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Daniel Arrondo Ostiz Thu, 02/23/2012 - 00:05
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Hi Muhammed,


When you say that WAAS is not caching, I guess you mean that the optimization achieved is much lower than without zipping the file. Am I correct?


If that is the case, then, I'm afraid it's the expected behavior. The cause for this is DRE


In general terms, the way DRE works is by caching small chunks of a file. Later on, when these chunks are seen again in the file (either in the same connection or subsequent ones), they will not be transferred through the WAN link and instead, a chunk identifier (very small) will be sent. The problem is that all compression algorithms work in a similar way, removing repeating parts of the file to make it smaller.


The result is that, any file that is encrypted/compressed has almost no repeating patterns in it, and therefore, even though DRE is applied, the reduction ratios are minimal, sometimes even getting to the point of making transfer even slower than without it.


As a general good practice, if you are using WAAS to optimized your data transfers, make sure that the files you are transferring are neither compressed nor encrypted. This way you will get the maximum optimization ratios out of WAAS.


I hope this answers your question


Daniel

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