be set to unlimited.

The mkcd command with the -L flag allows the creation of DVD-sized ISO9660 images. The mkcd command with the -U flag allows the creation of UDF DVD images. You can also use the mkdvd command to create DVD-sized ISO9660 images.