Getting rid of excess Documentum thumbnails

OpenText Documentum comes with a number of default settings that are not appropriate for most projects and can even cause problems when applied to a production system unchanged. One of those settings concerns thumbnails.

Documentum xCP is a great tool for creating Case Management applications using no code. It includes a viewer that can show your documents alongside their metadata and other relevant process information. Great stuff! The way that this viewer shows your documents can have some consequences however.

The xCP viewer can show documents of any file format by converting the pages of the document into images called thumbnails and then displaying the thumbnails in your browser. There are large thumbnails that are displayed in the main viewer window. There are also small thumbnails that are shown in the viewer’s page navigation bar on the left. All these thumbnail images that are generated are stored in Documentum with the document as renditions. Once the thumbnails have been generated, the next time you view the document the viewer only has to retrieve them.

An xCP application displaying a document

To make the xCP Viewer display your documents even faster, Documentum can be configured to generate the thumbnails as soon as you upload a new document.

Now here is the downside that can cause problems for your system. Documentum has a default setting that will enable automatic thumbnail generation for all documents in your system. Though the idea sounds nice at first, it means that a number of extra renditions will be added to every version of every document in you Documentum system, even if no one is going to look at the document using the xCP Viewer. All these renditions take up extra disk space. A LOT of extra disk space. The generated thumbnails can take up more space than the original content files, so your space requirement for content files will be 2x to 3x as much as needed for the original content. If you have millions of documents with terabytes of content files, you will need a serious budget increase just to store all the thumbnails.

Fortunately there are several ways to improve this situation. To start with, you can disable the default configuration and enable automatic thumbnail generation just for the document types and content types that will be displayed in the xCP application. This will reduce the number of useless thumbnails that are generated.

You can also turn off the automatic thumbnail generation altogether. In this case the xCP Viewer will generate the thumbnails it needs when it displays a document. This will take a second or so, but will save enormously on the storage needed for the thumbnails. The only downside is that the page navigation on the left side of the viewer does not work in this configuration. the xCP Viewer does not generate the small thumbnails needed for the page navigation. It only generates the main thumbnails.

At Informed Consulting we created a solution that improves on this in 2 ways:

-        A small xCP custom module that generates the small thumbnails for the xCP viewer

-        A custom job that deletes old thumbnails that are no longer needed

With these improvements we’ve cut the diskspace needed for thumbnails by 95% without losing any functionality in the xCP Viewer.

If you’re struggling with a Documentum project, contact us, we’ll be glad to help.