In plone I have uploaded only 800 GB of data (mainly pdfs), it has occupied already 2 TB of hard disk space. Where exactly is the space being used up? I am using collective.documentviewer with its default settings. and plone 4.3. Are files stored by documentviewer changed to various image sizes ie Thumbnail, large image etc and stored in the blobstorage folder?
With collective.documentviewer, space is nearly doubled(or more) for every PDF.
In order for collective.documentviewer to do what it does, it converts each document into a series of images which are stored in addition to the original PDF. It creates 2 sets of these--one smaller size and one larger. It does this because the online viewer uses images to display the documents instead of the original PDF. Then, it also OCRs the document, stores that text and creates a local index of the text so it can be searched.
2TB for 800GB of PDFs is probably right.
来源：https://stackoverflow.com/questions/30752375/where-is-the-main-space-used-up-in-plone-file-upload