Quiesce processing for zFS file systems has been modified in z/OS V2R1. The zFS commands and zFS APIs used to quiesce and unquiesce zFS file systems are unchanged, but the way quiesce works internally and the way the quiesce status is displayed are modified.

In z/OS V2R1, the name "zSeries® File System" was changed to "z/OS File System". The document z/OS Distributed File Service zSeries File System Administration was retitled to z/OS Distributed File Service zFS Administration.

Beginning with z/OS V2R1, zFS provides an optional, new format zFS aggregate, the version 1.5 aggregate. The current zFS aggregates are version 1.4 aggregates. The main purpose of the version 1.5 aggregate is to support a new directory format (extended (v5) directory) that will scale better when the directory contains many names (over 10,000). Since the format of a new directory is different in a version 1.5 aggregate, zFS provides toleration APAR OA39466 to cause a mount of a version 1.5 aggregate in an earlier release to fail. Earlier releases cannot access extended (v5) directories or version 1.5 aggregates. In order to control the transition to the new format directories, extended (v5) directories can only be created in version 1.5 aggregates. To create or change to a version 1.5 aggregate, you must explicitly request it. By default, aggregates created in z/OS V2R1 are version 1.4 aggregates. You should only create or change to a version 1.5 aggregate if you are sure you will not run releases prior to z/OS V2R1. Over time (possibly several releases), most zFS aggregates will be version 1.5 aggregates. IBM® is likely to then change the default to version 1.5.

zFS toleration APAR OA39466 applies to z/OS V1R12 and V1R13.

zFS recommends that you should begin using the new zFS batch utility program IOEFSUTL. It contains all the function of the zFS format utility (IOEAGFMT) and the zFS salvage utility (IOEAGSLV). IOEFSUTL supports both version 1.5 aggregates and version 1.4 aggregates.

Beginning with z/OS V2R1, the batch utility ioeagfmt requires that the ZFS PFS be active.

New IOEPRMxx configuration options control what version an aggregate is formatted as by default (format_aggrversion), whether a version 1.4 aggregate is changed to a version 1.5 aggregate on mount (change_aggrversion_on_mount ) and whether directories are converted to extended (v5) directories as they are accessed (converttov5).

A new MOUNT PARM controls whether a particular zFS aggregate's directories are converted to extended (v5) directories as they are accessed (CONVERTTOV5).

zFS has enhanced its support for the backup change activity flag in the VTOC (D1DSCHA in the Format 1/8). This flag indicates whether a backup of the file system is needed (that is, data has been modified in the file system since the last backup).

Beginning with z/OS V2R1, the default value for IOEPRMxx configuration options user_cache_size, meta_cache_size, and metaback_cache_size are now calculated based on the amount of real storage in the system.

Beginning with z/OS V2R1, the default will be to create zFS auditfids during aggregate formatting.

A new configuration variable was added to IOEFSPRM: user_running_hangdump.

To help alleviate the version 4 large directory performance problem before migrating to version 1.5 aggregates, zFS will allow the creation of new Large Fast Lookup Cache buffers above the bar (64 bit storage) that will be used to fully cache large directories. This is done with a new IOEPRMxx configuration option flc. This option will only be valid in releases z/OS V1R13 and V2R1. It is available on z/OS V1R13 in APAR OA40530.