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Raid Question

By Larman
Oct 6, 2005
  1. Hi all, I wasn't sure where to put this topic so I put it under here.

    What I'm trying to find out is there really a "big" performance difference with Raid 0 (striping) verses Raid 1 (mirroring)? I have two 250GB HDs and I'm trying to weigh the pros and cons of which way to go.

    I appreciate any feedback.

    Regards
    Larman :bounce:
     
  2. vnf4ultra

    vnf4ultra TechSpot Paladin Posts: 1,388

    Hello, welcome to Techspot!

    Raid 0 will increase the hard drive speed overall, and give you the equivalent capacity of both drives (500gb). The con of raid 0 is that if one drive goes bad, neither will work, as they are made to be one logical unit. So it doubles the rate of failure compared to having one drive(you have two drives that could fail in raid 0 vs 1 drive if you just have one drive).

    Raid 1 will give you the storage of 1 drive(250gb), and each drive will be a copy of the other drive. It is no faster than a single drive, but it gives you a backup hd if one goes bad.
     
  3. Larman

    Larman TS Rookie Topic Starter

    Thanks for the input! Any idea how much faster having Raid 0 makes a system opposed to if it was one drive or "mirrored" acting as one drive?
     
  4. jobeard

    jobeard TS Ambassador Posts: 9,351   +622

    A good implementation of Raid-1 can setup a read from both drives and thus avoid the lost time awaiting one arm's seek delay (ie: start both at the same time). So Raid-1 gives parallel reads and serialized writes

    Raid-0 has the same opportunity to start ALL the arms seeking (eg: a raid-0 > 2 drives) and then transfer the data for both read and write. The performance boost will be proportional to the number of HDs attached (the more the better).

    Typical timings for 1 hd
    (seek + latency + transfer)*number of I/O requests

    Raid-0
    (seek*I/O requests)/num of HDs + (latency + transfer)*num of I/O requests

    this factors into
    seek*i/o requests vs (seek*i/o requests)/num HDs
     
  5. pkroks

    pkroks TS Rookie Posts: 259

    i have a raid 0 striping setup and would like to get rid of it... is there any way i can do this without losing the data please help. also a guide to getting rid of it would be great... ;)
     
  6. Larman

    Larman TS Rookie Topic Starter

    Thanks for the info. I'm not sure what makes one raid 0 good and one not but my configuration is two 250GB HDs.
     
  7. jobeard

    jobeard TS Ambassador Posts: 9,351   +622

    use hardware raid

    btw: if you're going to a RAID configuration, don't waste your time with a software only implementation. You're going to soak up extra CPU and there is a cost (ie delay) to all those cycles. By all means, get an hardware I/O controller which implements the RAID services. Do your homework as this stuff gets expensive.
     
  8. jobeard

    jobeard TS Ambassador Posts: 9,351   +622

    The safe and most likely to succeed would (imo) be to:
    capture the data files to a DVD or external USB 2.0 HD
    then reset/remove the raid configuration,
    reformat the HD
    reinstall the OS
    reinstall the applications
    and (whew!) copy back your data.
    If you're bold you might take some short cuts but make sure you get a copy
    of the registry
     
  9. pkroks

    pkroks TS Rookie Posts: 259

    how would i reset or remove the raid configuration? I use nvraid manager, but i cant select delete in the options. when i startup my computer there is an option to enter the raid configuration setup. if i do this i can delete the raid striping setup but it wont let me exit the config area unless i create a new raid setup (mirroring/striping/both etc)... how do i go about doing it?

    *Edit: I have tried to delete the partition from the config setup area before but i then created a mirroring item. on boot up it said there was a problem wiht booting so i went back, deleted the mirroring config and put striping back on... luckily enough my work and o.s and all was still there (as i thought that i had done something to screw up the computer)... :suspiciou
     
  10. jobeard

    jobeard TS Ambassador Posts: 9,351   +622

    you should DL the manual
    and see pg 5 to disable via the BIOS
     
  11. pkroks

    pkroks TS Rookie Posts: 259

    thanks will check it out! :grinthumb
     
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