Migration Zimbra 6.0.8 to 8.0.6 the problem is big file

Migration Zimbra 6.0.8 to 8.0.6

Hi,

i have zimbra 6.0.8 ubuntu 8.0.6 server and i exported the migration file and moved to the new server zimbra 8.0.6 ubuntu 12.04

and i am trying to import and installed zextras after installation i started import . but my exported file is 270 GB when i try to import the file is getting 1.6 TB and my storage size finished. i have just 1 domain and 3571 accounts . i tried 2 times .
The stored folder is 270 gb in old server but the new server the same file is bigger than 1.6 TB also it gives error cause of the there is no space on the storage .
What is the problem or what am i doing wrong .