21Understanding arrayswww.gateway.comOptimization and drive selection for RAID 5arraysTypical RAID 5 implementations require a number of steps to write the datato the drives. In order to optimize your system performance based on the typeof writes you expect in your operation, we have provided detailed informationon optimizing the performance using full strip write operations in an appendix(see “Optimizing RAID 5 Write Performance” on page 227).If you intend to setup a RAID 5 array and want to consider optimumperformance, you will need to consider the number of drives, parity drives, andchunk size. You should review the information provided in “Optimizing RAID5 Write Performance” on page 227. Additional information is provided at theappropriate step during configuration.RAID Level 10 RAID 10 is defined as mirrored stripe sets (also known asRAID 0+1). You can build RAID 10 either directly throughthe RAID controller (depending on the controller) or bycombining software mirroring and controller striping (calledRAID 01).RAID Level 50 This RAID level is a combination of RAID level 5 and RAIDlevel 0. Individual smaller RAID 5 arrays are striped, to givea single RAID 50 array. This can increase the performanceby allowing the controller to more efficiently clustercommands together. Fault tolerance is also increased, asone drive can fail in each individual array.Sub-array In RAID 50 applications, this is the name given to theindividual RAID 5 arrays that are striped together. Eachsub-array has one parity drive.
