Description: Before z/OS V1R13, for each new release,
certain post-installation activities had to be done for the z/OS UNIX
System Services cron, mail,
and uucp utilities in order for the root
file system to be mounted read-only. Starting in z/OS V1R13, the /usr/lib/cron, /usr/mail,
and /usr/spool directories are provided as symbolic
links. Note that this migration action does not affect other mail
utilities such as tsmail, mailx,
and Communications Server sendmail.
| Element or feature: |
z/OS UNIX. |
| When change was introduced: |
z/OS V1R13. |
| Applies to migration from: |
z/OS V1R12. |
| Timing: |
Before the first IPL of z/OS V2R1. |
| Is the migration action required? |
Yes, if either of the following is true: - You have performed the post-installation activities to make uucp, cron,
or mail supported for a read-only z/OS
root. You do not necessarily have to be running with the z/OS root
as read only but only have the post-installation customization as
described in z/OS UNIX System Services Planning.
- You have used uucp, cron,
or mail facilities and have not performed
the post-installation customization as described in z/OS UNIX System Services Planning
|
| Target system hardware requirements: |
None. |
| Target system software requirements: |
None. |
| Other system (coexistence or fallback) requirements: |
None. |
| Restrictions: |
None. |
| System impacts: |
- Because the new symbolic links are directed to a
system-specific file system, other file systems are not affected by
this change. When shared in read-only mode, the z/OS root will
contain the /var symbolic links.
- If you use any of the utilities (uucp, cron,
or mail ), then review any files that these
utilities produce, such as logs. Now that the symbolic links, by default,
point to the /var location, ensure that you have
room for these utility-produced files in /var. This
might mean: (1) creating a separate file system for files (such as /var/spool,
as recommended in z/OS UNIX System Services Planning),
(2) moving existing separate file systems you already have to be mounted
under /var (from/etc, for instance),
or (3) enlarging your /var file system if you don't
have separately mounted file systems for these utilities.
|
| Related IBM Health Checker for z/OS check: |
Use check ZOSMIGV1R13_RO_SYMLINKS, available
with APAR OA35605 and APAR OA35636. |
Steps to take: Follow these steps:
Note: While this
migration action should be performed before the first IPL of z/OS
V2R1, the changes to use /var for this support can
be done at any time. Although previous documentation had shown the
use of /etc n examples, after further consideration,
we now recommend using /var for these utilities.
- If you currently use /etc or another directory
for post-installation customization for these utilities, decide
if you want to continue to use those directories or move to the /var
structure that is provided with z/OS V2R1. Moving to the /var structure
is recommended because:
- You can minimize any subsequent post-installation customization,
since the symbolic links to /var will be provided
for you by IBM. Continued use of non-/var directories may mean post-installation
work every time to remove the delivered structure and replace it with
your own.
- Continued use of /etc (or another directory),
requires you to manage and maintain the symbolic links required from /var to
that directory, which is “double symlinking.” This “double
symlinking” might be confusing for those that maintain the system.
- If you use /var for your post-installation
customization, then ensure that the /var file system
to be mounted at the z/OS V2R1 level of /var (or
subdirectories shown below) contains the following directories or
files for the utilities you are using. These will now be referenced
by symbolic links in the z/OS V2R1 root file system when
cron, mail, and uucp are used:
- /var/mail
- /var/spool
- /var/spool/cron
- /var/spool/locks
- /var/spool/cron/atjobs
- /var/spool/cron/crontabs
- /var/spool/uucp
- /var/spool/uucppublic
- /var/spool/uucp/.Xqtdir
- /var/spool/uucp/.Sequence
- /var/spool/uucp/.Status
- /var/cron
- /var/uucp/Systems
- /var/uucp/Devices
- /var/uucp/Dialers
- /var/uucp/Dialcodes
- /var/uucp/Permissions
- /var/uucp/config
Note that the /var file
system provided by ServerPac will contain these directories but not
the files, because the files are provided when the utilities are configured
and used. If you use to use the ServerPac /var and
add your files to that /var file system, that is
acceptable, as documented in Migrate /etc and /var system control files.
This action is similar to how you would merge an /var file
system provided by Server Pac with an existing file system.
If
you have any user files under /usr/spool, /usr/lib/cron,
or /usr/mail in the root file system (that is, they
have not been symlinked under /var or another directory
to support the read-only root), then those files must be moved to /var/spool, /var/cron,
or /var/mail (or another directory besides the /var that
you choose).
Reference information: See the following information:z/OS UNIX System Services Planning.