3 drives of the same size is the minimum requirement for RAID 5, you would not or could not use any of the RAID 5 drives for anything else. Using 4 or 5 drives is where RAID 5 starts to shine. If you were using only 3 drives and one of the drives fails your server would still be functioning but there would be a big performance hit. If you were to use 4 or 5 drives and a drive failed it would not run much slower.
As for as backups go the best solution it to not have them on the same server. If a hacker got access to you server all your data on that server is at risk, including your back-ups. If you did want to use another drive for back-up purposes, it could not be part of the RAID 5 array. You would need a separate SCSI or IDE drive for that.
You could just make a RAID Level 0 array out of 2 of the drives and use the 3rd for a back-up drive, but you would loose a lot of space.
Last edited by sitekeeper; 08-27-2002 at 01:53 AM.