checkpoint occurs very often when vacuum full running

Hi,

Can someone explain the logic behind it ? I know that vacuum full isnt something recommended but I found out that whenever I run vacuum full on my database checkpoint occurs during that time every second ! well I know that VACUUM FULL duplicates the data into new data files and then it deletes the old data files. The writing the vacuum does, is it with the checkpoint process ? 

Is there any connection ?

Thanks.