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Maximizing Capacity

RAID 0 achieves maximum drive capacity, but does not provide data redundancy. Maximum drive capacity for each RAID level is shown below. original equipment manufacturer (OEM) level firmware that can span up to four logical drives is assumed. Table 7-7 displays the drives required, and capacity for the various RAID levels.

Ta b l e 7 - 7 . D r i v e s a n d C ap a c i t i e s f o r E a ch R A I D Le ve l

RAID

Description

Drives

Capacity

Level

 

Required

 

 

 

 

 

 

0

Striping without

1

– 32

(Number of disks) X (capacity of

 

parity

 

 

smallest disk)

 

 

 

 

 

1

Mirroring

2

 

(Capacity of smallest disk) X (1)

 

 

 

 

 

5

Striping with

3

– 32

(Number of disks) X (capacity of

 

floating parity

 

 

smallest disk) - (capacity of 1

 

drive

 

 

disk)

 

 

 

 

 

10

RAID 1 and

4

– 16

(Number of disks) X (capacity of

 

striping

(Must be a

smallest disk) / (2)

 

 

multiple of

 

 

 

2)

 

 

 

 

 

 

50

RAID 5 and

6

– 256

(Number of disks) X (capacity of

 

striping

(Must be a

smallest disk) – (capacity of 1

 

 

multiple of

disk X number of arrays)

 

 

arrays)

 

 

 

 

 

 

Maximizing Drive Availability

You can maximize the availability of data on the physical disk drive in the logical array by maximizing the level of fault tolerance. The levels of fault tolerance provided by the RAID levels are shown in Table 7-8.

Ta b l e 7 - 8 . Fa u l t Tol er an c e Fea t u r es f o r R A I D Le v el s 0, 1 a n d 5

RAID

Fault Tolerance Protection

Level

 

0No fault tolerance

1Disk mirroring, which provides 100% data redundancy.

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Configuring PERC 3

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Dell 3 manual Maximizing Capacity, Maximizing Drive Availability, Description Drives Capacity Level Required