Someone could (or try) explain to me this strange thing???

I looked for disk space with unix command df :
> df -h
File system          Size  Occ   Free   %Occ  Mount       
/dev/sda6             1,1T  135G  920G  13%    /var

But when I read "BackupPC : Host Summary.

47 full backups of total size 1384.71 Go (prior to pooling and compression)
72 inc backups of total size 65.73 Go (prior to pooling and compression)

I don't unterstand what's happen, I must have a full device, but only 135Go seems to be occupated.

Someone have an idea !!!

Benoit BELY