Support for type 30 SMF record

The type 30 SMF record provides accounting information. z/OS UNIX contributes to them, in part, by providing a count of the number of blocks that are read from file system disk blocks, or written to file system disk blocks, during each operation performed in a UNIX file system by a user or an application. The SMF30OFR and SMF30OFW fields of the SMF record contain these counts. The zFS PFS provides the count of blocks that are involved in these I/O operations to z/OS UNIX in the OSI control block fields readibc and writeibc.

Due to the aggressive caching that zFS does with the contents of the disk blocks, it is not possible for zFS to provide an exact count of actual I/O operations that are done by each user or application. Instead, zFS provides a weighted cost estimation of the number of disk blocks an operation could read or write. This method of counting the blocks is not the same as that used by HFS, so comparisons of HFS versus zFS file systems will not be accurate. This method of counting the blocks should be consistent enough to allow the comparison of two users or applications accessing the same zFS file system. This will be true even if the file system is mounted RWSHARE and accessed from two different systems that are sharing it.