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NetBackup System Administrator’s Guide - Windows NT Server
3
• Class Priority. Use this attribute to control the order in which NetBackup
starts its backups. The client in the higher priority class is backed up
first.
There are also other attributes that are explained later in this chapter. In our
example, the general attributes are satisfactory for all clients and files so no
extra classes are required.
6. Create separate classes as necessary to maximize the benefits of
multiplexing.
Using multiplexing for slower clients that produce small backups is a
strategy for maximizing drive utilization. However, higher-performance
clients that produce long backups are likely to fully utilize drives and not
benefit from multiplexing.
7. Evaluate total backup times for each schedule and further subdivide your
classes to reduce backup times to an acceptable level.
Compute the approximate backup time by multiplying the speed of the
device by the amount of data in the backup. For example, if your backup
device transfers data at 800 kilobytes per second, it takes 0.7 hours to back
up 2 gigabytes.
The variable that is easiest to control here is the amount of data in the
backup. NetBackup imposes no limits on backup size, but try to keep
backups to less than 2 gigabytes. In addition to reducing backup time,
shorter backups mean usually mean less time to recover files that are near
the end of the backup.
In our example, it so happens that backing up
D:\User
,
D:\h001
, and
E:\h002\Projects
on mercury takes too much time so we create a new
class for
E:\h002\Projects
. This new class (S5) has the same
requirements as S1 but we can now back up
E:\h002\Projects
separately thus reducing backup time. The table below shows the final set
of classes.
In addition to reducing the backup time for each class, putting the files in
separate classes can reduce the total backup time for the server mercury.
NetBackup processes files within a file list serially and in the order they
appear in the file list. However, separate classes are backed up in parallel if
enough drives are available and the maximum jobs attributes are set to
allow it (“Number of Concurrent Streams” on page 73 provides an
explanation of maximum jobs settings that also applies to this discussion).
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
