Server 2012 There is not enough disk space errors, but there is!

I have a Dell PowerEdge T130 running Windows Server 2012 R with Perc H330 managing a RAID 1.   The RAID is broken into 2 partitions including a OS (C:) and DATA_DRV (E:).   There is currently 220 GB free on OS and 592 GB free on DATA_DRV.  

After coming back from a long holiday weekend, I find that I cannot create or move any files into the DATA_DRV without getting the error “There is not enough space on DATA_DRV”.    I do not get that error on the OS drive.  

Workstation applications that depend on data stored on DATA_DRV are opening “Read Only”

Last night’s backup failed with the following error:
Creating Snapshot set...
CreateSnapshotSet() failed(Error during asynchronous operation. HRESULT = 0x8004231f
(VSS_E_INSUFFICIENT_STORAGE)), trying to lock volume(s)...
Volume RECOVERY (2:) locked
Failed to lock volume OS (C:)
Error during asynchronous operation. HRESULT = 0x8004231f (VSS_E_INSUFFICIENT_STORAGE)

The event viewer showed the following error:
There was insufficient disk space on volume E: to create the shadow copy of volume E:.  Shadow copy storage creation failed.

I ran Vssadmin list shadowstorage.   The maximum for each volume is set at 10%.  The Used and Allocated space for all were 0%

I did a vssadmin list writers and all were listed as Stable with No error.

I have performed a full antivirus scan and an SFC.  

Any suggestions as to where to go next?