orchadmin diskinfo Vs df -m

[videsh77]

Hi

After I did 'orchadmin diskinfo -a' it showed information for all nodes. In this information it had displayed total diskspace. But the same is not matching with if I check using df command on unix. df command is showing more diskspace is allocated for node than shown by orchadmin.

Is there any reason, why orchadmin should show less diskspace than reported by Unix?