Today the client tell me. all database can not be backup. and give me an error. "Filegroup is full".
After i check . i found the correct resaon is backup device is not correct, the file or folder was be deleted.
The operating system returned error 21
(failed to retrieve text for this error. Reason: 15105)
to SQL Server during a read at offset 0x00000000120000 in file 'H:\Database\xxx.mdf'
System.Data.SqlClient.SqlError: Cannot open backup device 'C:\DATABASE\_shops.bak.2010-05-23-03-00-00-000.ADD'. Operating system error 3(failed to retrieve text for this error. Reason: 15105). (Microsoft.SqlServer.Smo)
The resion is the file is missing. the file or the folder has been delete .
原因是：数据库备份的文件夹不存在了。