Determine Where to Store Updates

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server Update Services

Although metadata that describes what an update is useful for is stored in the WSUS database, the updates themselves are not. Think of updates as being logically divided into two parts: a metadata part that describes what the update is useful for, and the files required to install the update on a computer. Metadata includes end-user license agreements (EULAs) and is typically much smaller than the size of the actual update. Update storage is described in this section.

You have two choices for where updates are stored. You can store updates on the local WSUS server or you can store updates on Microsoft Update. The result for either option is outlined in the following sections. If you have multiple WSUS servers chained together, each WSUS server in the chain must use the same update storage option. These options are selected during the setup process, but can also be changed after installing WSUS. See Configure Advanced Synchronization Options for step-by-step procedures.

Local Storage

You can store update files locally on the WSUS server. This saves bandwidth on your Internet connection because client computers download updates directly from the WSUS server. This option requires enough disk space to store the updates you intend to download. There is a minimum requirement of 6 GB of hard disk space to store updates locally, but 30 GB is recommended. Local storage is the default option.


The 30 GB recommendation is only an estimate based on a number of variables, such as the number of updates released by Microsoft for any given product, and how many products a WSUS administrator selects. Although 30 GB should work for most customers, a worst-case scenario might require more than 30 GB of disk space. If that should happen, "Windows Server Update Services Operations Guide" offers guidance on how to recover. "Windows Server Update Services Operations Guide" is available on the Microsoft Web site for Windows Server Update Services at

Remote Storage

If you want, you can store update files remotely on Microsoft servers. WSUS enables you to take advantage of Microsoft Update for the distribution of approved updates throughout your organization. This is particularly useful if most of the client computers connect to the WSUS server over a slow WAN connection, but have high-bandwidth connections to the Internet, or if you have only a small number of client computers, as shown in the following illustration.

In the scenario in the Clients Downloading Approved Updates from Microsoft Update illustration, you configure WSUS so that client computers download updates from Microsoft Update. When you synchronize the WSUS server with Microsoft Update, you get only update metadata, which describes each of the available updates. In this configuration, the files that install updates on client computers are never downloaded and stored on WSUS.

You still approve updates to client computers on your network as usual, but when it comes time for clients to obtain the actual update, each client connects to the Internet to download it from Microsoft servers. These are the same servers Microsoft uses to distribute updates to the public. Although your clients obtain updates from Microsoft over the Internet, you still make the decisions about which updates are approved for distribution. The benefit of this scenario is that the distributed clients do not have to use the slow WAN connection to download updates, because WSUS only distributes approvals over the WAN link.