libparted problem with moving data on partitions

[ben]

I am using libparted version 2.3.

If I move data with ped_device_write() I sometimes get errors in the moved data if the device has mounted partitions even though the data in another  

partition or free space. The ped functions don't return any errors. Is there a way to use ped_device_write() on a busy device safely or some better 

alternative? 

Thank you.