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Overview
This section describes the best practices that Dell EMC recommends for configuring the Ready Bundle for SAP Landscapes solution.
Server configuration
Dell EMC recommends the following best practices for configuring the PowerEdge servers:
Local area network
Dell EMC recommends the following best practices for configuring the LAN:
Storage area network
Dell EMC recommends the following best practices for designing the storage area network (SAN):
Storage configuration
The Dell EMC Unity array is a virtually provisioned, flash-optimized storage system that is designed for ease of use. This section introduces specific configuration recommendations to enable you to obtain good performance from your Unity array.
The main design principles supporting good performance are:
Flash drives
Dell EMC storage arrays use multiple types of drives with varying capacities and performance levels. The arrays try to match data with the optimal drive type based on storage profiles. Typically, mission-critical data is stored on high-performance drives, while less-critical data is moved to high-capacity drives.
Unity all-flash technology supports high-capacity flash drives that provide very high IOPS per terabyte (IOPS/TB). By taking advantage of the increases in flash memory densities and economies of scale that industry-standard flash-drive technology provides, Unity all-flash technology offers a differentiated capability with respect to many all-flash alternatives.
Storage provisioning
As a fully unified storage system, the Unity array offers both block and file provisioning in the same enclosure. The system provisions disks into storage pools that can host both block and file data and supports connectivity for both block and file protocols. Dell EMC recommends the following best practices:
Unity OE version 4.2 on Unity All Flash models supports dynamic pools. Dynamic storage pools apply RAID to groups of drive extents from drives within the pool and allow for greater flexibility in managing and expanding the pool. Dynamic pools must be all-flash pools and cannot be built with HDDs (SAS and NL-SAS).
Dynamic pools do not require hot spares. A dynamic pool automatically reserves spare space in the pool at a rate of 1 drive’s worth of space for every 32 drives. If a drive failure occurs, the data that was on the failed drive is rebuilt into the spare capacity on the other drives in the pool.
RAID specification
The Unity array applies RAID protection to the drives in a storage pool. Selecting the appropriate RAID type is an important decision for a successful implementation. Consider elements such as performance, capacity, and availability.
Dell EMC storage systems support RAID 1, RAID 5, and RAID 6. Each RAID type provides different performance, capacity, and protection levels, as follows:
Customers select the RAID type and disk type combination based on their requirements. In a Dell EMC FAST™ for Virtual Pools (FAST VP) environment, Dell EMC recommends RAID 5 for flash, RAID 1 for FC, and RAID 6 for SATA. Table 7 shows how RAID levels compare in random read, random write, sequential read, and sequential write scenarios.
Table 7. Comparison of RAID levels
RAID level | Random read | Random write | Sequential read | Sequential write |
RAID 1 | Excellent | Excellent | Excellent | Excellent |
RAID 5 | Excellent | Good | Good | Moderate |
RAID 6 | Good | Poor | Good | Moderate |
Unity global memory
Global memory is a crucial component in the Ready Bundle for SAP Landscapes solution architecture. All read and write operations are transferred to or from global memory. The processing of transfers between the host processor and SPs occurs at much greater speeds than transfers involving physical drives. Unity OE uses complex, intelligent, statistical pre-fetch algorithms, which adjust to workload on the array by constantly monitoring, evaluating, and optimizing cache decisions.
Unity All Flash systems share a number of similarities in form factor and connectivity but scale in processing and memory capabilities from 48 GB per SP to 256 GB per SP.
Front-end connectivity
The Unity array provides multiple options for front-end connectivity through on-board ports directly on the disk processor enclosure (DPE) and through optional I/O modules. In general, Dell EMC recommends that you:
For example, when configuring the four-port FC I/O module, zone different hosts to different ports so that all eight ports across the two SPs are used. Do not simply zone all hosts to the first port of each I/O module.
Fibre Channel
For FC, configure Dell EMC Unity CNA ports and I/O module ports with 8 Gb or 16 Gb small form-factor pluggable (SFP) transceivers. All FC ports can negotiate to lower speeds. Dell EMC recommends 16 Gb FC for the best performance.
Dell EMC recommends that you use single-initiator zoning when creating zone sets. For HA purposes, zone a single host initiator to at least one port from SP A and one port from SP B. For load balancing on a single SP, zone the host initiator to two ports from SP A and two ports from SP B. When zoning additional host initiators, where possible, zone them to different SP ports to spread the load across all available SP ports.
On hosts connected with FC, use multipathing software such as the Dell EMC PowerPathTM solution. The PowerPath software coordinates with the Unity system to provide path redundancy and load balancing.
Setting I/O paths
FC zoning partitions the FC fabric into multiple subsets. A zone includes FC initiators and targets and enables communication between them. Consider the following when setting the I/O paths:
Volume provisioning and mapping
Thin provisioning enables you to increase capacity utilization by presenting more storage to a host than is physically consumed and by allocating storage only as needed from a shared virtual pool.
To obtain optimal performance, Dell EMC recommends the following best practices for creating thin LUNs:
After creating the LUNs, create a server cluster for HA and map the volumes to the server cluster. Related initiators (HBAs) are grouped by host, while related devices are grouped by storage pool.
NAS servers
NAS servers host file systems on the Unity storage system. NAS servers use virtual interfaces to enable host connectivity to SMB, NFS, and multiprotocol file systems, as well as VMware NFS datastores and VVols. Depending on what is enabled on the NAS server, you can create SMB file systems and NFS file systems separately or in a multiprotocol configuration. File systems and virtual interfaces are isolated to a single NAS server, allowing for multitenancy over multiple NAS servers. NAS servers are hosted on an SP and automatically fail over if the SP becomes faulted. Any associated file systems also fail over.
Unity file systems
File systems are file-based storage resources that are hosted on NAS servers. They are accessed through shares, which can be provisioned for SMB or NFS access, providing access for Windows or UNIX hosts. Depending on what protocol is selected for your file system, only shares of that type can be provisioned. For example, for an SMB file system, you can provision SMB shares, but not NFS shares. To provision both SMB and NFS shares from a file system, use a multiprotocol file system.
File systems can be extended and shrunk in size, and allocated space is automatically taken and reclaimed based on file system usage patterns. Finally, file systems can be configured with quotas to better regulate file system space usage. Tree quotas and user quotas are supported on file systems and can be used in combination.
The distributed architecture of SAP NetWeaver systems requires that global file systems are physically shared from the ABAP SAP Central Services (ASCS) instance to all SAP NetWeaver Application Servers (AS) belonging to the same SAP system using the NFS protocol. Examples include:
Two methods are used to physically share these global file systems: server-based NFS and storage-based NFS. Unity file systems can provide storage-based NFS to satisfy the SAP global file system requirements.
Unity compression
To help reduce the total cost of ownership (TCO) and increase the efficiency of a Unity storage system, Dell EMC added compression in Unity OE version 4.1, with initial support for ”thin block” storage resources. Unity OE version 4.2 and later versions include support for ”thin clones” and ”thin file” storage resources.
With compression, a smaller amount of space is required to store a dataset for compression-enabled storage resources. This space savings reduces the amount of physical storage that is required to store a dataset, which can yield cost savings. Space savings are also realized on the storage resources.
Snapshots and thin clones
Snapshots and thin clones inherit the compression setting of the source storage resource, which helps increase the space savings that they can provide.
Competing workloads
When adding workloads to the Unity system, consider the reported CPU utilization rates as well as the capacity and IOPS sizing. Brief spikes of high utilization are normal and expected on any Unity system.
In highly consolidated environments, databases and applications compete for storage resources. The Host I/O Limits quality of service (QoS) feature controls “noisy neighbors” and protects the performance of the production system. You can apply host I/O limits on LUNs, VMware vStorage, VMware NFS datastores, and their associated snapshots to limit the number of IOPS serviced by the Unity system.
Use host I/O limits to limit incoming host activity on the basis of IOPS, bandwidth, or both. You can enforce limits on individual resources, or you can share a limit among a set of resources.
Host I/O limits can be effective if an overload on the storage resources affects the performance of critical applications such as SAP production installations. Consider configuring host I/O limits on LUNs, datastores of non-SAP applications, or SAP nonproduction systems to limit the total IOPs or bandwidth, which might otherwise consume a large portion of the system’s resources and affect the performance of SAP production systems.
Data Domain configuration
Dell EMC recommends the following best practices for configuring your Data Domain system:
Running SAP on VMware
Dell EMC recommends that you adhere to the following VMware sizing rules and considerations when you run your SAP system on VMware.
Note: If an ESXi host fails, vSphere HA powers on the SAP VMs according to the VM restart priority. ASCS has the highest priority followed by the database, followed in turn by the application servers.
To enable VMCP, check the Protect against Storage Connectivity Loss option. Then, in the Failure conditions and VM response list box under the vSphere HA Cluster setting, select Power off and restart VMs for:
For more information, see SAP on VMware Best Practices.
Figure 4 shows our storage design layout for VMware VMs.
Figure 4. Storage design layout for VMware VMs
SAP system architecture
Because SAP ERP is one of the most important transactional systems in a typical enterprise IT environment, the system architecture must consider both performance and availability. Dell EMC highly recommends a distributed system architecture, where each of the main components resides on its own VM, as follows: