Adaptec CDP-00278-02-A Guide de l'utilisateur télécharger pdf (Page 119)

RAID 5 Logical Drives

A RAID 5 logical drive is built from a minimum of three disk drives, and uses data striping and parity

data to provide redundancy. Parity data provides data protection, and striping improves performance.

Parity data is an error-correcting redundancy that's used to re-create data if a disk drive fails. In RAID

5 logical drives, parity data (represented by Ps in the next gure) is striped evenly across the disk drives

with the stored data.

Drive segment size is limited to the size of the smallest disk drive in the logical drive. For instance, an

array with two 250 GB disk drives and two 400 GB disk drives can contain 750 GB of stored data and

250 GB of parity data, as shown in this gure.

Unused Space = 150 GB

Disk Drive 1

Disk Drive 2

Disk Drive 3

Disk Drive 4

250 GB

400 GB

Drive Segment Size

(Smallest Disk Drive)

Disk Drive 2

Disk Drive 3

Disk Drive 4

Disk Drive 1

Unused Space = 150 GB

Disk Drives in Logical Drive

RAID 5 Logical Drive = 750 GB plus Parity

P1 4 . . .

7482 5 . . .

7493 P . . .

750P 6 . . .

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Adaptec CDP-00278-02-A Guide de l'utilisateur Page 119