It may be necessary to know exactly what a lun being presented from the array  is called within the Filestore cluster. This can be tracked by using the Host LUN ID within the array and the Disk Serial ID within the NAS engine.

Log in to the array controller using the ISM gui and select the host group which maps the lun to the N8300 NAS engine. Note the numbers in the 'Host LUN ID' column.

Log in as the master user, either within the ISM gui or using the CLI.

With the CLI use the 'storage disk list detail' command to show information on the luns presented

n8300> storage disk list detail

Disk             Pool                             Enclosure      Size      Use%   ID                  Serial Number

====             =============================    ==========     ====      ====   ==                  ==================================

huawei-s5600-0_13 -                                huawei-s5600-0 20.00G    0.0%   HUAWEI:S5600:0:2    60022A110001BDC12F3C4EBA00000001

huawei-s5600-0_14 -                                huawei-s5600-0 20.00G    0.0%   HUAWEI:S5600:0:1    60022A110001BDC12F3C4C1800000000

huawei-s5600-0_15 -                                huawei-s5600-0 50.00G    0.0%   HUAWEI:S5600:0:9    60022A110001BDC13006ABF600000002

 Alternatively, using the ISM gui click on either 'Unused Disk' or 'Used Disk'