Staging large files

The staging feature supports synchronization of the following types of files:

• Page attachments
• Files in media libraries

Compared with most objects in Kentico that support staging, files are often associated with large volumes of data. Processing and synchronizing the binary data of files can use up a considerable amount of memory on the servers and other network resources.

The system allows you to set limits on the size of files that are synchronized by staging. You can utilize such limits in the following typical scenarios:

Setting the maximum content and request size

Staging of files is restricted by the web application’s maximum request limits:

• Maximum request size – the default .NET limit is 4096 kB (approximately 4 MB), but the default Kentico web.config contains a global httpRuntime element with a much higher value that will usually not be exceeded.
• Maximum length of content in requests – the default limit is approximately 28.6 MB.

To adjust these limits for the staging service:

1. On the target server, edit the web.config file in the CMS folder of the web project.
2. Add a <location> element for the staging service into the <configuration> section and set the following attributes:
   • maxRequestLength (<system.web>/<httpRuntime> element). The value is in kiloBytes.
   • maxAllowedContentLength (<system.webServer>/*<security>/<requestFiltering>/<requestLimits>* element). The value is in Bytes**.

<location path="CMSPages/Staging">
    <system.web>
        <httpRuntime executionTimeout="2400" maxRequestLength="4096" />
    </system.web>
    <system.webServer>
        <security>
            <requestFiltering>
              <requestLimits maxAllowedContentLength="4096648" />
            </requestFiltering>
        </security>
    </system.webServer>
</location>

3. Save the web.config file.

Synchronizing files larger than the set value results in failure (the target server returns an HTTP status 404: Not Found error).

Limiting staging of media library files

To limit the maximum size of files staged from media libraries:

1. On the source server, edit the web.config file in the CMS folder of the web project.

2. Add the CMSMediaFileMaxStagingSize key into the <appSettings> section of the web.config. The value is in kiloBytes.

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    <add key="CMSMediaFileMaxStagingSize" value="102400" />
   
   
    

3. Save the web.config file.

The system does not synchronize binary data for media library files above the limit. Synchronization tasks for such files only transfer the database definitions of the media objects, without the actual files. You can find records of files not being synchronized in the Event log.

Synchronizing very large files

If you have staging enabled and work with extremely large files (typically around hundreds of MB, depending on the performance of your servers), you may encounter errors such as out of memory exceptions. The errors occur when the system attempts to process large volumes of binary data while preparing staging tasks for the file changes.

If you need to keep such large files synchronized between the servers in your environment, we recommend the following approach:

1. Store the files in a media library (i.e. not as page attachments).
2. Set up shared file system storage for the media library folder, and ensure that the storage location is accessible for all staging servers.
   • See Configuring custom storage for media libraries.
   • You can also use a custom file system provider, and map the media folder to a shared network location, Azure Blob Storage or Amazon S3 storage.
3. Limit the size of binary data that is synchronized as part of media library file staging tasks – refer to the Limiting staging of media library files section.

Staging tasks related to large files now only synchronize the database definitions of the media files. The large binary data is no longer processed or transferred, but is automatically available for all servers due to the shared file system.