It is rapid publishing articles which is running windows XP SP2 or later attempts to delete a file that is saved on a Unisys MCP file server. Basically it appears to the user in which the file has been deleted, but in fact, the file has not been deleted. A Windows computer which is running Windows XP SP2 or later (Windows Server 2003, Windows Vista, Windows 7) attempts to delete a file which is saved on a Unisys MCP file server. The MCP (Master Control Program) is the proprietary operating system of the Burroughs large systems which are include the Unisys Clearpath/MCP systems. The MCP was the first operating system which is manages multiple processors and the first commercial implementation of virtual memory, among numerous other advances.

When you attempting to delete a files on a Unisys MCP Server by using Windows Explorer on a Windows XP or later based computer, It appears to the user that the file has been deleted, (suppose, the file disappears from the Explorer window, or from the command prompt, no error is returned) but the fact is that, the file has not been deleted. The Windows SMB redirector client who receives an Access Denied error from the remote Unisys MCP Server and the reason is that the file is a read-only file. This is the expected and documented behavior for the SMB DELETE command when you want to delete a read-only file. But, the error is not passed back from the redirector to Windows Explorer; rather, the redirector returns a success. Windows Explorer and the Command Prompt both are act as if the file has been deleted because the redirector said that it had. But the fact is that the file was not deleted. Windows Explorer basically will check to see if the file is read-only, clear the read-only bit and attempt to delete it again, which would be successful in the problem scenario, or it would be return an error. The Command Prompt will basically return an error indicating which the reason for the failure is. The functionality fails, though; the reason is that the redirector never returns the Access Denied error.

Reproduce the issue

At first Setup a file share on a Unisys MCP server with a read-only file which is stored on this share. Then connect to the share from a Windows machine which is running an OS that is later than Windows XP SP2. Now attempt to delete the file. It will appear like that the file has been deleted, but if you refresh the Explorer view of the file share or execute a DIR of the folder at a Command Prompt then you will see that the file has not been deleted. If you want to resolve this issue then at first you must manually remove the read-only bit and then delete the file. If the read-only bit has been removed, then the file can be deleted as expected.