Chapter 9: Managing Logical Drives and Hot Spares ā—74

Understanding Logical Drives

A logical drive is a group of physical disk drives that appears to your
operating system as a single drive that can be used for storing data.
A logical drive can c omprise one or more disk drives and can use part or
all of each disk driveā€™s capacity.
It is possible to include the same disk drive in two different logical
drives by using just a portion of the space on the disk drive in each, as
illustrated below.
Disk drive space that has been assigned to a logical drive is called a
segment. A segment can include all or just a portion of a disk driveā€™s
space. A disk drive with one segment is part of one logical drive, a disk
drive with two segments is part of two logical drives, and so on. A
segment can be part of only one logical drive. When a logical drive is
deleted, the segments that comprised it revert to available space (or free
segments).
A logical drive can include redundancy, depending on the RAID level
assigned to it. (See Understanding RAID on page 163 for more
information.)
Once a logical drive has been created, you can change its RAID level or
increase its capacity to meet changing requirements. You can also
protect y our logical drives by assigning one or more hot spar es to them.
(See page 90 for more information.)
Available
Space
Disk Drives (500 MB Each)
RAID 5 Logical Driv
e
R
AID 1 Logical Drive
250 MB
250 MB
250 MB 250 MB
250 MB
250 MB250 MB
250 MB
250 MB
250 MB
Segment (250 MB)Segment (250 MB)