User's Manual
Understanding RAID Concepts 39
• 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
Concatenation
In Storage Management, concatenation refers to storing data on either one
physical disk or on disk space that spans multiple physical disks. When
spanning more than one disk, concatenation enables the operating system to
view multiple physical disks as a single disk.
Data stored on a single disk can be considered a simple volume. This disk
could also be defined as a virtual disk that comprises only a single physical
disk. Data that spans more than one physical disk can be considered a
spanned volume. Multiple concatenated disks can also be defined as a virtual
disk that comprises more than one physical disk.
A dynamic volume that spans to separate areas of the same disk is also
considered concatenated.
When a physical disk in a concatenated or spanned volume fails, the entire
volume becomes unavailable. Because the data is not redundant, it cannot be
restored by rebuilding from a mirrored disk or parity information. Restoring
from a backup is the only option.
Because concatenated volumes do not use disk space to maintain redundant
data, they are more cost-efficient than volumes that use mirrors or parity
information. A concatenated volume may be a good choice for data that is
temporary, easily reproduced, or that does not justify the cost of data
redundancy. In addition, a concatenated volume can easily be expanded by
adding an additional physical disk.