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I have a computer for general home use and mild gaming (not upgraded the graphics card so still on AGPx8). It is currently configured for striped access over two 80GB disks. Is this the best option? Should I consider upgrading the size of the drives and moving to a mirrored setup or is this only really important if there is no other backup solution available? What are the driving factors behind available RAID configurations for the average home user?

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RAID is never a backup solution –  Dan McClain Jul 19 '09 at 20:33
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What? Why? phsr? –  bobobobo Aug 8 '09 at 15:52
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7 Answers 7

up vote 11 down vote accepted

Depends on what you are striving for:

Raw speed: RAID0

Mirroring: RAID1

Integrity + Speed: RAID5 (one disk parity)

Notes on each:
RAID0: If you lose one drive, you lose all data
RAID1: You have to cut your total drive size in half
RAID5: You lose one drive's worth of space, and need at least 3 drives. You will need to wait for the drive to rebuild if you replace a bad drive, and during a rebuild, if you lose a second drive, you will lose your data

You can also combine RAID configs to achieve different setups (RAID10, RAID50)

All being said, if you are looking for speed, but don't care about losing data, go RAID0, if you are looking to have a backup drive incase one goes down, go RAID1. RAID5 is good if you want some speed, and to have a backup incase on drive goes.

One thing to remember: RAID is never a backup solution

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Note that RAID5 with n drives should be roughly as fast for READING as RAID1 with n-1 drives. However, RAID5 will be slower for writing due to the parity calculations necessary. –  ChrisInEdmonton Jul 25 '09 at 18:16
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+1 for RAID is never a backup solution. –  Keck Aug 5 '09 at 13:59
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Guys. Why do you keep saying "RAID is never a backup solution" –  bobobobo Aug 8 '09 at 15:53
    
Raid is never a backup solution because you can still lose your data if something "catastrophic" happens (your RAID adapter goes, or lightning strikes and fries half of your harddisks, rendering the array uncoverable –  Dan McClain Aug 20 '09 at 1:18
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@phsr correct me if I'm wrong, but RAID1 is can be considered a 'backup solution' only in the sense that it provides redundancy if one of the drives physically fails (which is more common than anyone would like to have to deal with...) –  Josh Newman Sep 23 '10 at 22:48
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I'd recommend using something with mirroring — probably RAID 1, because I don't feel like there's a great need to get fancy with a home system. Backups are one thing; degraded but uninterrupted service when one of your disks blows up is another, very worthwhile thing.

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For home use all I need is a mirror, RAID1, two drives, nothing else, so many motherboards support this now. My strategy is that I have a third identical drive that I backup to, so in case the mirror fails I get a new backup drive and use the old backup drive to fix the mirror. I'd rather use 3 drives for this than RAID5, and a stripe is only good if you don't care about the data on it. Oh, and the backup drive is only powered on during backups, so it should have a longer life than the other two that are on all the time. –  Bratch Aug 5 '09 at 14:17
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RAID 0 (striping) is almost never appropriate.

The statement that it "improves speed" is misleading: it improves the maximum transfer rate, but that is irrelevant in most applications (the only exception for a home user that I can think of would be video editing) as modern HDs have bulk transfer rates upwards of 70 MB/s which are more than sufficient.

What makes HDs slow is usually random seeks, and RAID 0 does absolutely nothing to improve those. RAID 1 potentially does (probably not with software RAID though), so in fact RAID 1 may speed up typical applications far more than RAID 0 - and it drastically reduces (rather than drastically increasing) your risk of total data loss.

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Raid is NOT a backup solution. It's a redundancy solution (or a performance enhancement solution if you're using it for striping). A large number of disk failures are due to environmental factors (excessive heat, etc) so assuming you can use it instead of decent back ups is not a safe bet.

If you have a RAID setup looking for a performance boost go with RAID 0 for striping. If you're doing it for backups, drop RAID and find a good online backup service.

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With striped you get faster access and all you space. With Mirror you get data redundancy and half your space. What is more appropriate depends on your needs.

If you want to read more detail info, go here to wikipedia.

From there: "RAID 0 (striped disks) distributes data across several disks in a way that gives improved speed at any given instant. If one disk fails, however, all of the data on the array will be lost, as there is neither parity nor mirroring."

"RAID 1 mirrors the contents of the disks, making a form of 1:1 ratio realtime backup. The contents of each disk in the array are identical to that of every other disk in the array."

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Before you decide on which configuration to use, you need to look at the application. Typically with a home PC, the hard drive is asked to read data more often than writing data. For example with a game, you only ever install it once which is a writing operation, but when you play the game, you constantly load levels, reading.

What most people miss with looking at RAID configurations is that RAID0 gives you a 2x reading performance as well as data security, the same reading performance that RAID1 achieves. RAID0 is only inferior to RAID1 in writing operations and storage capacity.

Since most of the time your computer is doing reading operations, i personally would go with RAID0 for it's data security and sacrifice the writing performance of RAID1 as it is not used as much.

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Yeah but, save game can take a couple of .. seconds for games like NWN –  bobobobo Aug 8 '09 at 15:56
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For the average home user, RAID should not even be a consideration.

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RAID 1 sounds reasonable. I'm willing to spend $100 for a second drive to automatically mirror my data. –  bobobobo Aug 8 '09 at 15:55
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