User Guide

78 Server Operating System Administration Guide
Server Operating System Administration Guide
103-000148-001
August 30, 2001
Novell Confidential
Manual 99a38 July 17, 2001
How TTS Works
The Transaction Tracking System (TTS) can prevent data corruption by
backing out of incomplete transactions and keeping a record of backed-out
data.
TTS guarantees that all changes to a database file are either wholly completed
or not made at all. TTS follows these steps to track transactions:
1. When the application allocates a physical or logical record lock, TTS
infers that the application is making a transaction. At this point, if you
have flagged the file as transactional, TTS begins tracking the transaction
so that the transaction can be backed out if a failure occurs.
2. TTS makes a copy of the original data so the data can be restored if the
transaction fails. A copy of the data is placed in a file external to the
database. This external file contains all transaction backout information;
only the operating system uses it.
3. After the copy of the original data has been written to the backout file,
TTS writes the changed data to the database file.
4. TTS repeats Steps 2 and 3 for additional changes (a single transaction can
consist of a sequence of changes).
5. When all changed data has been written to disk, and the database
application releases physical and logical record locks, TTS infers that the
application has completed the transaction. TTS writes a record to the
backout file, indicating that the transaction is complete, and stops
tracking the transaction.
To learn how to enable and activate TTS, see “Enabling and Activating TTS”
on page 78.
Enabling and Activating TTS
In NetWare 6, TTS has three possible states:
 Disabled
 Enabled but inactive
 Active
The disabled and inactive states are similar in that TTS operations have no
effect. Only in the active state, do TTS operations have an effect.