Lenovo ThinkServer RD230, Software User'S Manual

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2-34 Introduction to RAID
Each type of data stored in the disk subsystem has a different frequency
of read and write activity. If you know the data access requirements, you
can more successfully determine a strategy for optimizing the disk
subsystem capacity, availability, and performance.
Servers that support video on demand typically read the data often, but
write data infrequently. Both the read and write operations tend to be
long. Data stored on a general-purpose file server involves relatively
short read and write operations with relatively small files.
2.8.1 Number of Drives
Your configuration planning for the SAS RAID controller depends in part
on the number of drives that you want to use in a RAID drive group.
The number of drives in a drive group determines the RAID levels that
can be supported. Only one RAID level can be assigned to each virtual
drive.
2.8.2 Drive Group Purpose
Important factors to consider when creating RAID drive groups include
availability, performance, and capacity. Define the major purpose of the
drive group by answering questions related to these factors, such as the
following, which are followed by suggested RAID levels for each situation:
•
Will this drive group increase the system storage capacity for
general-purpose file and print servers? Use RAID 5, 6, 10, 50, or 60.
•
Does this drive group support any software system that must be
available 24 hours per day? Use RAID 1, 5, 6, 10, 50, or 60.
•
Will the information stored in this drive group contain large audio or
video files that must be available on demand? Use RAID 0 or 00.
•
Will this drive group contain data from an imaging system? Use
RAID 0, 00, or 10.
Fill out Table 2.16 to help you plan the drive group configuration. Rank
the requirements for your drive group, such as storage space and data