Using the z/OS HFS to zFS migration tool

You can use the ISPF-based BPXWH2Z tool to migrate HFS file systems to zFS file systems. It has a panel interface that enables you to alter the space allocation, placement, SMS classes and data set names. With this tool, you can:

Migrate HFS file systems (both mounted and unmounted) to zFS file systems. If the HFS being migrated is mounted, the tool automatically unmounts it and then mounts the new zFS file system on its current mount point.
Define zFS aggregates, using the default settings, to be approximately the same size as the HFS. The new allocation size can also be increased or decreased.
Have the migration run in TSO foreground or z/OS® UNIX background.

The number of storage blocks needed to store a zFS file system might not be exactly the same as the amount needed for HFS. For example, starting with z/OS V1R13, zFS uses 8K blocks to contain small files; however, HFS uses 4K blocks. In this case, some HFS file systems may need additional storage (possibly twice as much) when they are migrated to zFS. For more information about migrating data from HFS to zFS, see z/OS Migration.

Note that when BPXWH2Z creates new zFS aggregates, you can control whether it creates version 1.4 aggregates or version 1.5 aggregates. The default is to create version 1.4 aggregates. You can change this default by specifying format_aggrversion=5 in your IOEPRMxx configuration options file before IPL or by dynamically changing the option by using the zfsadm config -format_aggrversion 5 command.