Online Data is Different from Backup: Already compressed and very few duplicates
A relatively small number of file types are driving the explosion of digital content. These are files like Images and Video (JPEG, MEPG, TIFF, GIF, PNG), Compound Documents (zip, email, HTML, Web Pages, PDFs) and Microsoft Office (Powerpoint, Word, Excel, Sharepoint etc.).

The majority of these files are already compressed by their applications. Generic compression will not work on these already compressed files. File aware optimization techniques can reduce the space taken on up by these files by as much as 90% or 10:1.

Online data is also different from backup data. Backups contain a lot of exact duplicates. Online data has few exact duplicate files but a lot of similar files. Techniques like generic compressors or block level sliding window dedupe don’t work well on compressed data and similar files with encoding that removes the effectiveness of dedupe. These techniques result in 10-30% reduction on non-text data. The Ocarina file-aware optimization produces impressive results reducing already compressed compound files by 50-80%.