Today I faced a problem of restoring database backup, consist about 20GB, before a week, I restored backup simple and fast as usually, today it takes hours and hours to restore, what can be problem in here? I faced some errors like: FCD::Cannot open file..
OK Comment list getting a little long..... Can you confirm that the file does actually exists in the location you think it is? Could there be any other process accessing the file (NAS/disk/tape backups, anti-virus scans, etc)? Is the backup from the same server that it is being restored on or another server?
Based on the errors it looks like you are trying to restore to the root of the drives. Create folders on the drives to restore into and ensure that the SQL Server service has full NTFS access permissions.
From all the other comments it sounds like your RAID array is taking a hit. Is Drive C: a different array, possibly RAID 10, then you have another set of disks for D: and F:. When I first started reading your post I was thinking maybe you had a bad drive and the array was having to rebuild a spare, but with the errors you are getting trying to write to the disk makes me think you have bad sectors. I would recommend running a scan disk on the drive to rule that out. Are you pretty familiar with RAID and can look at the RAID Manager software to check for errors? If not get your systems guy to take a look. Windows Event Viewer might also contain some good information as to what is going on with the disk subsystem.