- Using Client based tools:
The most effective method of viewing LUN consumption from the client perspective is to use client-side tools such as Windows Explorer or UNIX 'du'.
Windows Disk Management can also be used to show the LUN size.
- Using Filer storage based tools:
If LUN is already in use and data has been written to the LUN:
Create a new volume, create a new LUN, and ndmp copy the old LUN data to the new LUN , and df -r.
Using the methods above will show the exact size of the consumed LUN space.
NOTE: The df -r command will effectively display the consumed LUN space as long as the following are true.
a. There is only 1 LUN within the volume.
b. There are no snapshots of the LUN within the volume.
c. Space reservations are turned off on the LUN.
Space reservations and Fractional reserve will affect the usage displayed.
LUN size displayed on the filer via df -r and client utilities may differ in size.
There are two distinctions in the way LUN space consumed can be viewed:
1. LUN Space can be viewed as Filer Storage Blocks consumed within the WAFL volume.
Due to the way some operating systems format the LUN, the filer will see the LUN as a sparse file.
2. LUN Space can be viewed as the amount of space consumed by the Client Operating System within the LUN.
This view displays the Operating System's view of amount of space consumed and LUN size.
Client operating systems may have data written to blocks within the LUN that is not actual user data.