When you select "Acceleration" in a policy you see a section for WM Reduction Type. It has 3 options:
Disk - means traffic is accelerated and reduction is seen by storing data on the local Exinda. Whenever that data is re-requested it is provided from teh local Exinda's disk instead of going out to the WAN and grabbing it from the server. This is the same as standard 'deduplication'.
Note that when the Exinda is performing logic to determine whether or not the file requested is one that is in the file, it involves computation based on the data in the file. It allows for small changes in the file to be accepted, but if large amounts of the file are different, it is counted as a separate file and will have to be redownloaded and saved. This will include files that are encrypted or even potentially signed by an encryption key that is unique to a server-client communication. Sometimes encryption keys are set up per session (called 'session keys') which even means that the same file requested at different times will have a different session key and will be encrypted differently. Sometimes a file will be on a central repository and encrypted with a unique repository-client key, so if multiple clients download the same file, they will be encrypted differently. There are varying other ways that this can happen.
Compression - Exinda uses compression algorithms to compress the data packets hence making them smaller in size when it passes through the WAN link. Hence saving on LAN vs WAN data. If a file is already heavily compressed (for example, JPEGs are heavily compressed vs RAW image data; JPEG compression, called DCT Compression, is some of the most powerful compression) then additional compression of the file might not be physically possible. However, it will still attempt it on all files passing through.
None - In this method you will not see any reduction except for SMB. LAN = WAN. Traffic will go faster because TCPad will increase windows size.
Without selecting the option "acceleration" and simply optimizing traffic, Exinda will not accelerate the traffic hitting that policy, it will only optimize it based on the QOS config.
Note- WAN Memory cannot work if TCP Acceleration service is off. TCP Acceleration is the heart of Exinda's application acceleration technology.