HP AD510A HP StorageWorks 1500 Modular Smart Array installation guide (355901 - Page 23
enter Selective Storage Presentation SSP settings and, in the CLI, build Access Control Lists
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• Customize the RAID level and striping method to the type of data that will be stored on the LUN. For example, depending on the number of drives included in an array, the ACU may suggest RAID 6 (ADG) as the default RAID level, which offers a high level of fault tolerance and usable disk capacity, but at a significant cost to I/O performance. For comparable fault tolerance but higher performance, consider using RAID 1+0 when fault tolerance is desired and performance is more important than usable capacity. Reserve RAID 6 for situations when fault tolerance is desired, but usable capacity is more important than performance. • Set the ratio of read cache to write cache to prioritize writing in RAID 1, RAID 1+0, RAID 5, and RAID 6 (ADG) configurations to improve non-random write performance. • Set the controller rebuild priority to medium or high to minimize exposure during a drive rebuild. During a drive rebuild, limit I/O activity from the attached servers. • After configuring the LUNs, remember to: • Verify that all HBA connections to the MSA are recognized, including both paths in a multipath configuration. Each time the MSA is power-cycled, all active connections to the MSA are automatically detected and identified by their World Wide Port Name (WWPN). As needed, manually add the additional connections. Run the ACU or CLI from each host in the network to verify that each of its HBAs has been granted access to the MSA LUNs for that host. If both connections are not granted access, I/O cannot fail over to the redundant path. • Identify the operating system of each HBA connection to the MSA by setting the profile (also called Host Mode) of each connection. For example, on Windows systems set the profile to Windows. • Limit access to the LUNs to prevent unintended or unauthorized access. Although not required, HP strongly recommends this security measure. These settings are especially important in heterogeneous environments to prevent the same or different servers running different operating systems, and using a mix of HBAs from different vendors, from accessing the same LUN. For each HBA connection, indicate the LUNs that it can access. In the ACU, enter Selective Storage Presentation (SSP) settings and, in the CLI, build Access Control Lists (ACL). • In active/active multipath configurations, HP recommends disabling host-based Fibre Channel HBA load balancing. By default, MSA firmware balances the LUNs between the two MSA controllers. (Or optionally, you can manually specify the preferred controller path for each LUN.) If HBA load balancing is also enabled at the host, the host instructions will override the MSA instructions, resulting in additional processing time and reduced performance. • In Windows environments, HBA load balancing is set in the HP MPIO DSM Manager. • In Linux environments, HBA load balancing is set via a driver command line option. • Distribute ownership of the LUNs between the two MSA controllers in active/active multipath configurations. Choose one of the following: • Automatic load balancing (Default)-MSA firmware initially assigns ownership of all LUNs to one of the two MSA controllers, and then automatically re-assigns LUN ownership evenly between the controllers based on I/O loads of the LUNs. • Manual load balancing-Through the ACU or the CLI, indicate the preferred path (controller ownership) for each LUN. This method is recommended for environments that are load balancing from the host. HP StorageWorks 1500 Modular Smart Array installation guide 23