Use qtrees to partition your FlexVol volumes overview
Qtrees enable you to partition your FlexVol volumes into smaller segments that you can manage individually. You can use qtrees to manage quotas, security style, and CIFS oplocks.
ONTAP creates a default qtree, called qtree0, for each volume. If you do not put data into a qtree, it resides in qtree0.
Qtree names must have no more than 64 characters.
Directories cannot be moved between qtrees. Only files can be moved between qtrees.
If you create qtree-level and volume-level shares on the same FlexVol or SCVMM pool, the qtrees appear as directories on the FlexVol share. Therefore, you need to be careful not to delete them accidentally.