benefits of raid.

[Jesta]

When I build my new computer I am thinking that i should go with a raid set-up. But other then what i was able to google i dont know much about what the actual benefits of a raid set-up are over a normal set-up.

Also are they hard to set up for a first timer like myself?


My plan was to get a raptor 10k rpm HD, then a larger 7200rpm seagate for storage.

Will the different speeds be compatible in a raid setting?

[screwballl]

It all depends on what you are wanting to get out of it. Safety suggests RAID1, storage says RAID0.

You need to know which raid setup you will be using. Also to setup RAID, both drives will need to be the exact same size, it usually helps to have both from the same manufacturer.

• RAID 0 "Striped" = use 2 drives together to get one large partition the size of both drives together (if both are 320GB drives, you will see one 640GB partition). Down side is if one dies, the info on both are toast. Provides improved performance and additional storage but no fault tolerance. Any disk failure destroys the array, which becomes more likely with more disks in the array. A single disk failure destroys the entire array and all data because when data is written to a RAID 0 drive, the data is broken into fragments.

• RAID 1 "Mirrored" = use 2 drives together to get one 320GB partition but it is mirrored onto the second drive so all read and write sequences are done from both drives. Provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning.

• RAID 3&4 - not suggested or hardly used nowadays

• RAID 5 "Striped set with distributed parity" - this requires 4 hard drives. This is like RAID 1 but spanned across 3 or more drives instead of only 2. If one drive dies, the rest work fine since the info is duplicated across all but one of the drives. You may lose some individual files but a majority of the data is still safe. This works by spanning the data across 3 of the 4 drives but in a staggered method so that if one dies, there will be only minimal data loss ince some is backed up on another drive.

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Then there are what is called "nested" levels.

• RAID 0+1: striped sets in a mirrored set (minimum 4 disks; even number of disks) provides fault tolerance and improved performance but increases complexity. The key difference from RAID 1+0 is that RAID 0+1 creates a second striped set to mirror a primary striped set. The array continues to operate with one or more drives failed in the same mirror set, but if two or more drives fail on different sides of the mirroring, the data on the RAID system is lost.

• RAID 1+0: mirrored sets in a striped set (minimum 4 disks; even number of disks) provides fault tolerance and improved performance but increases complexity. The key difference from RAID 0+1 is that RAID 1+0 creates a striped set from a series of mirrored drives. In a failed disk situation RAID 1+0 performs better because all the remaining disks continue to be used. The array can sustain multiple drive losses as long as no two drives lost comprise a single pair of one mirror.

So with these, the data is placed on 2 drives as RAID0 and on one of the other 2 drives as RAID1 so your data is actually on all 4 drives but written in 3 places (since RAID0 is seen as 1 place that spans 2 drives).
0+1 - jpeg file is split into 2 pieces, part of it on drive1, part on drive2 but it is also copied to drive 3 as a single piece which in turn is also copied to drive4 which is copying drive 3 at all times.
1+0 - jpeg file is written as one piece onto drive 3, then copied onto 4 and then drive 1&2 pick this up and split it into 2 pieces spanned across both drives.
0+1 = drive1+2 are read/written to first, then drive 3. then 4
1+0 = drive3 is read/written then 4, then split on 1+2

Hope this breaks it down for you.

If all else fails, just use the 2 drives like normal without the worry of RAID

[Hitman]

I wrote this quite some time ago, but it still has some good info in it.

RAID Guide

The current setup you are talking about will not benefit from a RAID setup. To break it down Barny Style, with RAID your goal should be one of 3 things. Increased Performance, Redundancy and/or combined storage. In your current setup you will only get combined storage, and you will loose the performance of your 10k rpm drive.

[Jesta]

Thank you for the help.

It would seem RAID isnt anything that would benefit me enough to change my set-up.

Increased performance is always nice, but i dont think its needed for what i do.

[polobunny]

Might I add that if you use a RAID0 setup for your system drive it can be a pain to backup? I did the silly thing of RAID0'ing 2x 320GB and filling them with crap. Now I want to re-install my OS and all, meaning I need to get my data out of there.
So I've had to buy a 1TB hard drive. :P
It's fun to do a RAID0 once in a while, if only for benchmark scores. In reality though, the performance difference in applications I use (games, photoshop, stuff like that) is minimal.