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Chapter 1 DX3000 and DX5000 System Description

Typical Configurations

Quantum DX3000 and DX5000 User’s Guide 11

RAID 5 Configuration 1 The RAID 5 configuration is the most common RAID level in use today.

RAID 5 minimizes the write bottlenecks of other RAID levels by

distributing parity stripes over a series of hard drives. In doing so it

provides relief to the concentration of write activity on a single drive,

which in turn enhances overall system performance. Instead of allowing

any one drive in the array to assume the risk of a bottleneck, all of the

drives in the array assume write activity responsibilities. The distribution

frees up the concentration on a single drive, improving overall subsystem

throughput.

The RAID 5 parity encoding scheme maintains the system’s ability to

recover any lost data should a single drive fail. This can happen as long as

no parity stripe on an individual drive stores the information of a data

stripe on the same drive. In other words, the parity information for any

data stripe must always be located on a drive other than the one on which

the data resides (see figure 8

Figure 6 RAID 5 Configuration

Drive 0 Drive 1 Drive 2 Drive 3 Drive 4

A0 A1 A2 A3

1 parity

B0 B1 B2

2 parity

C0 C1 3 parity C3 C4

4 parity

D2 D3 D4

0 parity

E1 E2 E3 E4

Data stripe

Data stripe A

Data stripe B

Data stripe C

Data stripe D

Data stripe E

Typical Configurations 1

The DX3000/DX5000 system has many advantages over typical tape

cartridge based systems such as faster data transfer, instant availability,

and greater reliability.

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Quantum DX5000 Betriebsanweisung Seite 29