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There are two important considerations when planning a backup schedule:
There are two ways to perform a system backup. A full backup
copies all files stored in your system whether or not any of the
information in them has changed since the last backup. A partial,
or incremental, backup copies only the files that have changed since
the last full backup. This can be done with the DATE parameter of the
STORE command. A well-planned backup schedule combines
both methods. It usually calls for a full backup once a week and
a partial backup each remaining workday. If you follow such a schedule, you
would lose no more than 24 hours worth of information should the
system experience problems.
Your requirements for recovery time should also be considered.
Although it takes less time to make partial backups of your data
between full backups, it also takes longer to restore them, should
you need to. When restoring from partial backups, the last complete
full backup must be restored first. Then, each subsequent partial
backup must be restored. This is in contrast to spending more time
each night on a full backup, but only needing to restore files once.
You should examine your recovery time needs and expectations before deciding
on a backup strategy.
Figure 2-1 "Sample Backup" shows a sample
backup schedule that combines both full and partial system backups.
Figure 2-1 Sample Backup
It is best to perform backups at a time when people are not
normally using the system. Often, system administrators choose to
perform backups at the close of the workday or later in the evening.
It is also a good idea to schedule the backup for the same time
every day so users know when to expect it and can plan ahead.
Be sure to schedule enough time for each backup. Full backups
take more time and more media than partial backups. Performing a
partial backup a day or so after a full backup takes less time and
less backup media than a partial backup performed almost a week later.
As the week progresses, users will have modified or added
more files since the last full backup, and more new information
must be duplicated. If you perform a full backup on Friday, the
first partial backup on Monday may take only one tape, for example,
and not much time. By Thursday, however, the day before the next
scheduled full backup, a partial backup requires several tapes,
for example, and considerably more time, but still less than a full backup.
The TurboSTORE/iX 7x24 True-Online Backup ONLINE option allows you to
back up critical data and applications that need to be available at all times.
Using just the ONLINE option allows users to access files
after a short period of inaccessibility at the beginning
of the backup. However, using the new ONLINE=START or
ONLINE=END options, users can continue to access files, uninterrupted,
throughout the backup.
Refer to Chapter 6, "STORE and TurboSTORE Command Options," for information on
using the ONLINE option only, or Chapter 7, "TurboSTORE/iX 7x24
True-Online Backup," for information on using the new ONLINE=START and
ONLINE=END options.
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