I know it's probably a simple question, but I've had one hell of a bout of food poisoning tonight and I just can't get it through my head.  I passed out during it and I'm still light headed.  But I have to get this hard drive going by in the morning.

I basically need to know my best option for speed and reliability.

I have 2 identical WD Caviar 320 GB hard drives.  (One is brand new and has a 16mb buffer and the other is about 1.5 years old and has an 8mb buffer, but identical other than that).

I also have an old IDE 40 GB WD drive that I've kept around for backup.

I'm running out of room on the 40 GB drive so I would like to use the 8mb buffer 320 GB drive as a backup.  So then I started thinking about setting them up in a RAID1 for constant backup.  

I don't fully understand it though.  Will it have a negative impact on speed?  Also, my mobo says it can handle RAID 0, 1, 0+1, & 5.  What is 0+1 & 5?  They just don't make any sense to me and I can't figure out if I could use either.

Thanks for your help.

afaik, for Raid 0, 1 0+1 - the drives have to be identical, buffer included.

look here:
http://en.wikipedia.org/wiki/RAID

eta: The stuff on the wiki is complicated

Raid 0 - Gives you 2x the drive performance. If one drive breaks you lose all your data.
Raid 1 - Both disks are mirror images of each other. If one physically breaks you have a perfect duplicate to replace it.
Raid 0+1 - 2x Drive performance, with a backup drive for each of the first two (needs 4 identical hard drives total)

hope that clears it up a tad

RAID  IS NOT A BACKUP SOLUTION!!!!!!!!!!



RAID provides FAULT TOLERANCE.   If you have a RAID 1 to 'back up'  your stuff, and you, say, delete a file... it's gone on ALL of the drives.  Get a virus, it's on ALL of the drives.  


RAID IS NOT A BACKUP!!!!!!!!!!

If you want to do RAID-1 you will need 2 identical hard drives, or it will limit the bigger one to the smaller size... Im not 100% sure if the different buffer sizes will make a difference or not.

I have 2 500's in a raid-1 array for redundancy (against physical hard drive failure).

As far as speed goes, no noticeable difference in read speed, although you likely wont get anything noticeable without a RAID card and probably 4+ drives...


IIRC raid 5 (you need at LEAST 3 drives) splits the disk into the same number of "segments" depending on how many hard drives you have. Each segment has portions for each other hard drive as a backup. If you have a hard drive failure, instead of coping from 1 drive to another, it copies from ALL the drives to rebuild the new "array" much quicker. It will usually read quicker (having multiple storage drives) and write quicker (since it splits the info up on multiple drives)


Raid 0+1 (or 1+0) needs min. 4 hard drives. Essentially you take 2 sets of hard drives, and "stripe" them (so 2 hard drives acting as 1. More space) and then 2 take the 2 SETS of hard drives, and you MIRROR them for redundancy, or backup.


For basic "backup" and storage, raid 1 is the best option, although I doubt you'll see or notice any increase in read speed or load time on things.

ETA

as MattQ said, if you delete a file, or have a virus problem, it wont act as a "backup" at all. It safeguards you from PHYSICAL damage! If you want a backup hard drive, any brand of external hard drive will usually have backup software to backup files as you create them. Im sure you can get programs to do this with an internal hard drive as well (possibly even Microsoft has stuff like that).

Good call.  Thanks.

I told you my head wasn't clear.  

I have a couple of 16GB USB drives to backup important stuff, so not all would have been lost.  I'll just proceed with how I planned to have it and keep using SyncToy on a weekly basis.

Anything other than that is just asking for trouble.

Basically RAID is either speed or reliability unless you have four or more HDD's.  With four you can double the speed and become tolerant of one HDD failure (reliability).

With only two drives, you get speed or reliability but not both.  If it were me and I had only two drives, without hesitation I'd go for reliability.  Oh wait, that's what I already did.  :-)

Of course, I chose that option only AFTER I had a RAID 0 set up fail on me.  :-(    RAID 0 increases speed but cuts reliability in half due to the use of two HDD's, either one of which can fail and take out the entire array.   The HDD is the lowest reliability item in your PC, so cutting its reliability in half is bad ju-ju.

Yes, tape [LTO] FTW !



I used HDDs for backup/archive.Write data and store them to shelf.Verry bad surprise comes after few years when I try to extract some files  - almost half of the brand new HDDs,used once ,failed.Now I believe only in tape.





 

Actually one thing I'd recommend for backups nowadays is an online solution.  This gives you something offsite   - if your house burns to a pile of ashes, all of your pictures and critical files can still be gotten to.

I use Jungle Disk myself.   Right less than $5/mo for my backups, and that's with about 6-7GB of photos and my 12GB music collection.    It's all encrypted, so even if 'they' wanted to look at my files, they wouldn't be able to see what I have in there.

First off, get some sleep and take care of this later.

Second, you don't need to RAID anything in a normal desktop - especially not if "backup" is your key.

Third, RAID 5 and the third drive make hot swappable.