Additional Setup
155
4
• You cannot use bandwidth limiting to load-balance active backups by
having NetBackup pick the most-available network segment. NetBackup
does not pick the next client to run based on any configured bandwidth
limits.
How Bandwidth Limiting Works
When a backup starts, NetBackup reads the bandwidth limit configuration and
then determines the appropriate bandwidth value and passes it to the client.
NetBackup computes the bandwidth limit based on the current set of active
backups on the subnet (if any) and the new backup that is starting. Backups
that start later are not considered. NetBackup also does not include local
backups in its calculations.
The NetBackup client software enforces the bandwidth limit. Prior to each
write of a buffer to the network, client software calculates the current value for
kilobytes per second and adjusts its transfer rate if necessary.
As the number of active backups increase or decrease on a subnet, NetBackup
dynamically adjusts the bandwidth limiting on that subnet. If additional
backups are started, the NetBackup server instructs the other NetBackup
clients running on that subnet to decrease their bandwidth setting. Similarly,
bandwidth per client is increased if the number of clients decreases. Changes
to the bandwidth value occur on a periodic basis rather than as backups stop
and start. This can reduce the number of bandwidth value changes that are
required.
Configuration
You enable bandwidth limiting by adding one or more
LIMIT_BANDWIDTH
entries to the registry on the master server. These entries let you designate
bandwidth values and the IP addresses of the clients and networks to which
they apply. For information on adding these entries, see “Bandwidth” on
page 489.
Rules for IP Address Ranges
The IP address ranges can specify individual clients or entire subnets. The
following are some specific rules on addresses:
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT