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Question about RAID 0+1 IS THIS POSIBLE?

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January 9, 2006 5:12:56 PM

I understand that you can make an array with different sized disk but you will lose space. Example: 120GB +160GB = 240GB (you lose 40gb)
Now, if i have 2 160GB Hds in a RAID 0 array making 1 320GB HD. Is it posible that if i put a 350GB HD i can make a 0+1 array between the raid 0 array (wich is like one disk) and the other disk wich has the same capacity or more than the array???

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January 9, 2006 7:37:05 PM

From what I have read, RAID 0+1 requires 4 drives. 2 make a striped set and the 2 others mirror each of the discs. I am not sure if there are RAID chipsets that will allow a 3 drive setup. I haven't found any, so please let me know what you find.
January 9, 2006 8:01:24 PM

yeah, raid 0+1 requires 4 drives. i'm also not too sure about being able to use different sized drives, i'm pretty sure the drives all must be the same capacity for raid to work
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January 9, 2006 8:34:15 PM

Intel's RAID controller has a 'special feature' to create what it calls 'matrix RAID' to both mirror and stripe on 2 drives. I doubt the matrix raid is set up to take a striped array and mirror a 3rd drive to it, but you can check with Intel if you'd like. I'm 99% certain that no controller without 'matrix raid' can do what you want - the matrix is your best bet.

You're correct - if you RAID 0 a 160g & 120g you'll get 240g with 40g of the 160 wasted. If you RAID 1 the same 2 drives you'll get 120g with the same 40 wasted.

While what you're asking is technically possible, I doubt any of the raid controllers can do it.

Mike.
January 10, 2006 5:42:09 AM

You can always use RAID 5 w/ 3 disks. It's a little faster than RAID 1 but not quite as fast as RAID 0 or 0+1. But you still get the redundancy of RAID 0+1 and plain 'ole 1. Just a suggestion. :-)

-mpjesse
January 10, 2006 9:38:47 PM

yes, i thinked of RAID 5 but my problem is the next one, ive no fear of one disk failing. My fear is if i have to move my array by force, not by will. If something happens to my motherboad im screwed. I´m in Argentina so not everybody has decent computers here, is not like i can go to a friend´s house and use my array in his pc, it´s possible that if he is not a computer fan like me he will not even know what sata is. So if I have an array and I have a perfect image of the entire disk in a single drive, i can use my array for performance and the single drive is a daily image backup in case my motherboard dies and i have to replace it with another one wich is not compatible.
I can use HD imaging software to duplicate my entire array to a larger disk but i´ll have to program it to do it every night, it will only take one hour at worst but if it could be done live while im in the pc it will be best.
So, finishing, i will use my array (160*2) and i will buy a 300GB HD, i´ll create a partition of 270GB to store my things and another partition with the rest of the space for windows, apps and games. I will setup an imaging software to make and exact copy of the 270GB partition to the 300GB HD every midnight (i can use the bios to startup my pc and sotware to shut it down after automaticly) so ill have a backup, and ill have the performance of RAID 0 with the security of RAID 1 and if i need to change PC i can destroy the array, put it in another one and recover the things from the other disk.

Thats my way, Im open to suggestions. And thanks to you all of you for trying to help.
January 12, 2006 2:06:40 PM

Just thought of something.

As long as your RAID 0 is on a hardware controller (mobo or add-on card) and you're not using Window's software RAID, you may be able to use Disk manager to mirror the RAID array to your extra drive using windows' Software RAID.



Mike.
January 12, 2006 3:07:05 PM

Fishmahn is right. Use the raid card to setup the raid 0 between the two smaller drives. Then in Windows you can setup a mirror between the raid 0 drive and the single 350gb. This will give you the +1. Tom's had a article "Unleashing RAID 5 Under WindowsXP" and this should allow mirroring in XP as well as raid 5 if you don't have windows 2000 or 2003.
January 12, 2006 3:30:12 PM

There's no good reason for 0+1 on a desktop other than just because! Fishmahn's idea sounds interesting though.
January 12, 2006 4:24:03 PM

As long as system does is not delayed till final mirror is complete, otherwise things could drag...
January 13, 2006 2:42:39 PM

I seem to recall when looking into some RAID stuff that non-server versions of windows only allow you to do RAID 0, not 1. We needed a quick temporary Mirrored array while we were fiddling with the server/network. I looked into the software option and ended up having to get a card because it was un-doable.
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