TrueNAS CORETrueNAS CORE Nightly Development Documentation
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Increasing iSCSI Share Available Storage

Expanding LUNs

TrueNAS lets users expand Zvol and file-based LUNs to increase the available storage that the iSCSI shares.

Expanding Zvol LUNs

To expand a Zvol LUN, go to Storage > Pools and click the next to the Zvol LUN, then select Edit Zvol.


Enter a new size in the Size for this zvol field, then click SAVE.


To prevent data loss, the web interface does not allow users to reduce the Zvol size. TrueNAS also does not allow users to increase the Zvol size past 80% of the pool size.

Expanding a File-Based LUN

To expand a file-based LUN, you need to know the path to the file. To find the path, go to Sharing > Block Shares (iSCSI) and click the Extents tab. Click the next to the file-based LUN and select Edit.


Highlight and copy the path, then click CANCEL

Go to the shell and enter truncate -s +size path/to/file where size is how much space you want to grow the file by, and path/to/file is the file path you copied earlier, then press Enter.


An example of the command could look like this: truncate -s +2g /mnt/Shares/Dataset1/FileLun/FileLUN

Lastly, go back to the extent in Sharing > Block Shares (iSCSI) and make sure the Filesize is set to 0 so that the share uses the actual file size.