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[aclug-L] Re: RAID question?

[aclug-L] Re: RAID question?

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To: discussion@xxxxxxxxx
Subject: [aclug-L] Re: RAID question?
From: "Jonathan Hall" <flimzy@xxxxxxxxxx>
Date: Thu, 3 Oct 2002 11:54:53 -0500
Reply-to: discussion@xxxxxxxxx

That depends.  For most (all?) hardware RAID controllers, yes, they must be
the same size.

For Linux software RAID, no, they don't need to be the same size.  Although
for performance, they should be the same size, or multiples of the same

I've successfully RAIDed a 1g and 500mb drive using Linux software RAID
(long ago when those drives were mildly cool).

What it does in that case, is put 2 blocks on the 1gb drive for every 1
block on the 500mb drive.

Something like this:

    1gb                500mb
-----------    ---------------
1 2 4 5 7 8    3 6 9 . . .
 . . .

If you have mismatched size drives, I believe it will stripe up to the end
of the larger drive.  For instance:

    1gb            1.2gb
----------    ------------
...100 102   101 103 104
                   105 106 107
                    ... 119 120

So at the end of the virtual RAID disk, you lose the advantages of RAID,
because only one disk is being used.

----- Original Message -----
From: "David Carmichael" <dec29111@xxxxxxxxxxxxxxxx-spam>
To: <discussion@xxxxxxxxx>
Sent: Thursday, October 03, 2002 11:32 AM
Subject: [aclug-L] RAID question?

> Question about RAID ARRAY
> [ RAID 0 / Level 0 is also referred to as "striping".]
> While in a perfect world both harddrives would be the same size, make and
> model...
> _But_
>             MUST both drives in a RAID ARRAY be the same size, make and
> model??
> I have two WD drives one 40gb and one 39gb.
> I have an IDE RAID controller which I am currently only using as an add on
> IDE controller.
> --David
> -- This is the discussion@xxxxxxxxx list.  To unsubscribe,
> visit

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