netgear redynas rn2120v2 - inactive volume

thanks for every thing..

I have some questions about the same problem:
The volume has 4 hard disks and each size is 8TB .. One of them is spare and the rest used by raid5 .. The volume has been hidden to LUN1 size 8TB, LUN2 2TB and LUN3 2TB
And size of the final volume is just over 14TB .. The size of the data that i copied to the volume does not exceed 2TB on LUN1 and less than 1.5TB on LUN2 ..
If the size of the stored data does not exceed 4TB ..
Now why do you say there is no free space for file system errors?
Question 2: What do you mean by leaving free space for file system errors and where?
The third question: Is if the number of files is too large as we have. Does it have an effect?

Question 4: When the snapshot is activated, the LUN becomes protected .. How can I allow users to write and read from it?
Where this process lasted for a whole day Because the number of files is too large.

finally
If the file count is too large about 30 million files per 1TB? What do you recommend..

Thanks again..