Navisphere Command Line Interface (CLI) Reference - VMware Communities

Basic CommandsCaching recommendations for different RAID typesRAID type Write caching Read cachingRAID 0 Acceptable RecommendedRAID 1 Acceptable RecommendedRAID 1/0 Acceptable RecommendedRAID 3 * Recommended RecommendedRAID 5 Highly recommended RecommendedRAID 6 Highly recommended RecommendedDisk Acceptable RecommendedHot spare Not Allowed Not Allowed* For RAID 3, write caching is supported only on CX3 series or CX series storage system runningFLARE version 02.06.xxx.x.xxx or higher, or a dual-SP AX4-5 series storage system runningNavisphere Manager. Read caching is only supported on a CX3 series, CX series, or a dual-SPAX4-5 series storage system running Navisphere Manager.Note: LUNs cannot use write caching until you enable the storage-systemwrite cache (page 260). LUNs cannot use read caching until you enable theread cache for the SP that owns the LUN (page 86 for RAID group storagesystems). When binding RAID 1/0 LUNs, the order in which you selectmodules is important. The first module you select is the first part of themirror’s primary image and the second module is the first part of themirror’s secondary image; the third module is the second part of the primaryimage, the fourth module is the second part of the secondary image; and soon for any other modules in the LUN. In other words, the first and secondmodules selected are a pair of peer image parts, the third and fourth modulesare another pair of peer image parts, and so on.When a LUN is assigned to an SP, its state becomes assigned, and thestate of its disk modules become enabled when you use the SP thatowns the LUN as the communications path to the chassis.If you need to change the description (RAID type) or stripe sizeparameters, you must unbind the LUN (page 286), and then rebind itwith the correct parameters. If you need to change the maximumrebuild time, read cache state, or write cache state, use the chgluncommand (page 92).82 EMC Navisphere Command Line Interface (CLI) Reference