User's Manual

volumes, availability or fault-tolerance is achieved by maintaining redundant data. Redundant data

includes mirrors (duplicate data) and parity information (reconstructing data using an algorithm).

• Performance — Read and write performance can be increased or decreased depending on the RAID

level you choose. Some RAID levels may be more appropriate for particular applications.

• Cost efficiency — Maintaining the redundant data or parity information associated with RAID volumes

requires additional disk space. In situations where the data is temporary, easily reproduced, or non-

essential, the increased cost of data redundancy may not be justified.

• Mean Time Between Failure (MTBF) — Using additional disks to maintain data redundancy also

increases the chance of disk failure at any given moment. Although this option cannot be avoided in

situations where redundant data is a requirement, it does have implications on the workload of the

system support staff within your organization.

• Volume — Volume refers to a single disk non-RAID virtual disk. You can create volumes using external

utilities like the O-ROM <Ctrl> <r>. Storage Management does not support the creation of volumes.

However, you can view volumes and use drives from these volumes for creation of new virtual disks

or Online Capacity Expansion (OCE) of existing virtual disks, provided free space is available. Storage

Management allows Rename and Delete operations on such volumes.

Choosing RAID Levels And Concatenation

You can use RAID or concatenation to control data storage on multiple disks. Each RAID level or

concatenation has different performance and data protection characteristics.

The following topics provide specific information on how each RAID level or concatenation store data as

well as their performance and protection characteristics:

• Concatenation

• RAID Level 0 (Striping)

• RAID Level 1 (Mirroring)

• RAID Level 5 (Striping With Distributed Parity)

• RAID Level 6 (Striping With Additional Distributed Parity)

• RAID Level 50 (Striping Over RAID 5 Sets)

• RAID Level 60 (Striping Over RAID 6 Sets)

• RAID Level 10 (Striping Over Mirror Sets)

• RAID Level 1-Concatenated (Concatenated Mirror)

• Comparing RAID Level And Concatenation Performance

• No-RAID