Non-Redundant Logical Drives (Raid 0); Raid 1 Logical Drives - Adaptec CDP-00278-01-A User Manual

Non-redundant Logical Drives (RAID 0)

A logical drive with RAID 0 includes two or more disk drives and provides data striping, where data is
distributed evenly across the disk drives in equal-sized sections. However, RAID 0 logical drives do not
maintain redundant data, so they offer no data protection.
Compared to an equal-sized group of independent disks, a RAID 0 logical drives provides improved I/O
performance.
Drive segment size is limited to the size of the smallest disk drive in the logical drive. For instance, an
array with two 250 GB disk drives and two 400 GB disk drives can create a RAID 0 drive segment of 250
GB, for a total of 1000 GB for the volume, as shown in this figure.
Disk Drive 1 250 GB
Disk Drive 2 250 GB
Disk Drive 3 400 GB
Disk Drive 4 400 GB
Disk Drives in Logical Drive

RAID 1 Logical Drives

A RAID 1 logical drive is built from two disk drives, where one disk drive is a mirror of the other (the
same data is stored on each disk drive). Compared to independent disk drives, RAID 1 logical drives
provide improved performance, with twice the read rate and an equal write rate of single disks. However,
capacity is only 50 percent of independent disk drives.
If the RAID 1 logical drive is built from different- sized disk drives, the free space, drive segment size is
the size of the smaller disk drive, as shown in this figure.
Proprietary and Confidential to PMC-Sierra, Inc.
Document No.: CDP-00278-01-A Rev. A, Issue:
Drive Segment Size
(Smallest Disk Drive)
Disk Drive 1 1 5 . . .
2 6 . . .
Disk Drive 2
Disk Drive 3
3 7 . . .
Disk Drive 4 4 8 . . .
RAID 0 Logical Drive = 1000 GB
maxView Storage Manager User's Guide
997
998
999
Unused Space = 150 GB
1000
Unused Space = 150 GB
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