Choosing a cache folder for thumbnails and previews

30. April 2025

Table of Contents

Why the cache folder is important

Index Manager creates and stores a low-resolution copy of the thumbnails and previews that it serves to the clients. This helps speed up the system since the server does not need to generate a new thumbnail and preview the next time a client requests a file that is in the cache. Caching is a major factor in optimizing system performance and a large cache stored on a fast local drive (with a large disk cache) is the key to building a responsive, high-performance Fotoware system.

Choosing a cache folder and the maximum cache size per index

To change the default cache folder, open Index Manager Settings and go to the General node.

In the Cache folder field, select a new folder. We recommend placing the cache folder on the fastest available local drive. NEVER store the cache on a network volume - it needs to be on a local disk.

Max cache size per index: This setting controls the maximum size of each index cache in megabytes. The cache can grow larger than the limit set here on a daily basis, but it will be reduced to the set size during the scheduled index optimization at which point the oldest cached items will be removed. Since caching is so crucial to maintaining solid system performance, consider storing the cache folder on a disk with plenty of available space to allow the cache to expand.

For more information about caching and its effect on system performance, see How Index Manager caching mechanisms work.

Cache folder recommendations

The cache folder should be placed on the fastest possible local disk, with plenty of available space to limit file fragmentation. Thumbnails generated by Index Manager use some 10-15Kb each, while each preview typically uses 100-150Kb.
The Index Manager process account set in Operations Center Settings must have access to read and write to the cache folder.
The index cache may grow beyond the size limit that you set in the configuration but will be reduced during index optimization.
If you find that the log frequently reports that the cache size limit has been reached and cache warming has stopped, you may need to increase the size of the cache folder.

Changing the location of an existing cache folder

When running FotoWeb on Internet Information Services (IIS), after changing the cache folder in FotoWeb you also need to update the virtual directory for the cache folder in IIS to the correct location. This can be done in the IIS management console.

Caching and Color Management

When Index Manager creates thumbnails and previews for the image cache, it will honor the ICC (International Color Consortium) profile that is present in the file. However, if the image does not have an embedded ICC profile, Index Manager will assume that the picture should be rendered with sRGB (standard Red Green Blue). This will have a negative impact on the thumbnail quality if the pictures are in Adobe RGB even if they are not tagged with that profile.