RAID greater than 2TB on Fedora Core 3
Robin Laing
Robin.Laing at drdc-rddc.gc.ca
Mon Apr 4 16:42:25 UTC 2005
Jeff Vian wrote:
> On Mon, 2005-04-04 at 11:13 -0400, Scot L. Harris wrote:
>
>>On Mon, 2005-04-04 at 10:45, Masopust Christian wrote:
>>
>
> Your description is good, but slightly flawed in the raid5 description.
>
> A raid5 configuration loses exactly one drive for available space no
> matter how many drives are involved.
> If the array contains 3 drives it loses 1/3 of the total drive space.
> If it instead contains 10 drives it only loses 1/10 the drive space.
> Thus the 20% figure is correct only in a case where the array contains 5
> physical drives.
>
> This is because of the parity redundancy on raid5 that makes it possible
> to totally lose 1 drive and still lose no data.
>
> The OP did not state how many physical drives he has in the array, so I
> cannot conjecture whether the usable space (2TB) is correct or not.
>
And a 300GB drive doesn't have 300GB of available space once it is
formatted.
--
Robin Laing
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