ide raid

say you build a system with two harddrives in RAID-0. Is there any MORE chance that the drives will fail or that data will be lost than if i had two harddrives in RAID-1? I know about speed, just wanted to know about safety.

<P ID="edit"><FONT SIZE=-1><EM>Edited by backflash001 on 08/27/02 06:01 PM.</EM></FONT></P>
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  1. The whole idea with raid1 is that you have two hard disks that are exactly the same. If one takes a massive sh*t on you, your system just keeps right on running.

    Raid0 is different. Yes, there's an increased risk, if you look at the pure statistics and do the math.

    I still have a 6.4gig ibm and 5.7gig maxtor drive. Both work perfectly. If your aren't running raid1 right this second, raid0 isn't going to save you from anything. So, if you're not worried about losing a hard disk right this second, raid0 isn't going to make you lose any sleep. You're not sweating it with one drive, and the chance of a hard disk failure nowadays is like winning the lottery.

    The way I look at it is like this: if any hard disk is going to fail, it usually does it within about a year. The majority of people lost at least one 75gxp within the first year, but there were some exceptions. Mine lasted something like 14 months.

    Hook up your raid0, and be vigilant about backing up stuff you don't want to lose. With a cd burner, it would take you about 15 minutes each weekend to find all your outlook/favorites/documents and compress them down and burn to disk, if you keep track of where you save stuff.

    C@lling it like I c it...
  2. Quote:
    and the chance of a hard disk failure nowadays is like winning the lottery.

    Unless you are using IBMs deathstar. In that case, the chance of a failure is like NOT winning the the lottery :-)
  3. I dont understand why so many people say that RAID-0 is insecure. The way i see it, the chance of each harddrive crashing remains about the same. I have had my harddrive for over 3 years and i never had any trouble with it. Same as all of my other harddrives. So i really dont see why RAID-0 is any less secure. Unless the raid controller loses data or something like that, but i dont know if that happens.
  4. Quote:
    The way i see it, the chance of each harddrive crashing remains about the same...So i really dont see why RAID-0 is any less secure. Unless the raid controller loses data or something like that, but i dont know if that happens.

    i am a newbie, but this is how i see it:

    we are assuming that each hard drive has the same chance of failing...if this is true, and you use RAID 0, if *either* drive fails, then you loose all...however, if you are using RAID 1, since *everything* is backed up, if *either* drive fails, you still have a backup of your entire system. sooo, you have twice as many chances (assuming you use 2 hd's...if you have 3 hd's, you have 3x more chance of loosing all...etc) of loosing your data using RAID 0 as using RAID 1

    BUT...as was stated earlier, RAID 0 is not any more chancy than not using RAID at all, but if you are just comparing RAID 1 vs RAID 0, i do believe that explains why RAID 0 is less secure...

    i *personally* would use raid 0, cuz its a waste of my disk space to back everything up...i have faith in my WD hd's ;)

    however...being a newbie, please please please correct me if i'm wrong :)
  5. Quote:
    Unless you are using IBMs deathstar. In that case, the chance of a failure is like NOT winning the the lottery

    I have used ~10 of them, and none of them failed although I didn't have 75GXP. My current ones are 1 of 120GXP and 3 of 60GXPs (2 has been setup to run as RAID-0 for more than 6 months now).

    :smile: Good or Bad have no meaning at all, depends on what your point of view is.
  6. if you are concern with speed and security, why not using raid 0+1? but at least 4 hdds to complete raid 0+1....
  7. Just to make sure I am assuming correctly, since I didn't see it stated clearly, but when you go with Raid 1 with say, two hdds, you are only using the capacity from one, right? Since the second is being used to mirror?
  8. Quote:
    ...when you go with Raid 1 with say, two hdds, you are only using the capacity from one, right?


    yeah,
    the only thing that RAID 1 does is mirror the data from one drive to the other. So instead of data being written to only one drive, the same data is written to two. Therefore, you only use the capacity of one drive (considering you have two drives of the same size) or the capacity of your smallest drive (if both drives are of diffrent sizes).
  9. Quote:
    sooo, you have twice as many chances (assuming you use 2 hd's...if you have 3 hd's, you have 3x more chance of loosing all...etc)

    Your math is wrong. A quick example proves this. Suppose you have two drives each with a probability of failure equal to 0.5. According to you calculation the probability of failure of a RAID0 array would be 1, which is clearly wrong. The correct probability is 3/4 and is obtained by:

    PR0=1-(1-P1)(1-P2)...(1-PN)

    where PR0 is the probability of failure of the RAID0 array and P1..PN is the probability of failure of the individual drives. For small probabilities it just happens to approximate N*Px

    The probability of failure of a RAID1 array is:

    PR1=P1*P2...PN

    and hence the ratio of failure probability of RAID0 to RAID1 is:

    PR01=(1-(1-P1)(1-P2)...(1-PN)) / (P1*P2...PN)

    Which is larger much than N. So comparing RAID0 to RAID1 you are MUCH worse off regarding data safety.

    A quick example: Suppose you have two drives each with a probability of failure of 1/10, then:

    PR0=0.19 (approx 2*0.1)
    PR1=0.01

    But PR01=19. Meaning the probability of data loss is 19 times larger with RAID0 compared to RAID1. For smaller probabilities, this ratio becomes even larger. E.g. for a failure probaility of the individual drives of 1/1000, the ratio is 1999. The ratio approximates N/Px<P ID="edit"><FONT SIZE=-1><EM>Edited by HammerBot on 08/29/02 05:45 PM.</EM></FONT></P>
  10. Quote:
    3 of 60GXPs (2 has been setup to run as RAID-0 for more than 6 months now)

    Ouch. I reaally hope for you that you take backup of your irreplaceable data often. The Deathstar syndrome is not just a rumor. Its a fact. A LOT of people have lost a lot of data due to the 60GXP (I lost one about 2 months ago, and it was just 4 months old). Considering you have two of them in RAID0 you have approximately twice the probability of data loss.
  11. crap...i knew i should have paid more attention in prob & stats...heh :) thanx thou
  12. While I'm here, I have one more question. I'm thinking about moving to IDE RAID myself. Can I set up my array with three HDDs and add in a fourth later on easily? Or will it take another complete reformating and resyncing of all the drives? I wonder if I should wait until I can get the exact configuration I want before doing anything ^_^;
  13. Quote:
    Can I set up my array with three HDDs and add in a fourth later on easily?

    I assume you mean RAID0. In that case, No. Any change in the array (stripe size, number of disks) requires reformatting of the array. And further I even dont think that a RAID0 array works with 3 disks. I think it has to be an even number. But im not sure about this.
  14. how about, if currently I'm using both maxtor 20gb hdds on the first channel of my Highpoint Tech 370 onboard raid controller, 1 as master and 1 as slave. Both are striped in Raid 0 mode. Can i just move my slave drive to the second channel's master without breaking my stripe? Thankx

    The No. 1 cause of divorce is marriage - 100% of all divorces starts with marriage
  15. Quote:
    Ouch. I reaally hope for you that you take backup of your irreplaceable data often.

    Yep, have my data on a RAID 0+1 array with overnight tape backups which I transfer onto my machine at home. So short of someone dropping a nuke on my town I feel my data is pretty safe.
  16. Quote:
    Yep, have my data on a RAID 0+1 array with overnight tape backups which I transfer onto my machine at home. So short of someone dropping a nuke on my town I feel my data is pretty safe.

    Cool. Its like insurance. You hope you'll never need it. But when the accident happens you'll be happy you have it.
  17. Quote:
    Can i just move my slave drive to the second channel's master without breaking my stripe? Thankx

    Yes, that should be possible. Perhaps you'll need to enter the setup of the RAID controller and specify the new position of the drive. But the format of the data on the drives in master/slave configuration is no different from that in master/master configuration, so it should be possible.
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