Free space of 3PAR is reduced after running tunesys

[RogerVI]

Hi,

We had a CPG with 8 SSDs of 920 GB (we also have FC disks). We recently added 4 additional SSD disks of the same size. After placing these additional disks to the system, the free space was 4356 GB (Figure 1).
Then we ran tunesys to the CPG (by the graphical console Action => Provisioning => Tune System, Tune CPGs ) and the free space was reduced to 3452 GB (Figure 2).

Why is free space reduced after running tunesys? I have the fear if I run the tunesys again the free space will be reduced even more.

Thanks in advance