barunpathak (5/6/2009)
1) Do I overwrite the same files everytime?
You can, but what if you need to restore an older backup, either because the newer one is corrupt (it happens) or because someone wants to see the data as it was 2 weeks back?
2) Can I overwrite tuesday's file with wednesday's file and so on?
Again, you can because diffs contain data since the last full, but again, what happens if you go to restore and the Wed backup is damaged, or someone deleted data on tuesday and you need to restore to get it back?
3) How about log files? These are probably I neeed to keep all the files since they run every two hours.
For logs, you need an unbroken chain of log backups to restore from. So if you need to restore to say Thursday 10am, you need the last full backup, the wed differential backup and all log backups since the wed differential. It's a good idea to keep at least back to the last fill, if you have space, to give yourself several options for recovery.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability