Networking —

RAID 10

Sometimes RAID levels are combined to take advantage of the best of each. One such strategy is RAID 10, which combines RAID levels 1 and 0. In this configuration, four disks are required. As you might expect, the configuration consists of a mirrored stripe set. To some extent, RAID 10 takes advantage of the performance capability of a stripe set while offering the fault tolerance of a mirrored solution. As well as having the benefits of each though, RAID 10 also inherits the shortcomings of each strategy. In this case, the high overhead and the decreased write performance are the disadvantages. Figure 5 shows an example of a RAID 10 configuration. Table 3 provides a summary of the various RAID levels.

Figure 5 Disks in a RAID 10 configuration.


Table 3 Summary of RAID Levels

RAID Level

Description

Advantages

Disadvantages

Required Disks

RAID 0

Disk striping

Increased read and write performance. RAID 0 can be implemented with only two disks.

Does not offer any fault tolerance.

Two or more

RAID 1

Disk mirroring

Provides fault tolerance. Can also be used with separate disk controllers, reducing the single point of failure (called disk duplexing).

RAID 1 has a 50% overhead and suffers from poor write performance.

Two

RAID 5

Disk striping with distributed parity

Can recover from a single disk failure; increased read performance over a poor write single disk. Disks can be added to the array to increase storage capacity.

May slow down network during regeneration time, and may suffer from performance

Minimum of three

RAID 10

Striping with mirrored volumes striping;

Increased perfor mance with striping; offers mirrored fault tolerance.

High overhead as with mirroring.

Four