Welcome to this edition of the “CICS Spotlight.” This issue focuses on a file system that all CICS support folks use when implementing Web services—HFS. It appears IBM has delivered an additional facility to replace HFS—zFS. So, if you aren’t familiar with the new file facility, now may be the time to do some research. In addition, IBM Hursley has created a new Website for CICS folks, so be sure and check it out.
HFS vs. zFS
Customers who use Web services are no strangers to HFS, the file service used by Unix and CICS to support the correlating data and processes executed between the two platforms. Just when you think you’ve “mastered” the HFS files that need to be created and supported for these CICS processes, a new file system has been introduced to effectively replace HFS. Now’s the time to get up to speed on zFS, since it appears HFS is on the way out.
zFS Introduction
zFS was first introduced in z/OS Version 1.7 and customers were given the choice of which file system to use. Since many customers already had a sizable investment in HFS, there was no clear reason to move away, and many chose to continue using HFS, especially in their CICS systems. CICS systems programmers who used Web services had spent a great deal of time getting over the Unix learning curve and getting these HFS files in place.
Clearly, the introduction of an additional file system for Unix was a sign of what was coming, as IBM rarely introduces enhancements to the operating system or duplicate facilities for no reason. It’s become clear that zFS was introduced to become the “best practices” or “best of breed” for file systems within Unix. As noted in IBM documentation after the introduction of z/OS 1.7:
“Before z/OS V1R7, the HFS file system was the primary hierarchical file system. As of z/OS V1R7, you can use any combination of HFS and zFS file systems. Because zFS has higher performance characteristics than HFS and is the strategic file system, you should migrate your HFS file systems to zFS.”
The performance characteristics are probably what’s going to entice most customers to migrate from HFS to zFS, since the migration effort offers some degree of payback for the time spent. The reality, however, is that the migration will eventually need to be done, since, according to IBM when asked about whether the migration is required, the comment received was:
“No, but recommended because the action is planned to become a requirement in a future release. zFS is the strategic file system for z/OS UNIX and continues to be enhanced to provide superior performance, reliability, and data integrity.”
In the announcement of z/OS 1.9, no mention is made concerning withdrawal of support for HFS, but in most of the HFS documentation IBM states that the withdrawal of support is inevitable and could even come in the next release.
I’ve also been told that Hursley is working on updates to all installation and support publications for the next release (beyond TS V3.2) so that all references to HFS will be replaced with zFS. If that’s not handwriting on the wall, I don’t know what is.
Differences Between zFS and HFS
Probably one of the most dramatic differences between the two file types is that zFS files are actually VSAM Linear Data Sets. This could substantially change the process customers use to create and maintain data that’s typically stored in an HFS file. In addition, VSAM files must be managed differently than typical z/OS files, such as PDSE data sets or load libraries. IBM has created a great deal of documentation on zFS, including Redbooks and library publications, several of which I have included references to below for your review prior to migration.
Because IBM is encouraging customers to move from HFS to zFS, a new tool has been delivered that may help you with the migration. An official migration tool, BPXWH2Z, is provided with every release of z/OS starting with 1.7. This tool can simplify the process and get the project off the ground. Consult your z/OS systems programmer for documentation and assistance with the migration tool. A technical overview of the migration tool can be found at www.redbooks.ibm.com/abstracts/tips0647.html?Open.
Additional links for z/FS information can be found at:
· http://publib.boulder.ibm.com/infocenter/zos/v1r9/index.jsp?topic=/com.ibm.zos.r9.e0zm100/hfs2zfs.htm.
New IBM Website: Ask the Developers
There’s a new Website offered by the generous folks in Hursley. The link is http://masterterminal.wordpress.com/ and it’s titled The Master Terminal—All about CICS Transaction Server from those who produce and use it. It’s provided by the group of developers, change team members, and other Hursley folks who support the product and are therefore perfect sources of information. While IBMLink or ServiceLink are great places to ask for help, many customers don’t want to go through the formal Q&A process on those sites, or perhaps don’t have those services. This Website will enable you to ask CICS questions and get answers from the appropriate member of the Hursley team. Thanks, Hursley!
Summary
I hope some of the information shared in this Spotlight has been helpful. Thanks to all of you for your continued support.
