Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 66

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 2-34 Introduction to RAID