Page 1 of 4 1234 LastLast
Results 1 to 10 of 38

Thread: What is RAID?

  1. #1
    Sunshine Flavored Lollipops Zephik's Avatar
    Join Date
    Oct 2006
    Location
    Spokane, Washington
    Posts
    5,145

    Default What is RAID?

    I've tried Webopedia, Wikipedia and a few other websites that have attempted to explain what RAID is, but I just don't get it. What is RAID?? I hear all of this talk about Striping and Mirroring and it just goes through one ear and out the other. Could someone explain what RAID is and what these terms are in monkey talk? Just get me to understand what it is and what its used for, then if you want you can go ahead and get technical with it.

    Just for your information, I'm asking because the motherboard I am getting has RAID, which is something I've never had before. It has 0/1/0+1/5... whatever the heck that means. lol
    People are stupid; given proper motivation, almost anyone will believe almost anything. Because people are stupid, they will believe a lie because they want to believe it's true, or because they are afraid it might be true. People’s heads are full of knowledge, facts, and beliefs, and most of it is false, yet they think it all true. People are stupid; they can only rarely tell the difference between a lie and the truth, and yet they are confident they can, and so are all the easier to fool.

  2. #2
    Austral Alien
    Join Date
    Jan 2007
    Location
    Newcastle, NSW, Australia
    Posts
    2,194

    Default Re: What is RAID?

    RAID is using more than one HDD at once.
    It could be using two HDD and it writes and reads top both at once, sharing the data, effectively doubling your read/write speed.
    However, if one drive dies, you lose ALL your data.

    Or RAID can write the data to two dives at once, so if one drive dies, you still have an exact copy of that data on the other drive.

    From there, there is a combination of them. That is the basics though.
    Quote Originally Posted by Crimson Sky View Post
    hahaha..."Wacky"
    -Wackello Capello

  3. #3
    Austral Alien
    Join Date
    Jan 2007
    Location
    Newcastle, NSW, Australia
    Posts
    2,194

    Default Re: What is RAID?

    Here's a post I was looking for:

    Quote Originally Posted by Redundant View Post
    RAID 1 (redundancy) and RAID 0 (speed) use 2 drives

    RAID 10 and RAID 1+0 uses 4 drives

    Check out the different configurations.

    This post is perfect with my screen name.
    Quote Originally Posted by Crimson Sky View Post
    hahaha..."Wacky"
    -Wackello Capello

  4. #4
    Sunshine Flavored Lollipops Zephik's Avatar
    Join Date
    Oct 2006
    Location
    Spokane, Washington
    Posts
    5,145

    Default Re: What is RAID?

    Well, I only have one hard drive. So is RAID pretty much useless unless I have two or more hard drives?
    People are stupid; given proper motivation, almost anyone will believe almost anything. Because people are stupid, they will believe a lie because they want to believe it's true, or because they are afraid it might be true. People’s heads are full of knowledge, facts, and beliefs, and most of it is false, yet they think it all true. People are stupid; they can only rarely tell the difference between a lie and the truth, and yet they are confident they can, and so are all the easier to fool.

  5. #5
    Austral Alien
    Join Date
    Jan 2007
    Location
    Newcastle, NSW, Australia
    Posts
    2,194

    Default Re: What is RAID?

    That is correct. You need more than one drive.
    Quote Originally Posted by Crimson Sky View Post
    hahaha..."Wacky"
    -Wackello Capello

  6. #6
    Administrator OvRiDe's Avatar
    Join Date
    Dec 2005
    Location
    Tulsa, OK
    Posts
    4,586

    Default Re: What is RAID?

    The link Bucko gave is pretty good about telling the different types of RAID configurations. I have had alot of experience with RAID controllers and taken several courses from storage manufacturers. So I will try to shed a little light that helped me on the RAID concept itself.

    First RAID stands for Redundant Array of Independent Disks.

    RAID 1 is the most basic of raid. Everything written to one drive is also written to another drive, thus also called mirroring. Not much more to say about that.

    The rest really boils down to what we call Striping. What that means is a portion of the data is being written to multiple disks. Since everything stored on a hard drive is essentially bits (1's and 0's) it takes the bits and sequentially writes them to the multiple drives one after another, thus "striping" the data across X number of drives. This is known as RAID 0, there is no redundancy or recovery for this type of data. So if you loose 1 drive, the data is then incomplete and therefore unreadable.

    So know your saying .. thats not cool.. Sure it may be fast but it seems kind of risky! Your right. Thats when the next levels of RAID come in. Again the most basic is to mirror your RAID 0 stripe set. This is known as RAID 0+1 or some like to call it RAID 10. All that means is you Mirror your stripe set to an equal number of drives. ie. If you have a 3 drive RAID 0 stripe, it would mirror it to 3 other drives making a total of 6 drives.

    So.. you say I don't want to use that many drives and only be able to use half the capacity. Well thats where the "Stripe sets with parity" comes into play. Parity brings a way of recovering the data if one of the stripes is lost. How does it do that?? Its freaking MAGIC.. no not really.. Its actually quite simple. A parity bit allows you to recreate the data that is missing.

    For example lets say you have 3 drives. If Drive 1's corresponding bit is 0 and Drive 2's corresponding bit is 0 then Drive 3 (the parity drive, more on that later) would be 1.

    This is all basic binary arithmetic. Which dictates the following

    0+0=1
    0+1=0
    1+0=0
    1+1=1

    So with the information we have on all 3 drives we can alway rebuild a missing set of the stripe.

    Lets say we loose Drive 2. Since we know that Drive 1's bit was 0 and that the parity bit on Drive 3 is 1 we can deduce that:

    0+X=1 and we know that 0+0=1 so Drive 2's bit would have to be 0. So then when the drive is replaced, the RAID controller can rewrite the drive using the information from the other 2 drives. At this point it doesn't matter which drive is lost, you always have the information needed to rebuild it. Its not as fast as RAID 0 because you still have to read and write the parity bit, but its a lot safer, as long as you don't loose more then 1 drive at a time. Then you are back to not having enough information to rebuild the data.

    Once you have gotten to the "Stipe set with Parity" there are 2 basic flavors. You have RAID 3 and RAID 5. I won't go into to much detail there, because the link that Bucko and Redundant posted covers that. It basically boils down to RAID 3 uses a dedicated parity drive and RAID 5 spreads the parity bits evenly across the stripe set.

    I know this has been a bit of a long read but I hope it helps shed some light on the basics of RAID sets.

  7. #7
    Sunshine Flavored Lollipops Zephik's Avatar
    Join Date
    Oct 2006
    Location
    Spokane, Washington
    Posts
    5,145

    Default Re: What is RAID?

    Well thats lame.

    Way to drop the disappointment bomb on me there Bucko! geeze, haven't you ever heard of lying?

    LoL
    People are stupid; given proper motivation, almost anyone will believe almost anything. Because people are stupid, they will believe a lie because they want to believe it's true, or because they are afraid it might be true. People’s heads are full of knowledge, facts, and beliefs, and most of it is false, yet they think it all true. People are stupid; they can only rarely tell the difference between a lie and the truth, and yet they are confident they can, and so are all the easier to fool.

  8. #8
    Today is a good day to compute. The Black Pumpkin's Avatar
    Join Date
    Aug 2006
    Location
    Lake City, FL
    Posts
    247

    Default Re: What is RAID?

    It helped me, OvRiDe.

    That was a very good "short" guide!

    +rep

  9. #9
    Austral Alien
    Join Date
    Jan 2007
    Location
    Newcastle, NSW, Australia
    Posts
    2,194

    Default Re: What is RAID?

    Quote Originally Posted by SnowFire View Post
    geeze, haven't you ever heard of lying?

    Sorry.

    <lie>you can use one drive, but you have to overclock the HDD by raising the voltage to at least 450v. You also need to underclock the cooling fans and raise the FSB of every second USB port.</lie>
    Quote Originally Posted by Crimson Sky View Post
    hahaha..."Wacky"
    -Wackello Capello

  10. #10
    Sunshine Flavored Lollipops Zephik's Avatar
    Join Date
    Oct 2006
    Location
    Spokane, Washington
    Posts
    5,145

    Default Re: What is RAID?

    Thanks OvRiDe! That cleared so much up in my head, it all makes alot more sense now!

    ...dangit, now I want to go buy some more hard drives... lol
    People are stupid; given proper motivation, almost anyone will believe almost anything. Because people are stupid, they will believe a lie because they want to believe it's true, or because they are afraid it might be true. People’s heads are full of knowledge, facts, and beliefs, and most of it is false, yet they think it all true. People are stupid; they can only rarely tell the difference between a lie and the truth, and yet they are confident they can, and so are all the easier to fool.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •