HP NonStop G-Series - Manual (Page 68)

Usage Guidelines
HP NonStop AutoTMF Software User’s Guide—429952-014
5-2
Auditing Unstructured Files
In a mixed NonStop AutoTMF software and application controlled transaction
environment, you must specify to NonStop AutoTMF software which files are managed
by NonStop AutoTMF software and which files are managed by the application. To
insure that NonStop AutoTMF software generates transactions for only for newly
audited files, proceed as follows:
1. Create a list of all the files that are newly audited.
2. Set the global parameter ATMFCOMMONTX to OFF.
3. Configure the new audited files as COMMONTX or SEPARATETX.
The choice of COMMONTX or SEPARATETX is determined by concurrency
requirements. In most cases, configuring the newly audited files to be managed
under one common automatic transaction (COMMONTX) will yield the desired
results. Knowledge of the access patterns and thorough testing will determine if a
particular file must be configured to be accessed under its own transaction
(SEPARATETX).
Failure to configure the newly audited files properly can lead to deadlocks and other
unpredictable errors.
Auditing Unstructured Files
Transactional applications rarely use audited unstructured files, but you may wish to
audit them for replication and file recovery. NonStop AutoTMF software supports
automatic transactions for accessing unstructured files. However, practical limitations
restrict the use of audited unstructured files.
Object Files
Auditing object files is impractical. When an object file is used for the first time (or the
first time after a cold load or a move or duplication), the operating system updates
external references, thereby modifying the file. Because the operating system does not
use transactions (automatic transactions cannot be generated in the operating
system), the update and process execution will fail. Thus, an audited object file is
unusable.
Edit Files
Although automatic transactions work with audited edit files, auditing edit files is
impractical. Common editing operations on an edit file move the end-of-file (EOF)
backward, but roll-forward processing of TMF (as well as HP NonStop RDF replication)
does not move the EOF backward. Because edit files store an internal directory pointer
at the last word before the EOF, an incorrect EOF makes the file unusable.
Unstructured Data Files
An unstructured data file can be audited. Moreover, if the end of file (EOF) is not
moved backwards, the EOF can be rolled forward or replicated. The PURGEDATA