Backup performance varies based on the specific network environment in which NetWorker operates, in addition to NetWorker settings. Several factors external to NetWorker enter into performance calculations, including CPU speed, speed of data storage devices, the limitations of the network, and the volume of network traffic.
Within Legato NetWorker, you can tune performance by changing the following attributes:
This attribute in the Server resource sets the maximum number of savestreams that NetWorker allows to arrive at the server at one time. The maximum parallelism value is determined by the version of NetWorker you purchased.
This attribute in the Devices resource sets the number of save streams that a storage device can manage and multiplex to a volume. Use this attribute to maximize the performance of each device.
You can increase backup speed by setting NetWorker to multiplex (or interleaf) data on a storage device. That is, data from more than one save set can be written to a single storage volume, and data from one save set can be spread across multiple volumes. (Each save set that is multiplexed must, by definition, belong to the same pool of storage volumes.) Multiplexing optimizes and distributes the flow of data from multiple clients to all the storage devices that are available to NetWorker.
At recover time, performance can suffer because the data from one save set may have been written to several volumes.
Legato NetWorker maintains the integrity of each save set's data through a function that codes and tracks data by a save set identification number (
SSID). The extent of multiplexing that can occur on any storage device is defined by the device's value for Target Sessions.
It is often more efficient for NetWorker to multiplex multiple save sets to the same volume than to write each save set to a separate device. For this reason, NetWorker attempts to assign to each device a number of save sets up to the target value of sessions before assigning a save set to the next device.