The nsr_exchange2010.exe is a small executable from EMC² that allows for Exchange 2010 backups & recoveries.
But the problem is that it uses VSS.
When the backup is interupted due to some issue (could be group abort or just OS/Exchange problem like a failed consistency check), the Exchange VSS writer will remain the status “State:  Waiting for completion” because the vss snap cleanups cannot finish.
A restart of the backup will fail with the message “backup-in-progress”.
Command to check the vss writer: vssadmin list writers
We can reset the VSS Exchange writer by restarting the Microsoft Exchange Information Store service or by killing the Store.exe proces.
The Exchange VSS Writer will switch to the status: “State:  Stable” and you will be able to restart the backup.