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In highly consolidated environments, SAP HANA and other databases and applications compete for storage resources. When creating and presenting storage volumes to metro node, consider Quality of Service (QoS) features such as host I/O limits and service levels for the underlying back-end storage arrays.
The host I/O limits feature controls “noisy neighbors” and protects the performance of the SAP HANA system. Host I/O limits can be effective in consolidated environments if an overload on the storage resources affects the performance of critical applications such as production installations. To protect the performance of SAP HANA production systems, limit the total IOPS or bandwidth, which might otherwise consume a large portion of the system’s resources. To limit the total IOPS, configure host I/O limits on the underlying back-end storage array for the storage volume LUNs and the datastores of either non-SAP HANA applications or SAP HANA nonproduction systems that are presented to the metro node.
PowerStore systems can provide the required performance levels using the performance policies on the volumes. PowerMax and VMAX All Flash arrays provide the required performance using service levels. Service levels enable users to insulate specific storage groups from any performance impact by other noisy neighbor applications. Critical applications can be assigned to higher service levels such as diamond, platinum, or gold, which allow these storage groups to use all available resources at all times.
See References for links to the configuration best practices guide for your certified Dell underlying storage.
SAP HANA Native Storage Extension (NSE) is a general-purpose, integrated warm data store in SAP HANA that lets you manage less-frequently accessed data without fully loading it into memory. SAP HANA NSE can be used with metro node with the underlying physical certified enterprise storage system. NSE integrates flash-drive based database technology with the SAP HANA in-memory database for an improved price-performance ratio:
Note: NSE is subject to certain functional restrictions. For more information, see SAP Note 2771956: SAP HANA NSE Functional Restrictions with HANA 2.0 SPS 04 and SAP Note 2927591: SAP HANA NSE Functional Restrictions with HANA 2.0 SPS 05 (access requires SAP login credentials).
The following figure shows the difference between standard SAP HANA in-memory storage and the storage that is offered with NSE:
The amount of main memory limits the capacity of a standard SAP HANA. By using SAP HANA NSE, customers can bypass these limits by storing warm data on PowerStore storage. Paging operations require a relatively small amount of SAP HANA memory for the NSE buffer cache because the buffer cache can handle up to eight times the size of warm data on disk. For example, a 2 TB SAP HANA system without NSE equates to a 1 TB database in memory. With NSE and the addition of a 500 GB buffer cache, you can expand your 1 TB database to a 5 TB database consisting of 1 TB of hot data, 4 TB of warm data, and a 500 GB buffer cache to page data between memory and disk. The default buffer cache is set to 10 percent of SAP HANA memory.
Hot data is “column loadable,” which means that it resides completely in-memory for fast processing and is loaded from disk into SAP HANA memory in columns. By using SAP HANA NSE, you can specify certain warm data as ‘page loadable.’ This data is loaded into memory page by page as it is needed for query processing. Unlike column-loadable data, page-loadable data does not need to reside completely in memory.
The following figure shows the SAP HANA database with NSE:
NSE reduces the memory footprint for page-loadable data. The database is partly in memory and partly on disk. You can use the PowerStore storage system together with SAP HANA NSE to substantially increase SAP HANA data capacity and reduce TCO.
NSE is integrated with other SAP HANA functional layers, such as the query optimizer, query execution engine, column store, and persistence layers.
For more information about SAP HANA NSE and related topics, see the SAP white paper SAP HANA Native Storage Extension.