The Virtualization Cookbook for SLES 10 SP2 - z/VM - IBM

2.2.2 Backup file naming convention
It is recommend that you keep copies of important z/VM and Linux configuration files. You
should always keep copies of original configuration files in case you need to go back to them.
Since z/VM file names are limited to 16 characters (eight for the file name and eight for the file
type), only the last four characters of the file type are used. This often requires some
characters to be overwritten. For the original file, the suffix ORIG is used, and for the most
recent working copy, the suffix WRKS (for “it WoRKS”!) is used. For example, the original USER
DIRECT file is copied to the file USER DIREORIG before it is modified the first time.
2.2.3 The command retrieve convention
2.3 Disk planning
The ability to retrieve past commands is a common tool. Often it is nice to retrieve in both
directions in case you “pass” the command you’re looking for. The default Linux shell, bash,
does this by default with the up arrow and down arrow keys.
There is a convention in z/VM to use the F12 function key (labeled PF12 on physical 3270
devices) to retrieve the last command, though it is not defined to all user IDs. There is no
convention retrieve commands in the other direction but it is possible to set another key to
that function. Therefore, F11 is used to retrieve forward since it is right next to F12. Also, the
same function is useful in the editor, XEDIT. The ? subcommand retrieves past commands, so
it is recommended that you assign it to F12.
There are different aspects to consider when planning how to choose and allocate disk
storage. Some aspects include the following
► Conventional ECKD DASD vs. FBA disks over SCSI/FCP
► 3390-3s vs. 3390-9s or large disk support
► Amount of disk storage per Linux image and how to allocate file systems
DASD vs. SCSI/FCP
This book describes how to use conventional ECKD DASD and does not discuss FBA disks
accessed over SCSI/FCP. This is not because either technology is superior, but simply
because DASD seems to be much more common than SCSI/FCP disks. If you were to use
SCSI/FCP disks, cloning with the clone.sh script would have to be modified to account for
World Wide Port Names and Numbers. Sometimes a combination of these two types of disk
storage is used - when that is the case the ECKD emulated DASD is often used for the root
file system and SCSI/FCP disks are used for large data storage areas.
3390-3s vs. 3390-9s
Emulated 3390-3s format to about 2.3GB, while 3390-9s are three times the size or about
6.8GB. Either size will work, though 3390-3s have been recommended over 3390-9s by some
performance analysts. This book describes mainly using 3390-3s, however, comments are
added where using 3390-9s differs - especially with installing z/VM.
Disk storage per Linux image
Disk storage has the following characteristics
10 The Virtualization Cookbook for RHEL 6