Maximizing Storage Capacity; Raid Levels And Capacity - Lenovo ThinkServer RD240 Software User's Manual

RAID
Level Performance
50 RAID 50 works best when used with data that requires high reliability, high request
rates, and high data transfer. It provides high data throughput, data redundancy, and
very good performance. Spanning increases the capacity of the virtual drive and
improves performance by doubling the number of spindles. The system performance
improves as the number of spans increases. (The maximum number of spans is eight.)
As the storage space in the spans is filled, the system stripes data over fewer and fewer
spans and RAID performance degrades to that of a RAID 1 or RAID 5 drive group.
60 RAID 60 works best when used with data that requires high reliability, high request
rates, and high data transfer. It provides high data throughput, data redundancy, and
very good performance. Spanning increases the capacity of the virtual drive and
improves performance by doubling the number of spindles. The system performance
improves as the number of spans increases. (The maximum number of spans is eight.)
As the storage space in the spans is filled, the system stripes data over fewer and fewer
spans and RAID performance degrades to that of a RAID 1 or RAID 6 drive group.
RAID 60 is not well suited to tasks requiring a lot of writes. A RAID 60 virtual drive has
to generate two sets of parity data for each write operation, which results in a significant
decrease in performance during writes. Drive performance is reduced during a drive
rebuild. Environments with few processes do not perform as well because the RAID
overhead is not offset by the performance gains in handling simultaneous processes.
2.6.3

Maximizing Storage Capacity

RAID
Level Capacity
0 RAID 0 (striping) involves partitioning each drive storage space into stripes that can
vary in size. The combined storage space is composed of stripes from each drive.
RAID 0 provides maximum storage capacity for a given set of drives.
1 With RAID 1 (mirroring), data written to one drive is simultaneously written to another
drive, which doubles the required data storage capacity. This is expensive because
each drive in the system must be duplicated.
Storage capacity is an important factor when selecting a RAID level.
There are several variables to consider. Striping alone (RAID 0) requires
less storage space than mirrored data (RAID 1) or distributed parity
(RAID 5 or RAID 6). RAID 5, which provides redundancy for one drive
failure without duplicating the contents of entire drives, requires less
space then RAID 1.
storage capacity.
Table 2.15

RAID Levels and Capacity

RAID Configuration Strategies
Table 2.15 explains the effects of the RAID levels on
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