Isilon Smartquota directory accounting size

Hi Gurus，

I have a 5 nodes F210 Isilon cluster with default 2d:1 protection. 

Question1:

I created a NFS export /ifs/testone/test3 and set SmartQuota on it with "File system logical size" quota accounting type.   After creating a directory "12345" under /ifs/testone/test3, Smartquota reports 23B usage.    If direcotry name is "123456", Isilon reports 24B usage. Anyone could help to clarify how this number comes from? 

Question2:

After creating a file in Linux using CLI "echo a > 2ByteFile", SmartQuota reports 8.03KiB usage.  Where does this 0.03KiB from? Should it be 8KiB?   Becasue Isilon Smartquota syas  File system logical size is "Physical size minus metadata and protection overhead".

Thanks in advance!