HP Integrity NonStop J-Series - Manual (Page 57)

Configuring Automatic Transaction Processing
HP NonStop AutoTMF Software User’s Guide—429952-017
4-9
Audited File Creation
Audited File Creation
Some programs create files, but the files are not audited. AutoTMF allows you to
configure file names that will be created automatically as audited files.
Audited File Renaming
Attempts to rename a file while the file is audited are rejected by the file system with an
error. Each audit record contains the name of the disk file being updated, so renaming
a file can make backout operations fail.
AutoTMF can rename audited files by performing a complex series of open, close, and
alter operations. A file that is opened by other processes cannot be renamed.
Handling Null Records in Entry-Sequenced
Files
Records can be inserted into an entry-sequenced file but they cannot be updated.
If the file is not audited, all inserted records are written to the file. Programs expect to
find a valid and complete record when reading the file.
If the file is audited and if a transaction is aborted, any non-committed record is
removed from the file and a null record (a zero-length record) is inserted in the non-
committed record’s place.
In many cases, a null record will cause problems for a non TMF-aware legacy program
because the program is not expecting to read zero-length records.
AutoTMF can hide the existence of null records in an audited entry-sequenced file by
discarding the records instead of returning them to the programs.
Reading Through Locks
Normally a READ or READUPDATE operation requires that the record being accessed
is not currently locked. However, since the operation does not lock the record, nothing
prevents concurrent access to the same record by multiple processes.
AutoTMF does not provide automatic transactions for non-locking operations like
READ. Normally, no transaction is required, but if a process performs a READLOCK
followed by READ operation on the same record, an error or deadlock may occur.
Note. The NonStop RDF product replicates the creation of an audited file on the backup node;
the NonStop RDF product does not create a file on the backup node if a file is created as
unaudited and is later altered to be audited.
Note. The NonStop RDF product does not replicate the rename of an audited file on the
backup node because the rename operation is not audited.