Rsync not same size



I have seafile server, every day, i use rsync to copy data to another server with this command
rsync -avz --delete-after -L -e ‘ssh -p xxx’ /opt
But the size of data is not the same, in the folder name blocs
On seafile server
du -hs blocks
593G blocks
On server copy
du -hs blocks
810G blocks
I have deleted folder blocks on server copy and launch rsync, but its same
Can you tell me why i have 217 GO more

Sorry for my english
Thank you