I have been experiencing some problems on since we implemented some changes on Saturday. The changes we made was to move the xyz database into the N drive. Even though this move was successful and the database has been working fine., another problem has evolved. This is all my database backup on the N: drive has since been failing.
M and N are raid drives on a clustered database server

xyz database backup failed on Sunday 16/02/03. The only way that I could get the database backup again was to move the backup to M drive.
Other User databases and Integration databases also failed yestarday 18/02/03. The only way that I could get the backup again was to setup the backup on the M Drive.
This morning, I also saw my abc database failed on the N drive.

They all have the same similar error message both in the event viewer and in the sql server error log.

In the sql server error log, the message is

"BACKUP failed to complete the command BACKUP DATABASE [abc] TO DISK = N'N:\Program files\Microsoft SQL Server\MSSQL\backups\abc\abc_db_200302181200.BAK' WITH INIT , NOUNLOAD , NOSKIP , STATS = 10, NOFORMAT"

and

"BackupMedium::ReportIoError: write failure on backup device 'N:\Program files\Microsoft SQL Server\MSSQL\backups\abc\abc_db_200302181200.BAK'. Operating system error 2(error not found)."

and

"Internal I/O request 0x13EEAA08: Op: Write, pBuffer: 0x15F20000, Size: 983040, Position: 48175616, UMS: Internal: 0x103, InternalHigh: 0x0, Offset: 0x2DF1A00, OffsetHigh: 0x0, m_buf: 0x15F20000, m_len: 983040, m_actualBytes: 0, m_errcode: 2, BackupFile: N:\Program files\Microsoft SQL Server\MSSQL\backups\abc\abc_db_200302181200.BAK"

The event viewer error message is

"18210:
BackupMedium::ReportloError:write failure on backup device 'N:\programfiles\Microsoft SQL Server\MSSQL\backups\abc_db_200302181200.bak'.Oper ating system error 2(error not found)."

and

3041

"Backup failed to complete the command BACKUP DATABASE abc to Disk = N'N:\Program files\Microsoft SQL Server\MSSQL\backups\abc\abc_db_200302181200.BAK" with init, Nounload, noskip, stats = 10, noformat"

What could be the reason why backup is failing on the N drive and not on M drive. Please help