gtpd1m0r | Database Reference |
File pool support is provided for external storage devices that use FARF addressing. Support is included for small/large/4K, single/duplicate records with various retention requirements. There are 10basic pool types, as follows:
Small, large, and 4K records are defined as 381, 1055, and 4095 bytes long respectively. Pool types SLT, SST, LLT, LST, 4LT, and 4ST contain single copy records in a partially duplicated file system and duplicate records in a completely duplicated file system. Pool types SDP, LDP, 4DP, and 4D6 are provided for systems with a partially duplicated file system and a requirement for duplicated file storage records.
Long-term file storage records can be maintained during an interval of time as determined by operational procedures. Short-term pools, however, are designed for quick turnover records. Maintain short-term file storage records for short intervals of time (in other words, the time required to complete a transaction with a customer). When returned by application programs, long-term addresses are batched to an online data file to be returned to the TPF system at a later time by recoup or pool directory update (PDU) processing. Short-term addresses are, however, immediately returned to the relevant pool for reuse.
Each basic pool type applies to a specific device and uses FARF addressing. Each group of pool types on a specific device is called a pool section. Each short- and long-term pool can have a maximum of four pool sections. For example, the following represents four pool sections for small, long-term records:
where A, B, C, and D represent the device type defined with the system initialization program (SIP). See TPF System Generation for information about SIP.
Pool sections can be broken up into noncontiguous areas on a device type. Each of these areas is called a pool segment.
For example, the small, short-term pool (SSTx) might consist of 2 pool sections, each with segments as follows:
Each directory set is initialized when needed and updated when short-term pool addresses are returned to those pool sections. Because short-term directories are recycled, they are not included in recoup and pool directory update (PDU) processing. When a short-term pool section is depleted, the relevant directory sets are again reinitialized and used one-at-a-time starting with the pool section's first directory. This is called recycling the pool section.