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I'm building a new computer over the summer. I'm fairly competent in computer hardware, and am thus building the computer from scratch. I have everything planned out, but I was wondering if I should consider RAID, and if so, which RAID to use. I plan to purchase 2x1TB drives. Currently I'm leaning toward RAID 1 for the redundancy -- I've heard newer super-capacity drives fail more often than one would think, and I don't want to have a problem and lose all my data. What do you think? My mobo supports RAID 0/1/5/10. Is it worth it to use RAID at all, or should I just use a backup service like Mozy? Should I consider RAID 0 instead, for the performance? I'm kind-of going back and forth on this one. Thanks a lot for your help.

EDIT: I'd like to avoid the OS drive different from Data drive situation, because that can get frustrating when programs like to store a lot of data in their program files folder. I've lived with that situation before and it gets annoying after a while.

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Newer large drives do not fail more often than others, you just lose more data when they do die with no backup. –  Troggy Jul 23 '09 at 17:27
    
From your question, it already appears that you have a good understanding of basic raid, so i've got nothing to add there. That said, i do have some anecdotal information. I wanted performance and reliability. So i chose a pair of enterprise grade drives (Western Digital Raptors) that were fast (10k RPM) and ran them in raid 0. I ALWAYS made sure i had copious amounts of cooling on these drives and have NEVER had a problem with them. This was almost 5 years ago and i'm still using them today. –  NoCarrier Jul 23 '09 at 17:28
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Sorry to bust your bubble, but the WD Raptors are not enterprise grade hardware. They're damn fast drives though. –  Paul McMillan Jul 23 '09 at 21:16
    
Can you describe the problems you've had with programs installing data into the "Program Files" folder? Is it to do with games? –  sblair Jul 26 '09 at 1:50
    
Mostly games, yes. But I think ~300GB should be enough. I'm thinking about going with a 300GB 10K rpm drive for program files and one 1TB drive for data. –  NickAldwin Jul 26 '09 at 3:26
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10 Answers

up vote 11 down vote accepted

If data loss is your concern, please remember that RAID is not backup. I suggest you invest in some form of backup, whether it's a 'cloud' solution or a simple rsync job to another computer.

This way, you can have your RAID 0 for performance as well.

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Cloud solution is not viable for anyone with real amounts of data. –  Paul McMillan Jul 23 '09 at 21:16
    
Partly agree, and that's why I suggested an external backup. –  Robert Munteanu Jul 23 '09 at 22:36
    
True that RAID 1 is not a backup, but, on the other hand, RAID 0 actually doubles your chance of losing the data on your drive. –  TM. Jul 24 '09 at 19:48
    
It's much more than that - see en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0_failure_rate –  Robert Munteanu Jul 24 '09 at 20:24
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Be aware that even if you are mirroring drives, the raid controller itself is a single point of failure.

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Upvoting so that next time, you can post something like this as a comment. –  marcusw Mar 21 '10 at 0:23
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It may be worth considering using an SSD as the OS/applications drive, for excellent performance (see Anandtech for a review of the latest Intel X25-M drive).

I opted for this, with two non-RAID HDDs for data (plus an external drive for backup), which works well.

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On the desktop RAID allows you to keep working through a hard drive failure and fix it at your convenience. And perhaps saving some work since the last backup.

However, in my experience, if you have proper backups, RAID for workstations just isn't worth the bother. The rebuilds are often not trouble free and the rest of the PC is a bunch of single points of failure, many of which can trash the disk anyway - memory, power, motherboard.

The RAID controller is a single point of failure. If it goes you have to be able to replace it with the same or compatible controller or you lose the array anyway. If it's a motherboard controller are you going to be able to get a compatible replacement in 2 years time? Assuming it didn't take the array with in when it failed.

RAID isn't a backup strategy - there's no substitute for real backups. Something like, say, at least 3 external drives and backup software that gets everything and can do a bare metal restore is where you should start. You didn't say what OS you have, but there are good options for Windows Linux and Mac. And if you do it right the recovery is quick and sure.

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I generally buy two fast drives (10K RPM) that are relatively small and run them in RAID 0 (stripe) for my OS partition and two large drives (7200 RMP) in a RAID 1 (mirror) for my data partition. That way, if I lose a drive in the striped array, I just rebuild my OS and my data is protected by the mirror. Of course, that requires 4 drives, where you could do a RAID 5 with 3 drives, but in my mind, it's the easiest.

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Do not bother. unless you're going to spend a pretty penny on a nice RAID card YOU WILL REGRET IT!!!!!!!!!!!!!!!! raid systems built into consumer motherboards are shotty at best and completely unsupported.

RAIDS are only good for drives that die. file corruptions and the like are not prevented with a raid.

With the average lifespan of a hard drive being about 7 years you're better off just getting an SSD for your OS and page file and just a couple TB drives for data.

if you're insistent on doing a RAID I would do a RAID 5 using 3 drives and a 4th as a spare.(or if you get a good raid card 4 drives in the raid and a 5th for spare) it's a good combination of speed and reliability.

ALSO: keep in mind you should NEVER EVER for sake of performance keep your page file on a RAID of any kind (except a mirror where ALL drives are identical in every way). An operating system is constantly writing and reading the page file and all the added math and overhead it takes to write it to a RAID will degrade your performance.

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If you're between raid 0 and 1, check out 10. It's redundant (you'll halve your usable space), but you also get the reading performance gains of raid 0.

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Use a small drive as your system drive, and then mount your larger drive within your smaller drive under a folder. Then it looks to your programs as if they're storing data on the C drive, while it's actually getting stuck on your big cheap media drive.

Windows XP and above have this capability.

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Sounds like an excellent solution, thanks! –  NickAldwin Jul 24 '09 at 4:19
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Only use RAID if you have a network computer, or NAS, or external drive that can store automated image backups of your system partition. That way when your RAID volume craps out (which it will) you can just restore from the last image backup.

As for RAID 1 (mirror) vs 0 (stripe): It's basically a matter of performance vs downtime during drive failure.

RAID 1 will sacrifice the 2x write performance, but gain you the ability to just pop another drive in when one drive fails without any downtime.

RAID 0 will give you 2x write performance (which is nice), but if a drive fails you will be down until you can pop another drive in and restore from an image backup.

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It is very rare to actually get a 2x performance increase with RAID0 –  Zoredache Mar 21 '10 at 2:52
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Don't do anything other than RAID-1 at home unless your data is backed up. Been there, done that. RAID-1 is great because you can take any of two disks (or more than two if you are feeling paranoid) and use it as regular non-RAID disk to get your data. So if your controller fails - no big deal. RAID-1 can also increase your read performance since data can be read in stripes from two drives just like in RAID-0

Tried RAID-5 to get both speed, space and redundancy... Well because of faulty controller two out of four drives went offline in my array and it fell apart. It was extremely hard to put it back together. I managed to salvage my documents and photos but the operating system was gone.

Here's what I have setup right now: Desktop PC is backed up daily to WHS (Windows Home Server), photos folder is manually replicated to redundant share on the same WHS (in theory it should survive failure of I HDD on WHS), all shares from WHS are regularly backed up to an external HDD, and finally shares with sensitive data like photos are backed up to Amazon S3 via Jungle Disk.

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