SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide

Transcription

1 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide Abstract This document provides best-practices and configuration guidelines for Dell EMC XC Series Appliances and XC Core Systems for SAP HANA deployment using 14th generation PowerEdge technology and Nutanix software. December 2018 Dell EMC Best Practices

2 Revisions Revisions Date September 2018 September 2018 December 2018 Description Initial release Minor updates. Added new image with added node. The information in this publication is provided as is. Dell Inc. makes no representations or warranties of any kind with respect to the information in this publication, and specifically disclaims implied warranties of merchantability or fitness for a particular purpose. Use, copying, and distribution of any software described in this publication requires an applicable software license Dell Inc. or its subsidiaries. All Rights Reserved. Dell, EMC, Dell EMC and other trademarks are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be trademarks of their respective owners. Dell believes the information in this document is accurate as of its publication date. The information is subject to change without notice. 2 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

3 Table of contents Table of contents Revisions... 2 Table of contents... 3 Executive summary Introduction Objectives Audience Terminology Technology overview Dell EMC XC Family Dell EMC XC Family architecture SAP HANA SAP HANA on Dell EMC XC Family Cluster architecture SAP HANA VM configuration Storage configuration CPU configuration Memory configuration Drives layout Network configuration Best practices and recommendations Prerequisites Design recommendation CPU and memory Network Storage High availability Additional settings VM recommendation SAP HANA sizing considerations Health check and performance monitoring Health check Software update Performance monitoring References Dell EMC XC Family SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

4 Table of contents 5.2 Nutanix SAP HANA A Appendix A.1 SAP HANA cluster set up used for certification A.2 Certified configuration SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

5 Executive summary Executive summary NOTE: The information in this document applies to both Dell EMC XC Series Appliances, and the Dell EMC XC Core System offering. Sections or information that apply to only one of the offerings (XC Series or XC Core) will be called out explicitly. This document provides all necessary guidelines and best practices to get the best of your SAP HANA deployment on Dell EMC XC Family devices, which include both XC Series Appliances and XC Core Systems and Nutanix AHV. The Dell EMC XC Family is a hyper-converged solution that combines storage, compute, networking, and virtualization using industry-leading Dell EMC PowerEdge servers and Nutanix software. By combining the hardware resources from each server appliance into a shared-everything model for simplified operations, improved agility, and greater flexibility, Dell EMC, and Nutanix together deliver simple, cost-effective solutions for enterprise workloads. The XC Family devices are hypervisor agnostic and support your choice of hypervisor. With a focus on easeof-use and the ability to rapidly deploy multiple virtualized workloads, the XC Family is the preferred platform for many enterprises and midmarket customers alike. The XC Family devices use the Nutanix Distributed Storage Fabric (DSF), which delivers a unified pool of storage from all appliances across the cluster, using techniques including mirroring, replication, auto-tiering, error detection, failover, and automatic recovery. XC Family delivers storage through multiple protocols such as NFS, SMB, and iscsi while using standard network infrastructure. 5 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

6 Introduction 1 Introduction The Dell EMC XC Family integrates 14th generation PowerEdge server technology and Nutanix software to provide enterprise-class, infrastructure solutions for virtualized environments. The XC Family incorporates many advanced software technologies that power leading cloud infrastructures and include key features such as: Hyper-converged Seamlessly integrates server and storage resources in a self-healing system Software defined and distributed - Allows an IT professional to perform automatic software deployment anywhere with a single click. Scale-out Increase performance and/or capacity one node at a time, even across multiple generations Automation and analytics Extensive automation and rich system-wide monitoring 1.1 Objectives This paper documents: An overview of Dell EMC XC Series Appliances and XC Core Systems An overview of SAP HANA Dell EMC XC Family cluster configuration for SAP HANA SAP HANA sizing consideration Best Practices 1.2 Audience The document is intended for SAP HANA administrators, system administrators, storage administrators, and presales architects who design mission-critical SAP HANA systems to be deployed on Dell EMC XC Family devices. You should have some knowledge of XC Family devices and Nutanix software. 1.3 Terminology Useful terminology Term CVM DSF idrac NUMA Software-defined XC Family cluster LVM Description Controller Virtual Machine Distributed Storage Fabric Integrated Dell Remote Access Controller for remote server management Non-Uniform Memory Access Software-defined delivers all services through software using proven Dell EMC hardware. An XC Family cluster is a hyper-converged infrastructure solution that consolidates compute and storage into a single integrated appliance and creates a distributed virtual computing platform. Each node in the cluster runs an industry standard hypervisor and all the appliances work together to form a cluster which is scalable. Linux Logical Volume Manager 6 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

7 Technology overview 2 Technology overview 2.1 Dell EMC XC Family The Dell EMC XC Family devices are a hyper-converged solution that combines storage, compute, networking, and virtualization into an industry-proven appliance based on an x86 Dell PowerEdge server running Nutanix software. In addition, it is worth noticing the devices are not just off the shelf PowerEdge. The processor, memory, drives, firmware, and BIOS are tailored for Nutanix. By combining the hardware resources from each device into a shared-everything model for simplified operations, improved agility, and greater flexibility, Dell EMC, and Nutanix together deliver simple, cost-effective solutions for enterprise workloads. Nutanix Distributed Storage Fabric (DSF) delivers a unified pool of storage from all nodes across the cluster, using techniques including striping, replication, auto-tiering, error detection, failover, and automatic recovery. The XC Family architecture is a scalable cluster of high-performance appliances each running a standard hypervisor and containing processors, memory, and local storage (consisting of SSD, NVMe, or combination of both drives). The CVM running on each node aggregates the storage resources and make it available to all hosts through a fault tolerant architecture. Each appliance runs virtual machines just like a standard hypervisor host. XC Family architecture 2.2 Dell EMC XC Family architecture Dell EMC XC Family provides a hyper-converged platform that uses Distributed Storage Fabric to share and present local storage to all the virtual machines in the cluster. The general XC Family architecture is shown in Figure 2. 7 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

8 Technology overview The nodes easily scale without the constraints of traditional storage. DSF virtualizes the storage across all nodes and presents the same to the hypervisor as one large pool of shared storage. The DSF replicates writes synchronously to at least one other XC Family node to ensure cluster resiliency and availability. Local storage for each XC Family node in the architecture is presented as one large pool of shared storage to the hypervisor. Data Locality of an XC Family node can keep compute and storage close together that helps in consistent performance and availability of the data. In addition, DSF virtualizes local storage from all appliances into a unified pool. DSF uses local SSDs and disks from all nodes to store virtual machine data. Virtual machines running on the cluster write data to DSF as if they were writing to shared storage. Dell EMC XC Family offers you choice of hypervisors without being locked-in. The Nutanix CVMs are virtual machines running on AHV hosts. They have direct control of the drives on the AHV hosts. They come preconfigured with modest settings so that you can start using the storage platform without much startup time. 2.3 SAP HANA SAP HANA is an in-memory data platform that is deployable as an on-premise appliance, or in the cloud. It is a revolutionary platform that is best suited for performing real-time analytics and developing and deploying real-time applications. The data is kept in the RAM of one or multiple SAP HANA worker hosts. All database operations (reads, inserts, updates, or deletes) are performed in the main memory of the host. This feature differentiates SAP HANA from traditional databases, where only a part of the data is cached in RAM and the remaining data resides on disk. To ensure that the SAP HANA database can be restored to its most recent committed state, persistent storage is used to provide a fallback if there is failure. 8 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

9 SAP HANA on Dell EMC XC Family 3 SAP HANA on Dell EMC XC Family Dell EMC XC Family supports up to three SAP HANA production VMs on a quad socket XC940 node and one SAP HANA production VM dual socket XC740xd node. The minimum number of recommended nodes for SAP HANA production scenario on a XC Family cluster are 4 nodes (3 active nodes + 1 standby node). This ensures the high availability of HANA VMs during one node failure. In the following sections, we discuss the recommended architecture for SAP HANA systems on Dell EMC XC Family devices. 3.1 Cluster architecture The Dell EMC XC Family cluster for SAP HANA consists of two socket XC740xd nodes or four socket XC940 nodes. Dell EMC recommends a minimum of four nodes and the mixing of two socket and four socket nodes is allowed within a cluster. This approach provides flexibility as you can start small and scale based on your requirements. The cluster architecture shown in Figure 3 consists of a mix of both 2-socket and 4-socket nodes. Here, one XC940 node and two XC740xd nodes were part of active nodes, with one SAP HANA production system per socket. For example, the XC940 node was hosted with three production HANA VMs and the XC740xd node was hosted with one production HANA VM. The fourth node (XC940) was a stand-by node. This node must have equivalent compute resources available to accommodate the SAP HANA VMs during node failure scenarios. Dell EMC XC Family cluster set up for SAP HANA 9 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

10 SAP HANA on Dell EMC XC Family Figure 3 represents one of the Dell EMC XC Family cluster configurations that is supported for SAP HANA deployments. The cluster is formed using two XC740xd nodes and two XC940 nodes with 3 active nodes and 1 standby node for HA. Dell EMC representatives are available to assist in sizing and designing the cluster configuration based on customer requirements. 3.2 SAP HANA VM configuration For production HANA systems on Dell EMC XC Family nodes, Dell EMC recommends one HANA VM per socket, considering one dedicated socket for CVM. For a quad socket node, you can host three production HANA VMs per node. For a dual socket node, you can host one production HANA VM per node. For nonproduction HANA systems, you can allocate one HANA VM with half a node socket. You can host three HANA nonproduction VMs on dual socket node and seven host HANA nonproduction VMs on the quad socket node. Figure 3 shows an XC Family cluster configured with five SAP HANA production VMs. Three HANA production VMs are hosted on an XC940 node with one HANA production VM per XC740xd node. Each of these VMs are set with host affinity to meet the above configuration. 3.3 Storage configuration All HANA VM storage was created by allocating number of vdisks (virtual disk) from the cluster storage pool based on the HANA memory size and database storage requirement. This can be performed using Nutanix PRISM VM update option. On each VM, HANA data volume and log volumes were created by adding four vdisks each. LVM is used to create two separate volume groups, each volume group is created using physical volumes. On each of these two volume groups, two logical volumes are created with the stripe size of 64 KB and then mounted to HANA data volumes and HANA log volumes. More details on LVM and volume groups are mentioned in VM recommendation section. 3.4 CPU configuration Dell EMC XC Family is SAP HANA certified for dual sockets and quad sockets CPUs with Intel Xeon Gold processors 6126 or above or Intel Xeon Platinum processors with greater performance. Hyper-threading is a hardware technology on Intel processors that enables a physical processor core to act like two processors. In general, there is a performance advantage of enabling hyper-threading on the newer Intel processors. Dell EMC does not recommend sharing of CPU sockets between SAP HANA production VMs (NUMA node sharing). Dell EMC recommends using only 1 VM deployed on dual socket node (Dell EMC XC740xd) and 3 VMs on quad socket node (Dell EMC XC940). In addition, Dell EMC recommends that you set NUMA node affinity so that all the cores of single socket are entirely allocated to a single VM. 10 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

11 SAP HANA on Dell EMC XC Family 3.5 Memory configuration With the NUMA architecture, each processor has its local memory and can also access the non-local memory of the other processors over an advanced memory controller. Even though this is a high-performance connection, access to local memory is always faster than access to the non-local memory of the other processors. The memory is equally divided and assigned to the VM when an XC740xd and the VM gets 50 percent of the memory. With the XC940, the memory is divided to four equal chunks and allocated to three VMs. 3.6 Drives layout The XC940 and XC740xd nodes support 24 drives (mix of SSDs and NVMe drives are supported). Based on the capacity requirement, you can populate the nodes to achieve enough storage. Populate the NVMEs with SSDs to achieve better IO performance. 3.7 Network configuration Dell EMC XC Family supports both 10 GbE and 25 GbE networks for communication between the nodes, with 10 Gbe minimum recommended network configuration. For better performance of SAP HANA systems, you can consider a 25 GbE network with NVMe drives. Dell EMC recommends keeping the same MTU size for all HANA VMs within the XC Family cluster. Mismatch in MTU size between hosts and VM would lead to network instability and communication issues. Network components Components Data and management network XC Family internode connection (VM traffic) idrac inband network Cabling Description 10 GbE switch 10 GbE switch 1 GbE switch CAT6 coaxial and 10 G twin axial 11 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

12 Best practices and recommendations 4 Best practices and recommendations To deliver the best performance for SAP HANA on hyper-converged infrastructure on production environment, you must verify specific settings and enable certain options. This section provides the best practices for improving the performance of SAP HANA system. 4.1 Prerequisites The following are the prerequisites for a successful SAP HANA solution: Latest version of AHV hypervisor and Nutanix AOS is recommended. Apply operating system level patches and settings for HANA VMs as in the SAP note (SLES). For a supported Operating System for SAP HANA, go to Verify that the XC Family cluster is in healthy state by performing health check option available from Nutanix Prism. Details on health check and performance monitoring can be found in Health check and performance monitoring. 4.2 Design recommendation There are certain parameters for you to consider while designing production SAP HANA systems on the XC Family hyper-converged infrastructure CPU and memory This section outlines the best practices for CPU and memory. Do not assign a socket to any other VMs (or sharing resources) that are allocated to a controller VM. For dual socket node, Dell EMC recommends only 1 VM and for quad socket node, and a maximum of 3 VMs. Dell EMC does not recommend using multiple HANA production VMs sharing the same socket. The memory should be equally divided among the VMs in such a way that it is not shared. Over commitment of memory would affect SAP HANA performance and therefore not recommended. - For XC740xd, half of the total memory available is allocated to a single SAP HANA VM. - For XC940, minimum 1/4th of the total memory available is allocated to a single SAP HANA VM. For production HANA systems, ensure that following guidelines are followed: - For dual socket platform - one VM with one socket worth of CPU and memory - For quad socket platform Maximum three VMs with one socket worth of CPU and memory for each. If there are a fewer number of VMs, then you can assign more cores to the VMs. - Example: 2 VMs on quad core- First VM with 1 socket worth of CPU and memory, second VM with 2 sockets worth of CPU and memory. For non-production HANA systems, configure VMs with half a socket worth of CPU and memory. Note: This might lead to performance degradation. 12 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

13 Best practices and recommendations Network This section outlines the best practices for networking. SAP HANA network communication must be separated in different logical networks for internode, storage, backup, replication, client, and so on. When selecting and setting up SAP HANA production systems, follow the SAP HANA networking recommendations as described in SAP HANA Network Requirements, which involves ensuring the availability of enough physical and virtual network interfaces. Based on the SAP HANA production environment requirement, adequate VM network interfaces should be configured for the various logical network configurations. These network requirements can be met using Dell EMC XC Family by configuring the nodes with adequate number of physical network interfaces. Refer the Dell EMC XC Family data sheet for more details. For Dell EMC XC Family networking best practices see Storage This section outlines the best practices for storage. For sizing the usable storage on Dell EMC XC Family clusters, Dell EMC recommends the following: - Use the SAP Quick Sizer tool to determine the required capacity for the SAP HANA data and log devices. If the sizing details are not available, Dell EMC recommends configuring the usable storage size based on SAP HANA database memory footprint. The usable storage space available is recommended to be 4 * the SAP HANA database memory footprint. For more details on sizing, see the latest available SAP note on HANA sizing consideration High availability The minimum number of nodes that are recommended for SAP HANA cluster with production systems are 4 nodes (3 active and 1 standby) to achieve high availability for the VMs. Nutanix recommends planning for failover capacity in the form of N+1. Dell EMC recommends following the steps in the Prism Web Console Guide to configure the cluster for high availability Additional settings Dell EMC does not recommend enabling core data service features like compression, deduplication, and EC- X on the storage container that holds the production database. To ensure maximum performance and availability, adjust the following hypervisor settings: 1. To allow for energy saving when a CPU is idle, you can instruct the CPU to enter a low-power mode. There are various power modes available to each CPU; the various power modes are referred to as "C-states. Nutanix recommends disabling C-states 3 and To disable these modes automatically, run the following commands from one of the controller VMs: hostssh chkconfig --add cstate hostssh service cstate start 13 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

14 Best practices and recommendations 4.3 VM recommendation The virtual machine recommendations are as follows: Use minimum 4 vdisks to create HANA data volumes and HANA log volumes respectively. Make sure that you have used the supported file system as described in SAP note Use of the Linux Logical Volume Manager (LVM) is fully supported by SAP, as described in SAP note Both HANA data volume and HANA log volume should be using separate LVM volume group with the striping done using all physical volume in that volume group. To create the respective file system, follow these steps: 3. Create log, data, and shared volume groups for SAP HANA: vgcreate hanalog /dev/sd{b,c,d,e} vgcreate hanadata /dev/sd{f,g,h,i} vgcreate hanashared /dev/sdj 4. Create logical volumes for log and data striped across 4 vdisks with 64K stripe size and readahead= none. Use all logical extents of a volume group for the logical volumes: lvcreate -i 4 -I 64K -l <LogicalExtentsNumber> -r none -n vol hanalog lvcreate -i 4 -I 64K -l <LogicalExtentsNumber> -r none -n vol hanadata lvcreate l <LogicalExtentsNumber> -r none -n vol hanashared 5. Create XFS file systems on the log and data volumes mkfs.xfs /dev/mapper/hanalog-vol mkfs.xfs /dev/mapper hanadata-vol mkfs.xfs /dev/mapper hanashared-vol 6. Create mount points /hana/log, /hana/data and /hana/shared mkdir -p /hana/{log,data,shared} 7. When creating the virtual machine, ensure that the following settings are in place: a. VM NUMA affinity can be set by running the following acli command from host CVM, and ensure the VMs are powered off before running this command: acli vm.update <vm name> num_vnuma_nodes=<number of virtual sockets> Example: acli vm.update SAP-HANA num_vnuma_nodes=1 b. Memory allocation to the VMs can be changed either updating VMs from Nutanix Prism or from CVM acli. acli vm.update <vm name> memory=<memory size> 8. Power on the VM on host using: vm.on <vm_name> host=<hypervisor/host IP> 14 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

15 Best practices and recommendations Once NUMA node affinity is set and memory is assigned, the details can be verified by running following command from respective AHV host. ~]# numastat qemu-kvm Example of 2 sockets node with NUMA node affinity set for HANA VM - Per-node process memory usage (in MBs) PID Node 0 Node 1 Total (qemu-kvm) (qemu-kvm) Total Enable the VM metrics host daemon as described in SAP note After installation of SAP HANA max_parallel_io_requests for Data and log can be set by running the following command: su - <sidadm> hdbparam --show hdbparam --paramset fileio.max_parallel_io_requests=256 Up to HANA1SP12, the hdbparam tool was part of the HANA installation and was used to manage a subset of HANA configuration parameters. Starting with SAP HANA 2.0, the hdbparam command-line tool has been deprecated. Instead, the parameters are defined as normal parameters in global.ini. Set the parameter as follows in the global.ini file: max_parallel_io_requests[data]=256 max_parallel_io_requests[log]=256 For more information, see SAP Note : Elimination of hdbparam in HANA SAP HANA sizing considerations With SAP HANA Tailored Datacenter Integration (TDI) phase 5, SAP introduced customer-workload-driven SAP HANA system sizing. With this new sizing, SAP application performance standard (SAPS) requirements for specific customer workloads are used to determine the type and number of processors that are required to run SAP HANA. You can use the SAP HANA Quick Sizer tool and sizing reports and share the results with Dell EMC to determine the optimal number of Dell EMC XC Family nodes, CPU types, and memory sizes for their SAP HANA environment. 4.5 Health check and performance monitoring Health check Dell EMC highly recommends keeping the cluster in a healthy state by regularly performing NCC health check option available from Nutanix PRISM or running the following command from a Host CVM nutanix@ntnx-xxx:~$ ncc health_checks run_all The Health dashboard displays dynamically updated health information about VMs, hosts, and disks in the cluster. 15 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

16 Best practices and recommendations Nutanix Prism Health Dashboard Software update Dell EMC recommends regular updates for AOS, hypervisor, and firmware versions to the latest available Performance monitoring Monitor cluster performance for a wide range of parameters using Nutanix PRISM. The Analysis dashboard lets you create charts that can monitor various performance measures. You can export these charts to any external system, if required. Nutanix Prism Analysis Performance chart 16 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

17 References 5 References See the following referenced or recommended resources that are related to this document: Note: The following links are open to customers although some may require registration for access. 5.1 Dell EMC XC Family 5.2 Nutanix 5.3 SAP HANA Dell.com/XCSeriesmanuals is focused on meeting customer needs with proven services and support. XC Series and XC Core Technical Resource Center on DellEMC.com provides expertise to ensure customer success on Dell EMC XC family Dell EMC XC Series Hyper-Converged Appliances on DellEMC.com provides marketing materials and the latest product information on the XC Family. Dell EMC 14th Generation XC Family: Dell EMC XC Series Networking Deployment and Best Practices guide Nutanix Bible: Nutanix blog: AHV Best Practice Guide: NCC health check: Nutanix Best Practice Guide for SAP HANA: Nutanix HA Guide: Prism-v58:ahv-acropolis-cluster-setting-ha-t.html For details on SAP HANA sizing, see: For SAP HANA Systems based on TDI approach, see the document for hardware sizing: 17 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

18 Appendix A Appendix A.1 SAP HANA cluster set up used for certification The cluster hardware details for the certification process are provided in Table 3. Server Model Dell EMC XC Dell EMC XC740xd-24 Cluster hardware details CPU Intel Xeon Gold GHz Intel Xeon Gold GHz Number of Sockets 4 sockets with 12 cores each 2 sockets with 18 cores each Memory Disk Network 48 DIMMS 64 GB each DDR4 3TB 6 DIMMS 64 GB each DDR4 384 GB 4 * SSD GB 10 * SSD GB 8 * SSD GB Integrated NIC 1: Intel(R) 4P X550-t rndc NIC Slot 3: Intel(R) 10GbE 4P X710 Adapter Ports=4 Integrated NIC 1: MLNX25GbE 2P ConnectX4LX RNDC NIC Slot 7: MLNX25GbE 2P ConnectX4LX Adapter Ports=2 Network B/W Used 10 GbE 10 GbE A.2 Certified configurations Dell EMC supports SAP HANA on XC740xd and XC940 with the following configurations or higher: Certified configurations XC740xd-24, 2U/1 Node Dual socket: Intel Xeon Gold 6126 and higher or Intel Xeon Platinum processors XC940-24, 3U/1 Node Quad socket: Intel Xeon Gold 6126 and above or Intel Xeon Platinum processors 24 DIMM slots; up to 3 TB RAM (1.5 TB per processor) 24 x 2.5 drive slots, all flash SSD only or SSD + NVMe (80 TB max) 48 DIMM slots; up to 6 TB RAM (1.5 TB per processor) 24 x 2.5 drive slots, all flash SSD only or SSD + NVMe (80 TB max) 18 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02

19 Appendix Networking: 2x10, 4x10 or 2x25 GbE Power: Titanium 750W, Platinum 495W, 750W, 1100W, 1600W, and 2000W Networking: 2x10, 4x10 or 2x25 GbE Power: Platinum 1100W, 1600W, 2000W, 2400W, VDC 1100W, Gold 48VDC 1100W 48VDC 1100W, 380HVDC 1100W, 240HVDC 750W 19 SAP HANA on Dell EMC XC Appliances and XC Core Systems Best Practices Guide A02