Following is my current SQL Server raid configuration:
- Raid1 with log files ~ 500GB
- Raid10 with data files ~ 1TB
I would like to keep 3 day worth of daily full backup and hourly transaction log backup on the system so its easily accessible. So my question is where should I put theses backup file and why.
Personally I'd put them on a separate set of spindles that were not being used for SQL server tasks already.
And then I'd copy them to tape nightly. Assuming you do that step, then I'd say just a dedicated RAID 1 array or even a 'don't bother with RAID' single disk.
It doesn't really matter where you put your backup files. What does matter is that you have a copy of them on another server or storage device, so that when your SQL Server goes down and you need the backup, you actually have access to them.
If this is production data, then you should also ensure that you have off-site copies of the backups, thus eliminating the risk of data loss if the building burns down or some other catastrophic event happens.
If it's possible, I would recommend a separate volume for your backups in order to keep the backup I/O separate from your data and log I/O. The raid configuration is really up to you based on what your requirements are and the trade-offs you can live with related to performance and redundancy.
It's hard to give you a recommendation about where to put it on the 2 volumes you list because we don't have any information about your data activity or volume. All we can really tell you based on the info you gave us is to put it on the volume that's not going to fill up with the added storage required by your backups.