Adaptec 2130SLP User Guide - Page 165

Understanding Drive Segments, RAID 0 (Non-RAID Logical Drives

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Appendix D: Understanding RAID ● 164 Understanding Drive Segments A drive segment is a disk drive or portion of a disk drive that is used to create a logical device. A disk drive can include both RAID segments (segments that are part of a logical drive) and available segments. Each segment can be part of only one logical device at a time. If a disk drive is not part of any logical device, the entire disk is an available segment. RAID 0 (Non-RAID Logical Drives) A logical drive with RAID 0 includes two or more disk drives (maximum twelve) and provides data striping, where data is distributed evenly across the disk drives in equal-sized sections. RAID 0 logical drives do not maintain redundant data, so they offer no data protection. However, compared to an equal-sized group of independent disks, a RAID 0 logical drive provides improved I/O performance. Drive segment size is limited to the size of the smallest disk drive in the logical drive. For instance, a logical drive 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 below. Disk Drive 1 250 GB Drive Segment Size (Smallest Disk Drive) Disk Drive 2 250 GB Disk Drive 3 400 GB Disk Drive 4 400 GB Disk Drives in Logical Drive Disk Drive 1 1 5 ... 997 Disk Drive 2 2 998 6 ... Disk Drive 3 3 999 7 ... Not Used Unused Space: 150 GB Disk Drive 4 4 8 ... 1000 Not Used Unused Space: 150 GB RAID 0 Logical Drive = 1000 GB

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Appendix D: Understanding RAID
164
Understanding Drive Segments
A
drive segment
is a disk drive or portion of a disk drive that is used to
create a logical device. A disk drive can include both
RAID segments
(segments that are part of a logical drive) and available segments. Each
segment can be part of only one logical device at a time. If a disk drive is
not part of any logical device, the entire disk is an available segment.
RAID 0 (Non-RAID Logical Drives)
A logical drive with RAID 0 includes two or more disk drives
(maximum twelve) and provides data
striping
, where data is distributed
evenly across the disk drives in equal-sized sections.
RAID 0 logical drives do not maintain redundant data, so they offer no
data protection. However, compared to an equal-sized group of
independent disks, a RAID 0 logical drive provides improved I/O
performance.
Drive segment size is limited to the size of the smallest disk drive in the
logical drive. For instance, a logical drive 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 below.
Disk Drive 1
Disk Drive 2
Disk Drive 3
Disk Drive 4
250 GB
250 GB
400 GB
400 GB
Disk Drives in Logical Drive
Disk Drive 1
Disk Drive 2
Disk Drive 3
Disk Drive 4
RAID 0 Logical Drive = 1000 GB
1
2
3
4
Not Used
Not Used
5
6
7
8
1000
999
998
997
...
...
...
...
Unused Space: 150 GB
Unused Space: 150 GB
Drive Segment Size (Smallest Disk Drive)