Actually we are using WLA but we cannot use the metrics you suggested. The metric value is somewhere arround 2e9 and 2e10 ms which I supposed are values far too high to be realistic. Do you have any explanation on this?
Not knowing what version of ECC/WLA or the microcode levels for the DMX/Symmetrix in question, but I have seen issues in the past around this particular metric that required a) a WLA patch and b) a microcode patch to resolve. I can not recall the exact details (microcode or WLA versions) but it was definitely at some level of ECC 5.2 with a DMX-3000 series array.
Also, I have seen cases where for LUNs with very low I/O this metric may present a garbage number. This is true for tools like sar as well - general rule of thumb that has worked for me in the past is to throw-out any service time statistics for very low I/O volumes.
So no concrete explanation - but two possible explanations. If you are very recent versions of code and have good sustained I/O then I'd suggest opening a case with EMC to get them to resolve the issue.
If this is control center 6.0 then there is a patch for the exponential issue. CC_4072 is the patch number and must be applied to all Symmetrix and SDM agents. The next day you should see the exponents be normalized