Balanced view on RAID 5?

For some reason people seem very opinionated about raid 5 and I'm trying to figure out why (largely negative). I know the write speed is going to be slower on raid 5, but I want to build a hassle-free system that I don't have to backup. I'm trying to limit my budget on a PC to about $11xx and really thinking of 3 500GB drives. I've read that the read speed is good, but is the write speed really as horrible as people make it out to be? In one thread I read that if the data file is larger than a single stripe it writes quickly because it doesn't have to do any calculations, in others I've just read it's slow all around.

I'm pretty much just asking if using 3 drives in raid 5 is suitable for torrents/gaming/school work. I don't do any video/photo editing or graphics stuff. Also suggestions on stripe size? I've never set up a raid before.

No. Any kind of RAID requires more regular backing up than a single drive system. RAID introduces driver issues, not to mention that if you hose your OS and have to transfer files from your disks to another PC you cannot do that. RAID is not a form of backup, and RAID is far from hassle free.
In terms of speed alone RAID 5 will be slow if you run it on an onboard controller. The only performance gains to be had are found in RAID 0, and in expensive enterprise class multidisk arrays.
I'm not saying that RAID is bad, its just not a backup. RAID is great for servers and workstations that have niche needs.

As for my personal view on the subject, RAID 5 has no business in a desktop PC. With the money you have in your budget you would do well to buy an external backup device and make regular backups of anything you want to keep, or just get 2 internal HDDs and look for some automatic backup software like this

http://www.newegg.com/Product/Prod [...] 6832150015

This device would be another cool idea,
http://www.newegg.com/Product/Prod [...] 6822136084

I agree with the comments above but if you do decide to RAID your drives the controller makes a huge difference. A dedicated card is the best option but if you use your motherboards controller keep in mind that Intel's Matrix Storage is significantly faster with less CPU overhead than Nvidia motherboards.

I see a lot recommendations of RAID 1 rather than RAID 5.

That works only in the smallest RAID systems. In a large RAID system, the economies of scale in RAID 5 far outstrips RAID 1 or RAID 0+1/1+0.

For e.g. (in this following illustration I say "raid 1" as a short hand for "raid 1+0" or "raid 0+1" variants, doesn't really matter for this example's purpose):

6 drives; 1 TB each. Using RAID 1. I get 3 TB.

Same 6 drives, using RAID 5 I get (approx) 5TBs.

Go to 8 drives: RAID 1 -> 4TB; RAID 5 -> 7TB.

I used 1TB as illustration, you can use 500GB to do the math and RAID 5 still shows the economies of scale quickly.

You can't achieve the same capacity with RAID 1 variants and still be within budget!

In the 8 drive example, if my target is 7TB of storage, I need 14 drives to achieve that! 7 drives more than RAID 5! Now you've also added 7 additional points of failure, 7 additional components of complexity, ** AND 7 ADDITIONAL HDD TO HAVE BUS CONTENTION over the controller (which could potentially end up slower than 8-drive RAID5!) ** Plus, good luck buying a RAID controller with 14 ports vs a raid 5 controller with 8 ports (a lot more common).

Additionally, if I'm going to spend all the money that RAID 1 solutions needed (to go to 7TB) anyway; there are TONs of ways to increase reliability of my basic 8-disk RAID and still cost less than 14 drive RAID 1 variants:

- buy 2 RAID controllers! Guard against controller failure.
- Install an online hot spare.
- install a UPS
- Even going to RAID 6 would cost less than RAID 1/14 drive!

So unless you're talking about small scale RAIDs (3 or 4 drives), you can't implement the same things RAID 5's can do with RAID 1 variants, without cost (or sometimes even performance) going out of whack.

Now... if your argument is that why would a home PC need 8 drives RAID. Think about expansion. When you first buy the home PC, perhaps 4 drive RAID is ok, when you need space 2/3 years later? It's not hard to see things doubling to 8 disks.