SQL Server has encountered the following error: operating system returned error 19 or Could not allocate space for object in database because the PRIMARY filegroup is full

SQL Server has encountered the following error:  

1.Error operating system returned error 19 

2.Could not allocate space for object in database because the PRIMARY filegroup is full

Possible Cause:

外接SAN/iSCSI Storage磁碟機，指派的可用空間超過Storage實際可用空間，作業系統看到的空間並非Stoage實際可用空間，當Storage空間不足，SQL Server就會出現以下錯誤訊息，導致疑難排解困難，因為作業系統或SQL Server所看到可用空間是足夠的，但卻出現空間不足訊息

例如:  另一種可能是VMware 超額分配可用空間

Dynamic Storage Provisioning / vSphere Storage Thin Provisioning 

Error Message:

Error 1:

The operating system returned error 19(The media is write protected.) to SQL Server during a write at offset 0000000000000000 in file 'N:\SQLData\xxxx2.ndf'. Additional messages in the SQL Server error log and operating system error log may provide more detail. This is a severe system-level error condition that threatens database integrity and must be corrected immediately. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.

Error 2:

Could not allocate space for object in database because the 'PRIMARY' filegroup is full.

Resolution:

1.從Storage端，增加磁碟擴充可用空間

2.從OS端，因為Storage端空間已經不足，即使OS端檔案總管看到還有可用空間，但仍然需要刪除一些檔案來增加更多可用空間。