Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX

Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A Dell Reference Architecture for 2,000 users with mailbox resiliency. Dell Global Solutions Engineering June 2013

Revision History Date June 2013 Description Initial release 2013 Dell Inc. All Rights Reserved. Dell TM, the Dell logo, PowerEdge TM and other Dell names and marks are trademarks of Dell Inc. in the US and worldwide. Intel and Xeon are registered trademarks of Intel Corporation in the U.S. and other countries. Microsoft, Windows, Exchange, Hyper-V and Windows Server are either trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. All other trademarks mentioned herein are the property of their respective owners. 2 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

Table of Contents Revision History... 2 1 Introduction... 4 1.1 Objective... 5 1.2 Audience... 5 2 Solution Components... 6 2.1 Overview of Dell PowerEdge VRTX... 6 2.2 Overview of Microsoft Hyper-V Reference Architecture with VRTX... 7 2.2.1 Overview of storage architecture and configuration... 9 2.2.2 Overview of Network Architecture and Configuration... 10 2.3 Microsoft Exchange Server 2013... 11 3 Exchange 2013 Reference Architecture Details... 12 3.1 Exchange Virtual Machines... 13 3.1.1 Exchange Virtual Machines Configuration... 13 3.2 Windows Server 2012 Hyper-V Cluster... 14 3.3 Windows Server 2012 Hyper-V Host Configuration... 14 3.4 Storage Configuration... 15 3.5 Exchange Networking Configuration... 16 3.6 Failure and Recovery Scenarios... 17 4 Configuration Details... 19 4.1 Solution requirements... 19 4.2 Recommended solution... 20 A Additional Resources... 22 3 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

1 Introduction Traditional Information Technology (IT) Infrastructures suffer from complexities due to disparate hardware, proliferation of various system management tools, and hardware sprawl. Such inefficient infrastructures can lead to increased Total Cost of Ownership (TCO), system downtime for maintenance, and inflexibility in handling performance demands. Downtime and poor performance in turn impact the application endusers and can adversely impact the entire organization when a business-critical application such as email is involved. Dell PowerEdge VRTX reduces complexity, downtime, and performance issues by: Combining servers, storage, and networking into easy-to-deploy chassis. Providing unified and simplified systems management. Ensuring more service uptime with application high availability. Engineers at Dell Global Solutions Engineering group have developed and validated a novel design for virtualized workloads, consisting of Dell PowerEdge VRTX with Microsoft Hyper-V. The proposed reference implementation utilizes the advanced features of VRTX in combination with the salient features of Microsoft Server 2012 with Hyper-V. This reference implementation is pre-engineered, validated, and ready to be leveraged for deploying enterprise messaging applications. The study in this guide describes reference architecture for Microsoft Exchange Server 2013 that takes advantage of the pre-engineered PowerEdge VRTX with Hyper-V reference implementation. This reference implementation has been used as the underlying platform for Microsoft Exchange Server 2013 to build a virtualized, highly available and site-resilient messaging solution. The Microsoft Exchange solution uses only a portion of the VRTX system, leaving ample resources for running additional applications. The reference architecture uses two VRTX systems for a two site configuration with one VRTX chassis in each site. Use of Exchange Database Availability Groups (DAG) provides high availability for Exchange databases across the two sites. Administrators do not have to worry about a site failure, because each site is configured to provide site resiliency for the other. Resiliency is provided at multiple levels: The architectural design ensures inter-site resiliency. In case the VRTX system in one of the sites experiences an outage, the VRTX system at the other site keeps the email service up for the users while the failed VRTX system is being recovered. The design also takes into consideration intra-site resiliency. The VRTX system itself is intelligently designed to provide resiliency in case of any component failure within the system. In the event of a host server failure, Hyper-V High Availability restarts the Exchange VMs from the failed server on other available hosts as part of the cluster. Once the Exchange VMs boot up and the Exchange services are restarted, the DAG gets re-established. Use of Hyper-V failover clustering with Cluster Shared Volumes (CSV) enables complete mobility for the Exchange virtual machines within the cluster. This helps to keep the service running during scheduled maintenance by migrating over the Virtual Machines (VM) to another host. 4 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

This guide describes the solution in a structured way. Section 2 describes the key components used in the solution reference architecture. These components are selected and engineered to make the solution as complete and effective as possible. Understanding these elements is essential for comprehending the reference architecture. Section 3 describes the actual Hyper-V and Exchange Server 2013 solution design. Section 4 provides the configuration details to deploy the solution. For the purpose of this guide, the terms Branch Office and Site are used interchangeably. 1.1 Objective The study provides reference architecture for highly available messaging solution with site resiliency for Exchange 2013 Server that is built on top of Dell s pre-engineered and validated PowerEdge VRTX with Microsoft Hyper-V reference implementation. The reference architecture consists of a multi-site configuration for up to 2,000 mailboxes. The design leverages Microsoft Hyper-V clustering technology with CSV for messaging availability within a site and uses Microsoft Exchange Server 2013 DAG technology for cross-site resiliency. The combination of these two high availability methodologies greatly reduces down time and improves quality of service. The PowerEdge VRTX is used as a shared infrastructure with Microsoft Exchange using a portion of the total resources and allowing the rest of the resources to be used with other applications. 1.2 Audience This guide is intended for IT professionals and administrators interested in designing and deploying a custom-sized Microsoft Exchange 2013 solution up to 2,000 mailboxes, on Dell PowerEdge VRTX with Hyper-V. While the guide provides an overview of the Dell PowerEdge VRTX and Exchange Server, the reader is expected to have a sufficient understanding of Microsoft Hyper-V and Microsoft Exchange Server 2013. 5 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

2 Solution Components This reference architecture is based on Dell PowerEdge VRTX and incorporates Windows Server 2012 with Hyper-V and Microsoft Exchange 2013 Server. 2.1 Overview of Dell PowerEdge VRTX Dell PowerEdge VRTX combines server, storage, and networking into a single all-encompassing chassis. The design of the new VRTX platform was inspired by the need to specifically address and resolve IT concerns in office environments. Many of the IT pain points experienced in branch office environments are the same as those of data centers, e.g. having insufficient performance to process jobs or transactions quickly, inflexibility to grow over time with minimal disruption, and ensuring that systems, applications and data are highly available. Office environments range across single, stand-alone offices to multiple distributed offices of large enterprises and public organizations. With a wide array of customer-inspired features and capabilities, VRTX offers optimized dimensions, security, acoustics, and power options that are a very compelling value proposition. The simple, integrated, and scalable shared storage in VRTX addresses the requirements of virtualized workloads and projected storage capacity and performance. Figure 1 Dell PowerEdge VRTX logical representation VRTX is a shared infrastructure platform which uses industry-standard PCIe IO cards with shared storage providing a massive amount of local storage within the chassis (up to 48TB in the 3.5 HDD bay chassis). 6 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

The storage is shared amongst four server nodes and is managed through the VRTX Chassis Management Controller (CMC). The virtual disks can be created and assigned to single or multiple server nodes (multiple if clustering-aware software is installed). Using the CMC, the PCIe slots can be flexibly assigned to server nodes. Up to four PCIe slots can be assigned to a single server node. The assignments are flexible during initial setup such that any PCIe slot may be assigned and mapped to any server node. These mappings can be reassigned at a later stage, provided the servers involved are power cycled. Table 1 Feature VRTX High Level Feature List Description Server Compatibility Form Factor Dell PowerEdge M520/M620 servers Standalone Tower or 5U Rack enclosure No. of Servers Up to 4 I/O Power Supplies Chassis Storage 8 PCIe slots (supporting Ethernet, FC, GPU) Up to 4 PSUs (PSU & AC redundant options) Up to 12 3.5 NLSAS, SAS HDDs/SSDs or Up to 25 2.5 NLSAS, SAS HDDs/SSDs Raid Controller Shared Power Edge Raid Controller (PERC 8) Management Network 1 or 2 Chassis Management Controllers 1GbE pass-through module or 1GbE internal switch module (8 external ports) For more information on Dell PowerEdge VRTX, refer PowerEdge VRTX shared infrastructure platform. 2.2 Overview of Microsoft Hyper-V Reference Architecture with VRTX Windows Server 2012 Hyper-V increases operational efficiency by enabling server virtualization to make optimum use of server hardware. With Windows 2012, Microsoft has introduced a significant number of improvements that allow customers to take advantage of new server, storage, and network hardware technologies. The goal of this architecture is to provide an efficient branch office infrastructure solution that reduces the management and support overhead, while keeping in place the virtualized and shared infrastructure best practices that benefit enterprise class messaging applications. The VRTX reference architecture also intends to provide comprehensive design information on the core infrastructure services that are based on Windows Server 2012. 7 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

Figure 2 PowerEdge VRTX Hyper-V Cluster Reference Architecture The key benefits of the VRTX with Hyper-V reference architecture to Exchange Server 2013 solution include: Efficient application management and best practices achieved through hardware abstraction at various levels of the infrastructure, such as storage, network, and server. Centralized management of the application ecosystem. Complemented high availability for the application servers. Reduction in the Total Cost of Ownership. The branch office solution includes PowerEdge M620 servers running on Dell PowerEdge VRTX chassis, hosting a virtualization solution based on Microsoft (Hyper-V), with Dell Networking 5524 network 8 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

switches as the network backbone and PowerEdge VRTX internal shared storage as the Storage Area Network (SAN). Table 2 lists the compute resources used in the VRTX reference architecture. Table 2 Resource Compute Nodes Processors Compute Resources for PowerEdge VRTX with Hyper-V Reference Architecture Description Up to 4 x PowerEdge M620 or M520 server nodes Up to 2 x Intel E5-2600 Family in each M620 Up to 2 x Intel E5-2400 Family in each M520 Up to 768GB (with 32GB LRDIMMS) in each M620 Memory Up to 384GB in each M520 The following sections describe the features of the Hyper-V reference architecture with VRTX that can benefit an enterprise-class messaging application. 2.2.1 Overview of storage architecture and configuration The Hyper-V cluster in this reference architecture utilizes the storage virtual disk (VD) option. The reference architecture design requires a minimum of three VDs for the cluster Quorum configuration, the CSV to host the management infrastructure VM Virtual Hard Disk (VHDs), and the CSV for compute or workload VM VHDs. As per the design, dedicated storage drives are used for the Management VDs and the Workload VDs. All the virtual disks are given read-write access to all four physical nodes in the VRTX chassis to enable failover clustering as well as live migration. There is one dedicated global hot spare disk configured to handle physical hard drive failure in the shared storage of the VRTX chassis. The VRTX chassis offers two options for disk configurations: 12 x 3.5 inch spindles and 25 x 2.5 inch spindles. The study described in this paper uses 2.5 inch disks. If you use the PowerEdge VRTX chassis with 2.5inch disks, the cluster Quorum and the Management infrastructure CSV is configured on the first four disks with RAID 10 along with the respective settings as shown in Figure 3. Figure 3 Virtual disk configuration on 2.5 PowerEdge VRTX chassis 9 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

As shown in Figure 3, twenty-one spindles are available for storing workload-related data like email databases, guest OS images of workload VMs, etc. It is recommended to reserve at least one disk as a global hot spare. However, to achieve appropriate isolation between the VM guest data store and the application specific data, the available physical disks must be grouped appropriately as VDs. 2.2.2 Overview of Network Architecture and Configuration The Dell PowerEdge VRTX chassis offers two options for the network fabric, a pass-through module and an Ethernet switch module. To reduce the cost and build high availability, redundant network architecture is designed by mapping the host ports to redundant Dell Networking 5524 top of rack (ToR) switches to support management, live migration, and cluster interconnect traffic. The traffic types are logically separated through the use of VLANs and quality of service (QoS) settings. The two switches are lagged together through an inter-switch-link (ISL), which provides a 20 Gb bandwidth between the two switches. The solution provides four 1 Gb uplinks from each switch to link into an existing core network infrastructure. Each Dell PowerEdge M620 server node is configured with a Broadcom BCM57810 network daughter card (NDC) providing two 1 GbE ports, as the Network Fabric A bandwidth supports only 1 Gb network. Another PCIe Network Broadcom BCM 5720 Dual Port adapter is configured to provide additional bandwidth and high availability for the Hyper-V cluster. All four network ports, two ports from the Network pass-through switch and two from the PCIe adapter, are connected to the redundant Dell Networking 5524 switches placed outside of the PowerEdge VRTX enclosure. Figure 4 Logical network architecture for PowerEdge VRTX 10 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

On the Microsoft Hyper-V host, a converged network design using Microsoft NIC teaming is used to provide network connectivity to the application virtual machines, as shown in Figure 4. For more details on the configuration of this converged network design, refer to the Reference Architecture on Dell PowerEdge VRTX using Microsoft Hyper-V 2012. 2.3 Microsoft Exchange Server 2013 Microsoft Exchange Server 2013 provides significant value and incentive over previous versions. There have been improvements in several areas ranging from application performance to everything you need to deploy and manage an email solution. Most of the enhancements have been in the areas of architecture, storage, and high availability (HA) and site resiliency, compliance and ediscovery, Lync 2013 integration, and Outlook Web Access (OWA). The newer architecture reduces the number of server roles from four in Exchange 2010 to two in Exchange 2013: Client Access Server and Mailbox Server role. The Exchange 2013 Mailbox server role includes all the server components for Exchange (Transport service, Client Access protocols, Mailbox databases, and Unified Messaging.) The Client Access in Exchange 2013 has been reduced to a light weight and stateless process which provides authentication and proxy service offerings, HTTP, POP, IMAP and SMTP client access protocols. The Exchange 2013 new architecture enables the following key advantages: Ease of deployment Reduced number of lightly coupled server roles Client Access Server and Mailbox Server roles. Support for large disks Up to 8 TB with reduction in IOPS. Optimized usage of disks Enabled through capability to host multiple databases on a single storage volume. Easy administration Exchange deployment can be easily administered using the all new webbased Exchange Administrative Center (EAC). Consolidating the Client Access Server role and the Mailbox Server role on a single server, results in a multi-role Exchange server configuration. There are a number of benefits to considering a multi-role server configuration in a virtualized and shared infrastructure, such as: Lower capital expenditure and operational expenditure. Simplicity in deployment. Less number of virtual servers to be administered and scheduled in the virtual cluster. With its architectural modifications, Microsoft presents Exchange Server 2013 as an improved enterpriseclass email software solution. 11 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

3 Exchange 2013 Reference Architecture Details This section describes the design points and explains how the different software and hardware components (Hyper-V, Exchange Server 2013, and VRTX) within the solution enable these design points to fulfill the high availability and performance requirements. The Exchange Server 2013 reference architecture presented here uses the VRTX based on the 2.5 inch drive chassis. The drive type used for the storage configuration is 1.2 TB SAS 10K disks. This reference architecture uses 12 of these disks for storing Exchange Server 2013 databases and logs. The Exchange Server 2013 DAG is utilized with one database copy per VRTX enclosure. Each VRTX system will host two different DAGs. The shared storage uses the 2.5 SAS 10K drives with 1.2 TB raw capacity. Twelve disks are utilized for the Exchange Server database and logs, 6 for each DAG. Figure 5 provides a high level logical diagram for server and storage design for each VRTX in each site used in this reference architecture. Figure 5 Reference Architecture Logical Diagram 12 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

This reference architecture design incorporates Hyper-V host clustering in conjunction with Exchange 2013 DAG. Hyper-V clustering is used as the first line of defense against software or hardware faults within a single VRTX. As the second line of defense against complete VRTX outage, two Exchange 2013 DAGs are used. These two DAGs are established between two pairs of Exchange 2013 virtual machines each. Each pair in a DAG spans Site 1 and Site 2. For software or hardware faults within a VRTX, Hyper-V clustering is used to restart the Exchange 2013 mailbox virtual machine on another available clustered Hyper-V host within the same VRTX. During this failover, it is recommended that the passive copy on the other site does not get activated. The administrator should block the remote mailbox server explicitly to avoid activating database copies automatically by using the command-let Set-MailboxServer. In case of total VRTX outage, Exchange 2013 DAG functionality enables the restoration of mailbox services to users affected by VRTX outage, by activating the passive copy on the secondary site. This design helps maximize mailbox service availability and site resiliency for mailboxes. The VRTX platform is envisioned to be a shared infrastructure hosting multiple workloads aside from Exchange 2013. One of the design points in sizing this reference architecture is a balanced use of resources to allow for multiple workload scenarios. The Exchange VMs are configured as part of the four node cluster. For storage capacity and performance, 12 out of the total 25 disks within each VRTX enclosure are dedicated to Exchange 2013 mailbox store. The target for the number of mailboxes for the overall solution is 2,000. Each mailbox is sized for 1.5 GB of capacity. The profile for each mailbox user is projected to be 150 messages sent and received per day. The 2,000 mailboxes span the Branch Office 1 and Branch Office 2, with 1,000 mailboxes served by each branch office. With the Microsoft Exchange 2013 DAG design, Branch Office 1 stores and maintains its own active database copy for 1,000 local mailbox users, as well as a passive database copy from its DAG partner at Branch Office 2 and vice versa. 3.1 Exchange Virtual Machines The solution uses Mailbox role and Client Access role combined into one virtual machine. Two virtual machines are created per DAG spanning between both the branch office sites. The DAG virtual machines are configured through the failover cluster manager. 3.1.1 Exchange Virtual Machines Configuration With the architectural changes in Exchange 2013 server roles, Microsoft guidance for virtualizing Exchange 2013 roles has evolved. Refer to the latest guidance on virtualizing Exchange server here. The main considerations for sizing Exchange 2013 virtual machines is virtual CPU to logical CPU ratio and memory requirements, as well as storage space requirements for the guest operating system for paging. The recommended virtual CPU to logical CPU ratio for Exchange 2013 roles is 1:1. Through the use of the PowerEdge M620 server nodes, the PowerEdge VRTX system offers Intel Xeon E5-2600 series of processors. This series can go up to eight cores per socket, thus the customer now has a total of sixteen cores per server host, and maintaining a one vcpu to one core ratio can easily support the two Exchange VMs as part of separate DAGs on the same host. Table 3 details the virtual machine requirements for each of the four Exchange 2013 virtual machines part of the reference architecture. 13 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

Table 3 Reference Architecture Exchange 2013 VM requirements Component Requirement Operating System Windows Server 2012 Virtual CPUs 6 Memory (RAM) Virtual NIC 48 GB 2 (one for private network and one for public Exchange 2013 network) 3.2 Windows Server 2012 Hyper-V Cluster The PowerEdge M620 servers run Window Server 2012 with Hyper-V role installed and are part of one cluster. The cluster hosts both the Exchange 2013 virtual machines and the management virtual machines required for deploying and configuring Exchange 2013 setup. For more information on the network, storage, and management VMs design for the Hyper-V VRTX architecture solution, refer to the Reference Architecture on Dell PowerEdge VRTX using Microsoft Hyper- V 2012. 3.3 Windows Server 2012 Hyper-V Host Configuration Each Microsoft Hyper-V node hosting Exchange 2013 virtual machines should provide a minimum of 14 CPU cores, six for each Exchange 2013 virtual machine and additional CPU cores for the underlying Hyper-V host. A minimum of 48 GB RAM should be dedicated to each Exchange 2013 virtual machine. This means that each Hyper-V host should have at least 96 GB RAM dedicated to Exchange 2013 virtual machines. Microsoft recommends against oversubscribing CPU and memory resources on workloads such as Exchange 2013 where the virtual machine memory and CPU resources are needed on an ongoing basis. Table 4 Reference Architecture Microsoft Hyper-V host requirements Component Requirement Operating System Windows Server 2012 CPU Memory (RAM) Minimum 2 sockets with 8 CPU cores per socket 128 GB (recommended) NIC 2 14 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

3.4 Storage Configuration The storage configuration for this reference architecture is based on the storage options as described in section 2.2.1. The Exchange solution utilizes twelve, 1.2 TB SAS 10K 2.5 inch drives available from the VRTX infrastructure leaving the remaining storage capacity (eight drives) to be used by other application VMs of the branch office. A single volume of RAID 10 is carved out of the 12 disks and is used to host the Exchange databases for the two DAGs. The volume is presented to all the four Hyper-V cluster nodes, initialized with GUID Partition Table (GPT) and the NTFS allocation unit of 64KB and mounted on each node. The Exchange volume is then added as a CSV disk using the Failover Cluster Manager. Figure 6 VRTX Setup Showing Workload VDs and Disk Configuration for Exchange In order to host the Exchange databases, four VHDX disks are created per DAG, among total eight VHDX disks, and hosted on the Exchange CSV volume. One VHDX disk is dedicated as a restore LUN. These VHDX disks are then mapped to the two Exchange 2013 VMs and mounted to host the active/passive databases. 15 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

3.5 Exchange Networking Configuration On the Hyper-V cluster nodes, the four network ports on the host are teamed in Switch Independent mode and a virtual switch is created on top of the team. Virtual network adapters for the management host OS for the Cluster private, live migration, and in-band management networks are created with and assigned different VLAN IDs and bandwidth weights. For more details on the Hyper-V networking architecture with VTRX, please refer to Reference Architecture on Dell PowerEdge VRTX using Microsoft Hyper-V 2012 documentation. Figure 7 Exchange application networks for single host The Exchange solution uses private and public networks for Messaging API (MAPI) and replication respectively. Two virtual NICs are created for these networks and assigned respective VLAN IDs. Consistent network configuration is applied across all the DAG virtual machines. The server side ports on the Dell Networking 5524 switch are tagged appropriately with the Exchange network VLAN IDs and the Hyper-V network VLAN IDs. 16 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

Exchange 2013 virtual machines configured as DAG partners depend on Hyper-V host network connectivity between branch offices. Microsoft cluster server role is enabled on each Exchange 2013 virtual machine with the two standard networks. The public (MAPI) network is configured for client connectivity, and the private network is configured for cluster heartbeat and log replication. These networks are configured for redundancy such that the public and private networks stay up and remain functioning in the event of a single NIC failure. Figure 8 Exchange application networks across sites 3.6 Failure and Recovery Scenarios The failure scenarios addressed by this design cover some of the typical issues faced by IT when working with Exchange Server 2013. The two DAG design was chosen due to the requirement of both sites having active mailboxes and preventing local mailbox user s interruption due to a network failure between sites. 1. Intra-Site Hyper-V host failure: In case of a Hyper-V host failure, the Hyper-V Failover Clustering will automatically retarget virtual machines to the remaining hosts within the same VRTX unit. In this case the Exchange Server virtual machine will be restarted on a different Hyper-V host but the Exchange Server DAG will indicate a momentary loss of communication. All active databases will remain hosted on the same virtual machine. To avoid any unwanted mailbox database activation in the remote site, it is necessary to set the DatabaseCopyAutoActivationPolicy property to be blocked using the Set- MailboxServer cmdlet. 17 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

2. Inter-Site Network Communication failure: In case the network channel between the sites is unavailable and both VRTX units are fully operational, users will continue accessing mailboxes normally at each site. The DAG will maintain quorum at each site since each witness server is local to the active mailbox server VM. When communication is restored between the sites, database replication will be resumed and the remote database copy will replay transaction logs to synchronize content. Use Set-DatabaseAvailabilityGroup WitnessServer AlternateWitnessServer for each DAG to correctly set the witness server and alternate witness server. The witness server for DAG1 is the mailbox server belonging to DAG2 in the same site as the active copies for DAG1.The alternate witness server for DAG1 will be the mailbox server belonging to DAG2 in the remote site. The same concept applies to DAG2 witness placement. Refer to figure 8 for VM naming and placement. Refer Table 5 for the summary of these configurations. Table 5 Inter-site DAG and witness configuration summary DAG Active mailboxes Mailbox servers Witness server Alternate witness server DAG1 Site 1 VM1/VM2 (VM2: block auto activation of DBs) VM3 VM4 DAG2 Site 2 VM4/VM3 (VM3: block auto Activation of DBs) VM2 VM1 3. Full site unavailable: In case one of the site s VRTX is lost, IT will have to manually activate mailbox database copies in the remote location. Activation of the remote Mailbox server in case of full site loss can be done via Stop-DatabaseAvailabilityGroup and Restore-DatabaseAvailabilityGroup commands that enable the remaining node to form a cluster and activate the databases. With a full branch office failure, the Exchange VM hosting passive database copies will not be able to form quorum right away. It is recommended to use DatacenterActivationMode to DagOnly, so the process to restore mailbox services to users in the remote site, assuming users have an alternate way to connect to the remote site, will be straight forward. The Stop-DatabaseAvailabilityGroup cmdlet is used to remove failed servers from DAG membership, and Restore-DatabaseAvailabilityGroup is used to bring the DAG back online by recreating the cluster with the remaining available servers. In the two-dag scenario, only the DAG without contact with the witness server will be offline. Set-DatabaseAvailabilityGroup DatacenterActivationMode DagOnly (performed at DAG creation) Stop-DatabaseAvailabilityGroup identity <DAGName> - MailboxServer <Failed Mailbox Server> Restore-DatabaseAvailabilityGroup identity <DAGName> (performed after Stop- DatabaseAvailabilityGroup command) 4. Database level failure: In case of a database level failure, where only the database is affected, IT has the option to manually activate remote database copies. This scenario assumes that every other component is operational and the affected users hosted in the database activated remotely can access the remote site. This is necessary because DatabaseAutoActivationCopyPolicy is set to Blocked for remote mailbox server VM. However, administrators still can perform manual database activation using the Move-ActiveMailboxDatabase command-let. In this event of losing the active database and failover to passive database, it is expected to have the passive database lagging behind, which has potential impact on the Recovery Point Objective (RPO). 18 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

4 Configuration Details This section prescribes key configurations to accomplish the solution architecture. The solution architecture proposed in this guide incorporates the best-practices for an Exchange Server 2013 deployment within the scope of VRTX hardware features and the underlying Hyper-V virtualization stack. The solution maps the design goals to the set of specific hardware and software resources. These design goals are as follows: Multi-site mailbox resilience. Server and application failure tolerance. Target mailbox size 1.5 GB. Target number of mailboxes 2000. Target message profile per user of 150 messages sent and received per day. The design points emphasize the use of the latest hardware and software features presented in VRTX to achieve mailbox resilience across sites for up to 2,000 users (1,000 users per site). For Exchange Server 2013 mailbox resiliency scenario, a 2-copy DAG across sites is used to provide database level resilience. Also a multiple DAG approach is chosen in order to provide the greatest flexibility and service availability. The number of mailbox users per database is set to allow a smaller failure domain and reduced cross site communication traffic (if remote database activation is performed). 4.1 Solution requirements This section summarizes the solution requirements including sample user and mailbox profiles. These requirements are suitably considered to fit a small or medium sized customer environment. Table 6 Solution requirements Number of Mailboxes Average User I/O Profile (messages per day) Average Mailbox size Limit Total Active/Passive Copies per mailbox database Not included in this solution 2000 150 Messages per day Up to 1.5 GB 2 Backup Infrastructure, Additional servers for CAS/UM 19 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

4.2 Recommended solution This section describes the key solution points that cover the server and storage configurations targeting the solution requirements described in the previous section. Table 7 Recommended server configuration Server/ Storage Configuration Virtualization server(s) Consolidated CAS/Mailbox server virtual machine(vm) Detail Two PowerEdge VRTX with 2.5 disk chassis configured as per reference architecture Reference Architecture on Dell PowerEdge VRTX using Microsoft Hyper-V 2012 following is the recommended server configuration Branch Office 1: 4 x PowerEdge M620 host servers 2 x Intel Xeon processor E5-2600 series [8 cores] and 128GB RAM per server Branch Office2: 4 x PowerEdge M620 host servers 2 x Intel Xeon processor E5-2600 series [8 cores] and 128GB RAM per server Mailbox server virtual machine configured across the following two virtualized PowerEdge VRTX configurations: Branch Office1: 2 CAS/Mailbox VM total; Recommended initial placement 1 per Hyper-V host 6 vcpu with 48 GB virtual memory per VM Branch Office2: 2 CAS/Mailbox VM total; Recommended initial placement 1 per Hyper-V host 6 vcpu with 48 GB virtual memory per VM Number of Database Availability Groups (DAGs) Number of VMs per DAG Number of active and passive mailboxes per mailbox server VM 2 2 Branch Office1: 1000 active per VM, 1000 passive per VM Branch Office2: 1000 active per VM, 1000 passive per VM 20 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

Table 8 Recommended storage configuration per Branch Office Server Configuration Storage Hardware Total Data Volumes Data Volumes per VM Details VRTX shared storage 12 x 2.5 SAS 10K drives at 1.2TB each for Exchange server. Configured in RAID 10. 9 VHDX configured on Cluster Share Volume (CSV) 8 VHDX configured for exchange data; 1 VHDX as restore LUN Each VHDX = 700GB of size. 4 VHDX Databases per volume (VHDX) 1 Mailboxes per database 250 Disk type 2.5 SAS 10K drives of 1.2 TB RAID type RAID 10 Additional details RAID Stripe Size = 256KB or above Read cache policy: Adaptive Read Ahead Write cache policy: Write Back Databases and logs on same container NTFS allocation unit size = 64 KB Redundant switch configuration; Private and Public networks configured as VLANs. 21 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01

A Additional Resources 1. Support.dell.com is focused on meeting customer requirements with proven services. 2. DellTechCenter.com is an IT Community where you can connect with Dell Customers and Dell employees for the purpose of sharing knowledge, best practices, and information about Dell products and installations. 3. Referenced or recommended Dell publications: Dell PowerEdge VRTX Shared Infrastructure Platform Wiki Dell PowerEdge VRTX manuals Dell PowerEdge family manuals Manuals for Dell Chassis Management Controller for PowerEdge VRTX, Dell idrac, and Dell Lifecycle Controller Dell Networking 5524 manuals 4. Referenced or recommended Microsoft publications: http://technet.microsoft.com/en-us/library/jj619301(v=exchg.150).aspx http://technet.microsoft.com/library/dd979799(v=exchg.150) http://technet.microsoft.com/library/dd638137(v=exchg.150) http://technet.microsoft.com/en-us/exchange/fp179701 22 Reference Architecture Microsoft Exchange Server 2013 Virtualized Solution with Dell PowerEdge VRTX A01