Something wrong here either SACORP or my pc that my description doesn't appears.
Thats why trying to attach txt file if works.

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Hi All,

I hope there is no way at filer side to check used data size within a LUN. If there is a way then please tell me how we can check used data size within at LUN at filer side.

But if there is now way then I have one concern :

Based on "Block Access Management Guide for iSCSI and FCP.pdf" doc which talks about fractional reserve concept and says that if fractional reserve for a volume having LUN inside is 100% and then if snapshot is taken then it reserves out of volume available space equal to used size of LUN. 

So my question is how Data ONTAP knows used space within a LUN and if its possible some how then why don't have any CLI command or other way to check it out.

Please provide your understanding on it.

Regards,

Raju