RAID Question

RWBRWB Icrontian
edited October 2005 in Hardware
I've setup RAID array's before, but I was wondering about this....

I have a 120GB and 250GB SATA HDD's, I want to buy another HDD identical to the 120GB HDD and put it in a RAID0 Array with the other 120GB HDD. But because RAID0 arrays are more easily destructable I was wandering if I could use the 250GB HDD as a mirrored drive similar to a RAID1 array so that if the RAID 0 array fails I don't have to really worry about much.

Know what I mean?

Comments

  • QeldromaQeldroma Arid ZoneAh Member
    edited October 2005
    RWB,

    The simple answer to your question is no.

    I think the best thing to do is to expain what these RAID conventions are and how they are normally implemented on the consumer market so you understand-

    RAID0 - is a striping convention where files are literally split-up between disks in hopes that once accessed the system can take advantage of both's capabilities. While in theory different drives could be used, it is much easier (and cheaper) for controllers to manage if they are the same- and so that is how it is specified. There is only one size, speed, cache, etc, to know for both drives.

    RAID1 - is a mirroring where the contents of one drive is exactly like that of the other. If you have two drives on one side, you are going to have slightly different data because each drive has to keep track of how it is storing data and stores that information on itself. This will be different from how a different type of drive on the other side keeps track of its data- hence violating the exact mirror concept. Having exact duplicate drives on both sides also has implementation and cost advantages.

    Hope that helps.

    :)
  • RWBRWB Icrontian
    edited October 2005
    Yes I know that, I was just hoping for a way to have a consistant backup of my files on teh RAID0 array without getting too expencive and getting a RAID5 array or RAID0+1
  • QeldromaQeldroma Arid ZoneAh Member
    edited October 2005
    RWB wrote:
    Yes I know that, I was just hoping for a way to have a consistant backup of my files on teh RAID0 array without getting too expencive and getting a RAID5 array or RAID0+1

    Actually, there is a great question there that I'd like to know the answer to myself. It is also a reason I don't bother to RAID0 at all (besides that studies show that RAID0 buys you very little real performance anyhow and multiplies your chance of failure).

    Perhaps someone who is familiar with RAID0 can address the issues of boot imaging back-ups and disk migrations.

    RAID5 is a pro method- but maybe the best one. It's not cheap and easy.
  • profdlpprofdlp The Holy City Of Westlake, Ohio
    edited October 2005
    Could you configure some sort of drive image software to do an automatic backup every night, or something like that?

    My experience has been that any RAID array is vulnerable in the sense that you are at the mercy of the RAID controller itself. If it chokes on you, you could well lose the whole shebang. No matter what else you do, I always recommend that you backup your crucial data - uncompressed - onto DVD or CDRW. It's a pain to have to reinstall Windows, but not nearly as much as losing all your (irreplaceable) data.
  • Mt_GoatMt_Goat Head Cheezy Knob Pflugerville (north of Austin) Icrontian
    edited October 2005
    profdlp wrote:
    Could you configure some sort of drive image software to do an automatic backup every night, or something like that?

    My experience has been that any RAID array is vulnerable in the sense that you are at the mercy of the RAID controller itself. If it chokes on you, you could well lose the whole shebang. No matter what else you do, I always recommend that you backup your crucial data - uncompressed - onto DVD or CDRW. It's a pain to have to reinstall Windows, but not nearly as much as losing all your (irreplaceable) data.
    prof has the best plan as it allows for the best possible performance and is cheapest in the long run. RAID-0 is good if you are useing it for your rendering and storage of such images but not so well suited for your OS. Manual or software enabled auto backups are the best way. RAID-0+1 is a waste as you loose any gains by the mirroring process and will only run as fast as the mirrored drive. RAID-5 isn't much better but RAID-10 is vastly superior but much more costly.
  • TexTex Dallas/Ft. Worth
    edited October 2005
    mtgoat wrote:
    RAID-0+1 is a waste as you loose any gains by the mirroring process and will only run as fast as the mirrored drive. RAID-5 isn't much better but RAID-10 is vastly superior but much more costly.

    Raid-5 is worse not better then either alternative performance wise. Its just cheaper.

    Not sure why you think raid-10 is vastly superior to raid-0+1? One is a raid-1 mirror of a raid-0 array and the other is a raid-0 stripe of a raid-1 array. Not that much differance really. Half a dozen of one and six of the other... The main differance is probably that most serious hardware controllers use raid-10 and most cheap software raid controllers use raid-0+1. But in "concept" I don't see that much to make one vastly superior over the other on the same hardware. Nor differant in price. Same number of disks mirrored etc... Only the controller is differant price wise.

    Cheers Goat

    Tex
  • QCHQCH Ancient Guru Chicago Area - USA Icrontian
    edited October 2005
    Only thing I can think of between 1+0 or 0+1... When the data is split and written to the drive and when it's coppied to the other drives.

    0+1 = Split the data and 1/2 to one drive, other half to the other drive, then the data is copied to the other two drives?

    1+0 = Data is split and 1/2 is copied to two drives and the other 1/2 goes to the other two drives?

    I have absolutely NO data to back that up, just my (simple) thought process. Is this correct?

    Raid 1+0 and 0+1 Explained
  • Mt_GoatMt_Goat Head Cheezy Knob Pflugerville (north of Austin) Icrontian
    edited October 2005
    Tex wrote:
    Raid-5 is worse not better then either alternative performance wise. Its just cheaper.

    Not sure why you think raid-10 is vastly superior to raid-0+1? One is a raid-1 mirror of a raid-0 array and the other is a raid-0 stripe of a raid-1 array. Not that much differance really. Half a dozen of one and six of the other... The main differance is probably that most serious hardware controllers use raid-10 and most cheap software raid controllers use raid-0+1. But in "concept" I don't see that much to make one vastly superior over the other on the same hardware. Nor differant in price. Same number of disks mirrored etc... Only the controller is differant price wise.

    Cheers Goat

    Tex
    My point was that in reality the fact that a true hardware controller (most raid 10 capable are) will give better performance than a software raid set-up and also thus the price difference also.

    My main point was that backups are the best solution in his case.
  • TexTex Dallas/Ft. Worth
    edited October 2005
    Wish you had been more clear as you said RAID-10 was vastly superior not what type of controller?

    I agree though that any raid does not replace regular backups.

    Tex
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