Users Guide

• 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
You can use RAID 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 store data as well as their performance and protection
characteristics:
• 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 0 (Striping)
RAID 0 uses data striping, which is writing data in equal-sized segments across the physical disks. RAID 0 does not provide data
redundancy.
RAID 0 characteristics:
• Groups n disks as one large virtual disk with a capacity of (smallest disk size) *n disks.
• Data is stored to the disks alternately.
• No redundant data is stored. When a disk fails, the large virtual disk fails with no means of rebuilding the data.
• Better read and write performance.
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Managing Storage Devices