System information

Sharing and maintaining SLES 10 SP2 Linux under z/VM 61
Think of all the things in /usr/, /boot/, / etc. to begin with. All of this runs read-only, and any
read-write work is done in the home directory or /etc/ or /var/ etc... These software
packages work great, and no explanation is needed. Just install them on S10RWTST/MNT and
away you go.
2. Read-only, but picky and needs to be tricked...
Any software that can run almost entirely read-only, just the same as vi or bash, but due to a
couple things attempting to write somewhere like /opt/, it isn't a plug and play operation.
Innovation Data Processing’s fdrupstream is an example. It is installed back on S10RWTST/MNT
in /opt/fdrupstream/. However, when it boots it attempts to drop a .pid file, and one or two
other files as well as a log file. Luckily in the configuration, you can specify most of where you
want those to go. Choose /var/fdrupstream/. There was one last hanger on. It was
attempting to write to a file in /opt/fdrupstream still. So, on S10RWTST, I moved that file to
/var/fdrupstream/, and symlinked the file from /opt/fdrupstream/. Luckily that was the last
step, and now FDRupstream comes read-only with each new machine and all that needs to
happen is a small configuration change to a file in /var/fdrupstream/. Hence read-only, but
picky.
3. Read-write, mounted and attached
IBM Tivoli Monitor (ITM) works this way. We attach a 321 minidisk to any machine that needs
the agent, 500 cylinders. We then run a script which formats, then DDR's a “gold” install of
ITM over and installs all of the boot scripts and mounts ITM at /local/ITM/ (mainly since
/local/ is read-write and can be used easily for mount points).
4. Read-write and never going to run on a read-only machine
An example is IBM’s Omegamon for z/VM and Linux. This program attempts to install so
many places, /usr/bin/, /opt/IBM/, etc. and then later attempts to access so many files
read-write in those read-only areas, that running it read-only just isn't feasible. This is the
reason you still have 11Bx disks under S10GOLD.
1.8 Other considerations
This paper describes some miscellaneous topics such as:
򐂰 “Utilizing logical volumes” on page 61
򐂰 “Implementing /home/ with automount, NFS and LDAP” on page 62
򐂰 “Enabling Collaborative Memory Management (CMM)” on page 63
1.8.1 Utilizing logical volumes
Using Linux Logical Volume Manager (LVM) would make a lot of sense for file systems that
are likely to grow large such as /var/ and perhaps /srv/. They were not implemented in this
paper for simplicity and due to time constraints.
If you decide to implement your solution using logical volumes, and you plan to use the
mnt2rogld.sh script, it would have to be modified accordingly.
Following is a sample function to create logical volumes on the target system that was lightly
tested. It targets device 2B0 which is linked read-write at virtual address 22B0 and the device
file is set in the variable dev22b0:
function makeLVs
{