Question on raid 1?

By ingeborgdot
Jul 15, 2007
  1. My mobod will support many different types of raid so that is not a problem. My question is about raid and the os. What would be the best way to do it. I don't want any other type of raid so don't go there. Any way should I put the os on a whole seperate drive and raid the the other two drives or should I partition the drive and do it that way? Any advice? Thanks.
  2. k.jacko

    k.jacko TS Rookie Posts: 493

    I don't see the point in partitioning, it won't do much to help.
    Raid 1 = mirroring, so i'd use the other 2 drives as you said and raid them together, assuming your onboard controller lets you do that.
    Bear in mind that you will then only have data redundancy and not system files.
    Someone might come along shortly and explain a better way to mirror just 2 drives together, although you may find its more straightforward than you first thought.
  3. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    I would partition so if or when I need to reinstall the os I don't have to mess with all the document, pic, videos etc. as they will be on a separate partition.
  4. AlbertLionheart

    AlbertLionheart TechSpot Chancellor Posts: 2,026

    With the wisdom of hindsight, data is precious; programs can be reinstalled. Install the OS and applications on a boot drive, RAID1 the other two to duplicate the data across the two drives - one fails you still have the other one.
    RAID0 is great for speed but if one drive fails you have lost all of it.
  5. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    creating a pair of partitions and THEN mirroring the pair is pointless and a
    worstcase performer too :(

    the point of a mirror is data being left on a usable DEVICE (not a failing one).
  6. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    Why is it pointless? You are getting a mirror of the os and of docs etc. You have a 50% less chance of failure.
  7. Justin

    Justin TS Rookie Posts: 942

    He means if you make 2 partitions on the same physical disk, and mirror those to each other

    Which would be pointless
  8. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    You're assuming that only one partition becomes inaccessible.
    What happens if the HD motor freezes, a head crashes on the recording platter,
    or the electrical components fail? You loose both partitions at the same time :(
  9. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    So you are saying both disks go bad. Well then I am screwed. If only one disk goes bad the other has the info and I just stick a new hd in and all the info is rewritten. It is a lot safer then only one drive.
  10. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    backup here:
    hd-1 for the OS
    hd-2+hd3 as a mirror​
    this is ok
    hd-1 for the os
    hd2 with two partitions mirrored​
    is no better than
    hd-1 for the os
    and hd-2 for the data​
  11. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    I just got done talking to a very respected tech person. He said that by using 2 hard drives and partition them into os + apps on one and docs, pics, and video etc on the other partition and then mirroring them is as safe & good as anything. He still recommends an external backup also to ensure there is less chance of failure. He recommends precautions such as good ups also.
  12. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    I think you misunderstood him as this would not work as literally written.

    edit: OOPS! I misread the intent. Yes, one hd with two partitions then mirroring that HD to another would be just fine!
  13. Justin

    Justin TS Rookie Posts: 942

    You're not understanding what we said earlier, which is that mirroring a partition to another partition on the same disk is stupid and pointless, which it is.

    Also, while I do encourage people to use mirroring, understand that RAID IS NOT A BACKUP SOLUTION. If you count on RAID to protect your data, you're using it incorrect and will be met with a world of sorrow when you are hit with filesystem corruption and lose all your data.

    RAID is for hardware fault tolerance, and your friend is 100% right in that you should also have an external backup. Whether it be burning to DVD, a USB drive, a NAS unit, whatever - backup your files!
  14. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    So, what good is raid? It doesn't sound like you would use it. I said I will raid with two hard drives and then use different backup sources to also back up.
  15. Justin

    Justin TS Rookie Posts: 942

    RAID is not designed to protect your data

    RAID is designed to minimize or remove the downtime involved when a hard drive fails


    User 1 has a system with an 80GB HDD, no RAID. He backs up his data daily

    User 2 has a system with 2 80GB HDD, in a RAID1. He backs up his data daily

    User 1 suffers a hard drive failure. User 1 must now replace the dead hard drive, reinstall his OS, reinstall his programs, reconfigure his settings and restore all his data back his backups. During this process, he's without the full use of his machine. This might take him hours at the least, days at the worst, to finish. Not to mention all the patches and updates he'll need to apply, programs he might have forgotten about, etc.

    User 2 suffers a hard drive failure. Because he has a RAID1 configuration, he simply replaces the hard drive that has died - and nothing else has been interrupted. He's down for only the time it takes him to put a replacement hard drive in. If it has to wait for a replacement, he can continue to use his system as normal - since the redundant disk is still functioning.

    That is where the primary advantage of RAID comes in. We can go more detailed as to what RAID levels are ideal for what scenarios or other purposes it has (performance vs redundancy), if you want.
  16. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 434

    User 3 like a lot of all computer users does not back up with no raid loses everything if complete hd failure or loses a partition if only one partition goes.
    User 4 has added protection because he has raid and didn't back up like most computer users and just adds another hd and has saved everything.
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