Determine whether to accept the new default values for certain zFS variables in the zFS IOEFSPRM configuration file

Description: Before z/OS V2R1, certain default values were used for the IOEFSPRM files or IOEPRMxx parmlib member variables meta_cache_size, metaback_cache_size, user_cache_size, or convert_auditfid. Starting in z/OS V2R1, new default values are created for them.

In z/OS V2R1, the zFS IOEFSPRM configuration file variable convert_auditfid default value was changed to ON so that all files and directories in zFS file systems can be uniquely identified in SMF audit records. The zFS IOEFSPRM configuration file variable user_cache_size default value will be changed to a value that is calculated based on the amount of real storage in the system. The zFS IOEFSPRM configuration file variables meta_cache_size and metaback_cache_size default values will be changed when both values are not specified to also be calculated based on the amount of real storage in the system. These are so that a system that has the capacity for more storage use and has sufficient space in the ZFS address space can have better performing caches.

Element or feature:

z/OS Distributed File Service

When change was introduced:

z/OS V2R1.

Applies to migration from:

z/OS V1R13 and z/OS V1R12.

Timing:

Before installing z/OS V2R1.

Is the migration action required?

Yes, if you do not want the new default values to take effect or if you want to change existing values to the new default values.

Target system hardware requirements:

None.

Target system software requirements:

None.

Other system (coexistence or fallback) requirements:

None.

Restrictions:

None.

System impacts:

If enough real storage exists, zFS can use more storage by default than it would have used in prior releases.

Related IBM Health Checker for z/OS check:

Use check ZOSMIGV2R1_ZFS_VERITY_CACHESIZE introduced in APAR OA42672. This check determines if you are using the default meta_cache_size, metaback_cache_size and user_cache_size and further indicates whether the new defaults would affect you. See IBM Health Checker for z/OS User's Guide.

Steps to take: Follow these steps:

Look for these:
- IOEFSPRM files or IOEPRMxx parmlib members that do not specify both meta_cache_size and metaback_cache_size options.
- IOEFSPRM files or IOEPRMxx parmlib members that do not specify the user_cache_size option.
- IOEFSPRM files or IOEPRMxx parmlib members that do not specify convert_auditfid settings.
- Programs that use zfsadm format commands where unique auditfids are not desired.
- JCL that contains calls to ioeagfmt that create aggregates for which unique auditfids are not desired.
- Programs that use zFS format API where unique auditfids are not desired.
Take these actions:
- For meta_cache_size, metaback_cache_size, or user_cache_size, if the old default values are desired, specify these values in your IOEFSPRM files or IOEPRMxx parmlib members.
- For auditfid, if you want the previous defaults, specify -nonewauditfid on calls to ioeagfmt or zfsadm format and convert_auditfid=OFF in your IOEFSPRM files or IOEPRMxx parmlib members.

Reference information: None.