Contiguous Free Space / Defragment - any risk to data?

Hi All,

I just want some advice on a problem I am running into with our Clariion AX4.  I have very limited experience of working on EMC SAN's but im running into an issue when trying to bind new LUNs.

There is 600gb of free space but only 400gb of contiguous free space available.  Of course I need to try and allocate 600gb to a new LUN.

I have had a look online and come to the conclusion that we need to defrag the disk group in order to put all of the disk space together.  I have identified where I need to trigger the defrag but I am concerned about the impact of running the defrag.

Is there any risk to the data in the existing LUNs on the disk group or the performance?  I expect there to be an impact on performance but not sure what to expect.  The disk groups are all running production loads to need to be aware of the risks involved.

Any advice greatly appreciated.

Thanks in advance