Operation System error 665 with VLDB backup (The requested operation could not be completed due to a file system limitation)
This error usually means that NTFS cannot add more fragments to the file being written to. Normally, this happens for CHECKDB sparse files but it could happen to any file. It is not sparse file specific.

I suspect your NTFS volume is already heavily fragmented. If there are many free space holes NTFS is prone to create many small fragments for new files. I have just seen a 16GB paging file with 120,000 fragments that was created on such a volume.

There is no way to tell NTFS to allocate more smartly. (Subjective note: NTFS is really stupid when it comes to allocating files. Many simple improvements come to mind but no investment is being made.)

Use a defrag tool that compacts the drive and removes holes. O&amp;O Defrag can do that for example. Of course you can manually compact by recreating the partition. But I don't know how realistic that is at your storage sizes.


  I also saw some references to file fragmentation and I see that these drives show 0% percent.


But the free space could be fragmented. That's where new data goes.