STORE and TurboSTORE/iX Products Manual (B5151-90003)

Chapter 7 121
TurboSTORE/iX 7x24 True-Online Backup
Using TurboSTORE/iX 7x24 True-Online Backup
Sync Point at the Beginning of Backup
The sync point is always at the beginning of an online backup when only the ONLINE option
is used. A 7x24 true-online backup can also have the sync point at the beginning by using
the ONLINE=START option.
The main difference between these two types of backups is that an online backup (ONLINE)
requires all files to be closed at the sync point, while a 7x24 true-online backup
(ONLINE=START) allows users to access and modify their files, uninterrupted, throughout
the sync point and backup.
Why Use the Sync Point at the Beginning of a Backup?
Using the sync point at the beginning of a backup has the following advantages over using
it at the end:
Synchronizing at the start of a backup gives you better control of when the sync occurs.
It spreads the log data throughout the tape and therefore one is less vulnerable to
media errors.
It allows for faster recovery of partial restores, since sync at end requires RESTORE to
read the log files from the end of the last piece of media.
It allows for migration of files to earlier releases of TurboSTORE/iX, whereas sync at
end does not.
For example, scheduling the sync point at the beginning of the backup is useful when your
system is heavily used during the day, making performing backups then impractical. The
backup can be started at the end of the busy day shift, and run during the night. Since no
application shutdown is required, users, perhaps from other time zones, can continue to
access their files and applications uninterrupted.
Sync Point at the End of Backup
TurboSTORE/iX 7x24 True-Online Backup can also schedule the sync point at the end of
the backup using the ONLINE=END option. Using the options described in "Creating a 7x24
True-Online Backup (ONLINE)", you can schedule the sync point to occur at a fixed time,
or at the end of the backup. However, if you specify the sync point to occur at a certain
time, it does not occur until all files have been stored.
Why Use the Sync Point at the End of a Backup?
Using the sync point at the end of a backup has the following advantages over using it at
the beginning:
Synchronizing at the end of the backup creates a logically consistent copy of your data
at the time of the end of the backup.
It gives you the most recent copy of your data.
The backup media can be off the system and stored in a data safe before running a
"risky" application. If the "risky" application fails, you can recover your data at the
point just prior to starting the application.
All file changes occurring during the backup are logged and stored at the end of the