zFS-enhanced sysplex-aware support

Beginning in z/OS® V1R13, zFS provides enhanced sysplex-aware support. When a zFS read/write file system is mounted sysplex-aware in a shared file system environment where all systems are running z/OS V1R13 or later, zFS can directly read and write zFS data from all of the V1R13 or later systems. If both the owning system and the requesting system are running z/OS V1R13 or later (and the file system is sysplex-aware), zFS directly accesses the file system. While zFS data is directly read and written, zFS metadata is normally read and written through the zFS owning system (SY2 in Figure 1). In some cases, zFS metadata can be directly read.

Figure 1. zFS read/write file systems sysplex-aware and non-sysplex aware on a file system basis. FS2 is being directly accessed from all z/OS V1R13 or later systems.

There are some cases when an application running on a system (SY1) that is doing direct I/O can be affected by problems on the zFS owning system (SY2) such as a failing system or having I/O failures on the owning system during metadata updates. The application can also be affected if it needs to traverse a higher level directory contained in a file system that is owned by the failing system.