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You configure all of these features by creating security policies and adding WAN Optimization, web caching, and proxying to them. These same security policies can also include security profiles that apply UTM and NGFW features to WAN Optimization, web caching, and explicit proxy traffic.

Toggling Disk Usage for logging or wan-opt

Both logging and WAN Optimization use hard disk space to save data. For FortiOS 5.4 you cannot use the same hard disk for WAN Optimization and logging.

  • If the FortiGate has one hard disk, then it can be used for either disk logging or WAN optimization, but not both. By default, the hard disk is used for disk logging.
  • If the FortiGate has two hard disks, then one disk is always used for disk logging and the other disk is always used for WAN optimization.

On  the FortiGate, go to System > Advanced > Disk Settings to switch between Local Log and WAN Optimization.

You can also change disk usage from the CLI using the following command:

configure system global

set disk-usage {log | wanopt}


note icon The Toggle Disk Usage feature is supported on all new "E" Series models, while support for "D" Series models may vary.

Please refer to the Feature Platform Matrix for more information.


caution icon Changing the disk setting formats the disk, erases current data stored on the disk and disables either disk logging or WAN Optimization.

You can configure WAN Optimization from the CLI or the GUI. To configure WAN Optimization from the GUI you must go to System > Feature Select and turn on WAN Optimization.

note icon Remote logging (including logging to FortiAnalyzer and remote Syslog servers) is not affected by using the single local hard disk for WAN Optimization.

Enabling WAN Optimization affects more than just disk logging

In addition to affecting WAN Optimization, the following table shows other features affected by the FortiGate disk configuration.

Features affected by Disk Usage as per the number of internal hard disks on the FortiGate
Feature Logging Only
(1 hard disk)
WAN Opt. Only
(1 hard disk)
Logging & WAN Opt.
(2 hard disks)
Logging Supported
Not supported Supported
Report/Historical FortiView Supported Not supported Supported
Firewall Packet Capture (Policy Capture and Interface Capture) Supported Not supported Supported
AV Quarantine Supported Not supported Supported
IPS Packet Capture Supported. Not supported Supported
DLP Archive Supported Not supported Supported
Sandbox DB & Results FortiSandbox database and results are also stored on disk, but will not be affected by this feature.

Distributing WAN optimization, explicit proxy, and web caching to multiple CPU Cores

By default WAN optimization, explicit proxy and web caching is handled by half of the CPU cores in a FortiGate unit. For example, if your FortiGate unit has 4 CPU cores, by default two will be used for WAN optimization, explicit proxy and web caching. You can use the following command to change the number of CPU cores that are used.

config system global

set wad-worker-count <number>



The value for <number> can be between 1 and the total number of CPU cores in your FortiGate unit. Adding more cores may enhance WAN optimization, explicit proxy and web caching performance and reduce the performance of other FortiGate systems.

How this chapter is organized

The FortiOS Handbook chapter contains the following sections:

  • Inside FortiOS: WAN Optimization highlights the features and benefits of FortiOS WAN optimizaton.
  • Example network topologies provides an overview of FortiGate WAN optimization best practices and technologies and some of the concepts and rules for using them. We recommend that you begin with this chapter before attempting to configure your FortiGate unit to use WAN optimization.
  • Configuring WAN optimization provides basic configuration for WAN optimization rules, including adding rules, organizing rules in the rule list and using WAN optimization addresses. This chapter also explains how WAN optimization accepts sessions, as well as how and when you can apply security profiles to WAN optimization traffic.
  • Peers and authentication groups describes how to use WAN optimization peers and authentication groups to control access to WAN optimization tunnels.
  • Configuration examples describes basic active-passive and peer-to-peer WAN optimization configuration examples. This chapter is a good place to start learning how to put an actual WAN optimization network together.
  • Web caching and SSL offloading describes how web caching works to cache HTTP and HTTPS, how to use SSL offloading to improved performance of HTTPS websites, and includes web caching configuration examples.
  • FortiClient WAN optimization describes how FortiGate and FortiClient WAN optimization work together and includes an example configuration.
  • The FortiGate explicit web proxy describes how to configure the FortiGate explicit web proxy, how users connect to the explicit web proxy, and how to add web caching to the explicit web proxy.
  • The FortiGate explicit FTP proxy describes how to configure the FortiGate explicit FTP proxy and how users connect to the explicit FTP proxy.
  • FortiGate WCCP describes FortiGate WCCP and how to configure WCCP and the WCCP client.
  • Diagnose commands describes get and diagnose commands available for troubleshooting WAN optimization, web cache, and WCCP.