advisor and representative deployments...figure 5: question 5 ‐ percentage users in cached mode...

April 2007

Dell Exchange 2007 Advisor and

Representative Deployments

Product Group - Enterprise

Dell White Paper

By Farrukh Noman

Bharath Vasudevan

April 2007 Dell Product Group - Enterprise

Contents

Executive Summary ................................................................................................. 3 Introduction.................................................................................................................. 4 Dell Exchange 2007 Advisor ............................................................................... 5

Addressing Business Needs ............................................................................................ 5

Price versus Performance................................................................................................ 6

Number of Mailboxes ..................................................................................................... 7

Mailbox Size ................................................................................................................... 8

Cached Mode .................................................................................................................. 9

Data Availability........................................................................................................... 10

High Availability .......................................................................................................... 11

Hard Drive Speeds ........................................................................................................ 12

Storage Topology.......................................................................................................... 13

Tape Backup ................................................................................................................. 15

Anti-Virus / Anti Spam................................................................................................. 16

Additional Exchange Server Roles ............................................................................... 17

Exchange 2007 Reference Architecture .................................................... 18 Small Exchange Deployment – Up to 500 Users ......................................................... 18

Exchange Server Layout Recommendations: .............................................................19 Storage recommendations:........................................................................................20 Backup and Availability Recommendations:..............................................................21

Medium Exchange Deployment – Up to 1000 Users ................................................... 22


Large Exchange Deployment - Up to 5000 Users ........................................................ 26


Conclusion .................................................................................................................. 31


Executive Summary Microsoft® Exchange is one of the most popular and widely used e‐mail applications today. The increased company‐wide reliance upon e‐mail for business operations and the individual requirements of users create the need for an e‐mail solution for companies of all sizes, not just the largest corporations. The designed messaging infrastructure should be flexible to meet the security, availability and scalability needs of an organization. In an effort to reduce the complexity in choosing messaging solutions for companies of all sizes, Dell has performed extensive testing and characterization of Microsoft® Exchange Server 2007 on standard Dell building blocks. The collective knowledge earned through Dell tests and laboratory experiments is incorporated in the Dell Exchange 2007 Advisor tool. This paper discusses in detail the sizing features implemented in Dell Exchange 2007 Advisor Tool and deployment guidance for three Reference architectures of small, medium and large Exchange environments. The recommended reference architectures for the 3 deployment scenarios are built on industry‐standard Dell components providing secure and available infrastructures that are scalable to accommodate future growth needs.


Introduction E‐mail has effectively replaced the telephone as the most essential and important productivity tool for businesses. Whether in the office or on the road, communicating internally or externally with customers, business users depend on e‐mail for their communication needs. The increased company‐wide reliance upon e‐mail for business operations and the individual requirements of users create the need for an e‐mail solution for companies of all sizes. Such a solution should be less complex to manage and also meet business requirements such as security, regulatory compliance and availability. Microsoft Exchange Server 2007 incorporates features that enable businesses to effectively meet those challenges, without fundamentally altering the traditional methods used by end users to access e‐mail. Dell has performed extensive testing and characterization of Microsoft Exchange Server 2007 on Dell PowerEdge servers and Dell™ PowerVault™ and Dell | EMC storage to design solutions that meet the challenging customer requirements. The data from the comprehensive performance tests and the resulting best practices gained have been incorporated in the form of a sizing tool ‐ Dell Exchange 2007 Advisor. The following sections of this white paper explain the Dell Exchange 2007 Advisor and step through the tool outputs designed for small, medium and large business needs.


Dell Exchange 2007 Advisor The Dell Exchange 2007 Advisor has been designed as an “easy to use tool” that can create a draft or general architecture for the backend Exchange infrastructure while providing a complete view of hardware, software, and services offerings that are required to meet customer requirements. The primary goal of this tool is to obtain messaging requirements at a complexity level that does not require IT administrators to provide inputs. Through iteration, customers can plug different requirements into the sizing tool themselves and effectively understand the type of deployment needed prior to contacting their account team. The following sections elaborate on the Exchange Advisor 2007 input questions that enable capturing messaging requirements in less complex terms.

Addressing Business Needs

Figure 1: Question 1‐ Addressing Business needs There are many business reasons that IT managers will choose to upgrade to or deploy Exchange Server 2007. These reasons may arise from a need to consolidate servers and storage or to address security, archiving, compliance, or disaster recovery needs. The question in Figure 1 is designed to capture those needs or issues that businesses would like to address with Exchange Server 2007. For each of these business needs, Dell provides a suite of professional services offerings that include deployment, migration, and maintenance of Exchange Server 2007 solutions.


Price versus Performance

Figure 2: Question 2 ‐ Price versus Performance In addition to understanding the business needs for deploying or migrating to Exchange Server 2007, Dell understands that many different solutions can satisfy a given set of criteria requirements. Sometimes the need for the best system performance to effect best possible user experience can be the business priority, instead of choosing a balanced price/performance configuration. Some higher performance components have an added price premium associated with them, which may not be necessary for all classes of business use cases, so a choice to optimize the solution for performance or for price is offered.


Number of Mailboxes

Figure 3: Question 3 ‐ Number of mailbox users and usage profiles There are many variables directly related to an end user’s mailbox that need to be considered when developing a messaging solution. Average mailbox size and number of mailboxes are two significant factors. Dell’s Exchange Advisor 2007 sizing tool can size up to 15000 mailboxes with an average size up to 2GB These are not the only factors for mailbox design that need to be understood. Just as important as the quantity and size of the mailboxes is the nature of the users, which can have different impacts on the memory, processor and disk resource requirement of the Exchange 2007 environment. Dell has classified Exchange users into three categories: Light, Medium and Heavy users. • Light users send 5 e‐mails and receive 20 e‐mails in an 8 hour period. • Medium users send 10 e‐mails and receive 40 e‐mails in an 8 hour period. • Heavy users send 20 e‐mails and receive 80 e‐mails in an 8 hour period The Exchange 2007 sizing tool allows customers to specify a total of 15000 users distributed over the three categories to better estimate the processor, memory and disk requirements needed to meet the total user needs. In addition to the disk drive storage required for hosting mailbox data, additional disk drives are required to host the transaction logs. Transaction logs are a record of messages sent and received, and are used primarily to maintain consistency and to ensure the recoverability of mailbox data. Proper capacity planning must account for transaction logs. Along with the mailbox data and transaction logs, RAID volume types and performance response times help determine the disk drive count and configuration. Best practices determined through Dell’s characterization studies have determined that a RAID 10 or a RAID 1 volume is always appropriate for hosting the transaction logs. For hosting the mailboxes, the appropriate RAID type is more dependent on the nature of the users and the load being exerted on the mailboxes. If deployments are weighted towards heavier loads, RAID 10 volumes become necessary due to the


demands placed on the physical hard drives. For lighter loads, a RAID 5 implementation can provide the necessary performance while requiring a smaller disk drive count footprint.

Mailbox Size

Figure 4 ‐ Question 4: User mailbox size The mailbox size is one of the important factors in estimating the initial capacity of the storage system that will host the mailboxes. The mailbox size should be carefully chosen to satisfy the growing needs of the organization. Besides the growing needs of users, the actual mailbox requires some additional space such as free‐pages required for database activities, space for deleted items stored until retention period, space for defragmentation and other NTFS overheads. In addition, if the mailbox is also enabled for unified messaging, then extra space is required to save voice messages and fax attachments. User e‐mail mailboxes have evolved to become information repositories for the organization, besides facilitating communications. This raises the need for securing and archiving mailbox information to meet regulatory compliance and retention requirements. Exchange Server 2007 includes a “Messaging Retention Management” feature enabling central management of user personal folders. Also the enhanced and sound journaling features in Exchange Server 2007 enable suitable archiving solutions within the Exchange infrastructure, or integrating with Windows Sharepoint services or with third party archiving solutions. This question in Figure 4 enables capturing the organization’s mailbox size requirements. The 2048 MB limit in the tool is based on the current best practice trends for mailbox sizes in the Industry. Exchange Server 2007 can scale beyond this 2048MB limit specified in the tool for mailbox size. Mailbox size and usage profile determine the disk subsystem sizing. Mailbox size determines the disk space requirements and the usage profile determines disk I/O performance


requirement. Table 1 describes how mailbox characteristics drive storage subsystem disk requirements. Mailbox Characteristics

Light Usage Heavy Usage

Requirement: Low I/O and Less space Heavy I/O and less Space Small Mailbox

Size Recommendation: Low capacity drives

with RAID 5 Low capacity drives with RAID 1/0

Requirement: Low I/O and large space

Heavy I/O and large space Large Mailbox

Size Recommendation:

Large capacity drives with RAID 5

Large capacity drives with RAID 1/0 or RAID5

*Choosing between 10K or 15K RPM disk drives affect the required number of drives and total cost. Generally 10K drives are recommended for Low I/O scenarios and 15K drives for Heavy I/O scenarios Table 1 ‐ Disk subsystem planning based on mailbox characteristics

Cached Mode

Figure 5: Question 5 ‐ Percentage users in cached mode


The cached mode clients versus the online mode clients are a crucial factor for determining the average I/O operations (IOPS) exerted by the mailbox server on the disk subsystem. The cached mode Outlook clients use a local copy of their mailbox for operations and reduce the I/O load on the mailbox server due to local cache access. The online mode clients access the server for all operations and incur significant I/Os on the mailbox server due to their direct access to disk. The cached mode clients periodically synchronize with the mailbox server in the background to keep the mailbox updated. More clients working in online mode cause an increase in I/O operations on the mailbox server which in turn requires more disk‐drives to satisfy that IOPS requirement. Therefore, it is necessary to find the percentage of clients that can be placed in cache mode versus online mode to determine the number of disk drives required to support the load. Question 5 in Figure 5 helps identify the cached mode versus online mode split to accurately size the disk subsystem. Cached mode helps reduce mailbox database I/O operations to disk. Most of this reduction is realized due to the substantial decrease in database read operations from disk. Due to this reduction in disk read operations the read/write ratio of Exchange database operations to disk changes with cached mode. This change in read/write ratio to disk also has a significant impact on disk sizing for the Exchange server.

Data Availability

Figure 6: Question 6 ‐ Data Availability Business Continuity Volumes (BCV) or disk based data copies are an important factor to consider while planning for data availability and backups. When the database backup/restore time duration exceeds the backup/restore window defined within organization’s service agreement, disk copies can be used for backup/restore instead of tape devices, which are traditionally slow. Disk copies also enable quick recovery from data‐level disasters such as user errors. Data copies can be implemented using Local Continuous Replication (LCR) or third party hardware


mechanisms implemented via Volume Shadow copy Service (VSS). Deployments usually implement a hybrid solution, utilizing BCV technologies for quick recovery capabilities, and implementing tape backup solutions that back up the BCV data copies to tape for long term recovery and archiving. Local Continuous Replication is a built‐in replication technology available in Exchange 2007 to create and maintain a copy of the production database on a different set of volumes within the same mailbox server. Volume Shadow copy Service (VSS) is a Windows Server 2003 service that enables third party mechanisms such as EMC SnapView to provide hardware based data copies of application volumes such as Exchange database volumes. These data copies are hosted on a separate set of disks on the storage system. The question in Figure 6 enables capturing BCV requirements for the deployment. If BCV is required for the deployment, an additional set of disk drives needs to be planned in the disk subsystem that will host the data copies of Exchange volumes. These additional drives will be based both on space and IOPS requirement of the BCV solution. Also the BCV technologies may need additional server resources such as processor and memory for execution.

High Availability

Figure 7: Question 7 – High Availability High availability refers to improving the up‐time of an application service or system for client access. Application or system downtime periods may be due to failures or maintenance. High availability for mailbox server can be achieved by deploying a cluster using Microsoft Cluster Services (MSCS). Exchange Server 2007 supports two types of clustering – Single copy Clusters (SCC) based on MSCS shared storage clustering and Cluster Continuous Replication (CCR) based on MSCS Majority Node Set (MNS) replicated storage clustering. The question in Figure 7 captures the high availability needs for the mailbox servers.


Single copy clusters (SCC) is based on the MSCS (Microsoft Cluster Service) shared storage cluster model and manages a single copy of the storage groups and mailbox databases on a shared storage. It uses clustered mailbox servers in active/passive node configuration connected to the shared storage. In the event of a failure on the active server that is serving clients, the passive server continues hosting the mailbox databases from the shared storage. This type of clustering was also available in the previous versions of Exchange Server. Local data copies based on the Exchange Server 2007 LCR feature cannot be enabled on the mailbox servers that are part of the SCC cluster. Cluster continuous replication (CCR) is a new feature based on the MSCS Majority Node Set (MNS) clustering. It combines the replication features in Exchange 2007 with failover features in MSCS. A primary server hosts the databases and serves the clients. A secondary server maintains a copy of the databases and takes over if the primary fails. The secondary copies are kept consistent and synchronized by copying and replaying log records from the primary server. The secondary copies of the database can be used for backup purposes without impacting the performance on the primary production databases. Such a hybrid strategy can also improve the duration and frequency of tape backup strategies for the solution. Both SCC and CCR require additional servers for the passive roles in the cluster. CCR in addition requires separate storage disk drives for the secondary copies of the database. Also, if the secondary database copies are provided on a separate storage system, then CCR can improve resiliency by hosting the secondary server and storage on a separate datacenter.

Hard Drive Speeds

Figure 8: Question 8 ‐ Hard drive speed The selection of a particular hard drive speed is crucial for determining the number of disk drives required in the storage system. As discussed in the earlier sections, both space requirements and performance requirements in terms of IOPS determine the number of disk drives. The mailbox


server IOPS requirement is determined by the user profile and number of users. The space requirement is determined by the mailbox size, overheads and number of users. 15K RPM drives provide better throughput than the 10K RPM drives in terms of IOPS. As a general rule of thumb, 15K RPM drives provide up to 180 IOPS and 10K RPM drives provide up to 120 IOPS. Thus, to support a given IOPS workload based on user profiles, fewer 15K drives are required than 10K RPM drives. The 15K RPM drives provide this improved performance at a higher cost per drive. The difference between choosing these two drives types in small deployments using few drives would not be that significant. However, for large database deployments with heavy IOPS requirements, the 10K RPM drives required will be extremely costly compared to 15K RPM drives. The price difference becomes a significant factor in such deployments. Besides drive costs, IT shops also standardize on drive types as a best practice for management. Generally in such scenarios preference is given for one drive type over another. The question in Figure 8 enables capturing the drive type requirements for the deployment. Generally the number of 15K RPM drives required will be lesser than 10K RPM drives to support the workload profiles. The exception to this would be when space requirements warrant deploying a higher number of disk drives than the IOPS performance requirements and when 10K RPM drives have a higher capacity drive supported than the 15K RPM drives. Such deployments usually include large mailbox sizes with light usage by users.

Storage Topology

Figure 9: Question 9 ‐ Storage Topology The question in Figure 9 enables capturing the storage‐attach technology requirements for the deployment. Usually IT departments standardize or prefer particular attach technology for external storage. Dell Exchange Advisor 2007 supports direct attached external storage based on SAS and Fibre Channel technologies. It also supports SAN based external storage based on Fibre Channel for external storage. Choosing one type over another is usually based on factors such as


cost, ease of management, performance and scalability. Dell™ PowerVault™ MD1000 is a SAS based direct attached storage that provides expandability and performance at a low cost. The Dell | EMC CX3‐20, CX3‐40 and CX3‐80 storage offer flexibility, scalability and performance coupled with manageability in both SAN attached and direct attached Fibre Channel configurations. The Table 2 shows the supported storage systems and their features.

Storage Systems Direct Attach

SAN Attach

Attach Technology

Primary Drive Technology

Max. Drive Speed (RPM)

Max. Drives per Attach

Dell | EMC CX3‐20 � � FC FC 15K 120 Dell | EMC CX3‐40 � � FC FC 15K 240 Dell | EMC CX3‐80 � � FC FC 15K 480 Dell PowerVault MD1000 � SAS SAS 15K 45

*Above storage systems supported with Exchange 2007 Advisor at the time of initial release in April 2007. Supported systems may change in future revisions of the tool. Table 2: Exchange Advisor 2007 supported storage systems The storage performance requirements of a database application like Exchange primarily depend on the throughput provided in terms of IOPS. The IOPS throughout is directly related to the drive speed and number of drives provided. Since Dell PowerVault and Dell |EMC storage systems support both 15K and 10K drives, the throughput performance is usually not a factor in choosing the storage. Other factors such as cost, scalability and manageability determine the choice of storage.


Tape Backup

Figure 10: Question 10 – Tape Backup Replication technologies discussed in earlier sections provide fast backup/restore options for mailbox data and provide continuously updated near‐time copy of the running database. However, they do not provide point‐in‐time data copies that span a longer period of time. The regular backup options provide point‐in‐time copies for recovering a database to any old clean state and also options for storing on resilient storage media such as tapes. Selecting a regular tape backup, in addition to the replication and availability methods, is considered a best practice solution. Tape solutions with large backup space can retain multiple past point‐in‐time copies that span across very long periods of time. Exchange Server 2007 supports backing up LCR and CCR data copies in addition to production databases. A hybrid backup scheme can be built with these options – using LCR for daily incremental backups and tape based regular backup for weekly or longer term data backups.


Anti-Virus / Anti Spam

Figure 11: Question 11 – Anti-virus/Anti-spam solution The threat from viruses and spam has become one of the biggest concerns in any IT deployment and Exchange is no exception. In Exchange 2007, the Edge Transport server role provides anti‐virus/anti‐spam protection and filtering capabilities at the perimeter network. Dell also supports Symantec Mail Security appliances for anti‐virus/ anti‐spam and content filtering at the perimeter network. Dell strongly recommends implementing the antivirus/spam solutions to reduce the amount of unsolicited e‐mails and viruses in the Exchange environment. The question in Figure 11 enables capturing anti‐virus/anti‐spam requirements for a deployment. The tool then appropriately recommends an anti‐virus/anti‐spam solution.


Additional Exchange Server Roles

Figure 12: Question 12 – Additional Exchange Server 2007 Roles Besides the Mailbox server role, Exchange 2007 includes other server roles to perform various functions. The Hub Transport server role is required in any exchange 2007 deployment and is responsible for handling all internal mail flow across Exchange roles and appropriate delivery of user messages. The Client Access server role hosts services and functions required for supporting a variety of mail clients including Outlook Web Access (OWA) and mobile messaging. The Edge Transport server role sits in the perimeter network and provides functionality for routing external SMTP mail flow to and from the Internet. The Unified Messaging (UM) server role provides the new Exchange Server 2007 functionality for integration of voice mail and fax along with e‐mail into user mailboxes. It also provides for Outlook Voice Access functionality, which allows users to access e‐mail, voice mail, and calendar entities from a telephone. The server roles or a subset of roles can be consolidated and deployed on the same server hardware system with a few exceptions. If the Mailbox server is clustered using SCC or CCR, then no other role can be consolidated with it. The Edge Transport server role sits outside the Active Directory framework in the perimeter network and hence cannot be consolidated with other roles. The Hub Transport and Client Access roles are required per Active Directory site in the organization. Hence when the Mailbox server role is clustered, a separate server system is required to host these roles. The question in Figure 12 enables capturing the additional role requirement for a deployment. The tool then recommends an appropriate server system for each of the additional role functionality selected. Refer to the Dell whitepaper titled “Exchange Server 2007 Design Considerations” to learn more about Exchange Server roles and their deployment considerations.


Exchange 2007 Reference Architecture The following sections enumerate three different classes of deployments: small, medium and large. The three classes of users will be characterized based on the number and size of mailboxes, the nature of their use, the size of their deployment, and availability needs. An appropriate solution will be presented for each type of deployment with the rationale for the inputs and explanation of the recommended solution.

Small Exchange Deployment – Up to 500 Users The first reference architecture represents a relatively small Exchange organization with up to 500 heavy users having an average mailbox size of 150 MB. Table 3 summarizes the requirements for this organization:

Number of Mailboxes 500 Average Mailbox size 150 MB User Profile Heavy Storage Direct Attached SAS Data Replication Using LCR High Availability None Backup Required? Yes

Table 3: Small Exchange Requirements

Several critical factors must be considered before arriving at a suitable platform for your Exchange deployment. Some of the considerations include:

• Appropriate server platform with required number of processors, memory and I/O expandability.

• Suitable storage technology with future growth and scalability in mind. • High availability requirements. • Backup methodology.


Exchange Server Layout Recommendations:

Exchange Mailbox/Hub Transport/ Client Access Server Dell PowerEdge 1950

Processors 2 x Dual Core Intel Xeon Memory 8 GB Number of Exchange Storage Groups 4 Number of Exchange Information Stores 4 Size of each Exchange Information Store 19 GB Tape Backup Drive PowerVault 100T LTO‐3 Tape Drive

Table 4: Exchange Server Recommendations for Small Exchange Deployment As shown in Table 4 above, a Dell™ PowerEdge™ 1950 with two dual‐core processors is the recommended server platform for this environment. The Mailbox, Hub Transport and Client Access server roles can be consolidated on the same physical server. The Dell PowerEdge 1950 has sufficient processing capability to handle the Mailbox services and all the message transportation services required by other server roles. If the Unified Messaging server role or Edge Transport server role is required, additional physical servers may be required. If the Edge Transport server is not a part of the organization, then the Hub Transport server can be configured to relay Internet messages. This deployment assumes that the Mailbox server is not deployed in a highly available (HA) clustered environment. If HA is required for the Mailbox server role using Single Copy Clusters (SCC) or Cluster Continuous Replication (CCR), no other role can be consolidated with the Mailbox role on the same server.


Figure 13: Small Exchange Architecture with LCR Deployment Based on the user load, the minimum memory required for the Exchange server is 8 GB. This amount of memory will be suitable for serving four storage groups and additional RAM may be required for supporting more storage groups.

Storage recommendations: The following are the storage recommendations using RAID 10 for Exchange information stores:

Storage System Dell PowerVault MD1000 Total number of drives 10 Total number of enclosures 1 Drives for Exchange Information Stores 4 x 73GB 15K SAS using RAID 10 Drives for Transaction Logs 2 x 36GB 15K SAS using RAID 1 Drives for LCR 3 x 300GB 15K SAS using RAID 5 Number of drives for hot spare 1 x 300GB 15K SAS

Table 5: Storage Recommendations for Small Exchange Deployment Using RAID‐10


The following are the storage recommendations using RAID 5 for Exchange information stores:

Storage System Dell PowerVault MD1000 Total number of drives 12 Total number of enclosures 1 Drives for Exchange Information Stores 6 x 36GB 15K SAS using RAID 5 Drives for Transaction Logs 2 x 36GB 15K SAS using RAID 1 Drives for LCR 3 x 300GB 15K SAS using RAID 5 Number of drives for hot spare 1 x 300GB 15K SAS

Table 6: Storage Recommendations for Small Exchange Deployment Using RAID‐5 Several factors are considered while determining the type and capacity of the storage system. Database LUN capacity depends on the mailbox quota as well as some other factors such as the whitespace or free‐pages required by the database, space for deleted items stored until retention period, space for defragmentation and other NTFS overheads. Log LUN capacity depends on how far in the past the logs should be backed up or replayed to restore database design of an organization. Additionally, Exchange is an I/O intensive application and all client activity causes updates to the Exchange database, which produces I/O operations to disk. The disk subsystem should be capable of meeting these demands. It is therefore important to size the disks for performance and not just for capacity of the mailboxes. Based on these factors two storage recommendations are presented: using RAID 10 and RAID 5 for Exchange information store. RAID 10 offers the best performance with high protection, but only 50% of the RAID group capacity is usable. RAID 5 offers a higher usable capacity per RAID group than RAID 10. It can be effective for environments with very large mailboxes and/or lower IOPS requirements. Considering the capacity and IOPS requirements for this environment, the Dell PowerVault MD1000 is a suitable storage platform. This array utilizes enterprise‐class technology with high‐performance drives that are suitable for Exchange workloads. It provides balanced capacity and excellent I/O performance with 10K and 15K RPM SAS drives. Table 5 and Table 6 explain the drive configurations for the RAID 10 and RAID 5 solutions.

Backup and Availability Recommendations: To achieve mailbox resiliency, at a minimum Dell recommends using Local Continuous replication (LCR) to reduce the recovery time for data‐level disasters. LCR maintains a local copy of the mailbox database on the Mailbox server and keeps the copy consistent with the production database by replaying log records on them. The database copies can be manually switched to function as production databases during failures or during maintenance. For a Mailbox server enabled for LCR operation, additional hardware resources are required to store the production data and handle LCR related IOPS load. The majority of the additional resource consumption comes from log updates through reads and writes on the passive copy. For this reference architecture, the above mentioned processors and memory recommendations for the PowerEdge


server should be sufficient to implement LCR. However, the storage system would require additional drives to store the passive copy of production LUNs. As shown in Table 5 and Table 6, three 300GB, 15K RPM SAS drives configured using RAID 5 is required for the passive copy. Even though Local Continuous Replication provides a level of protection for mailbox data, it cannot replace the regular database backup because it only provides continuously updated near‐time copy of the active database. Regular backup options provide past point‐in‐time copies for recovering a database to any old clean state. The passive LCR copy can be used as the source for backup. This can reduce the impact of the backup operation on the active database. Dell recommends using PowerVault™ 100T LTO‐3 tape drive, which has a maximum capacity of 400GB and maximum backup speed of 243GB/hour.

Medium Exchange Deployment – Up to 1000 Users The medium size Exchange reference architecture represents an Exchange organization with up to 1000 heavy users having an average mailbox size of 250 MB. As the number of users increases, the messaging infrastructure needs to grow to support the additional workloads and features. Table 7 summarizes the requirements for this organization:

Number of Mailboxes 1000 Average Mailbox size 250 MB User Profile Heavy Storage Direct Attached SAS High Availability Using CCR Backup Required? Yes

Table 7: Medium Exchange Requirements



Exchange Mailbox – Primary site Dell PowerEdge 1950 Processors 2 x Dual Core Intel Xeon Memory 8 GB Exchange Mailbox – Secondary site Dell PowerEdge 1950 Processors 2 x Dual Core Intel Xeon Memory 8 GB Exchange Hub/CAS Server Dell PowerEdge 2950 Processors 2 x Dual Core Intel Xeon Memory 8 GB Number of Exchange Storage Groups 8 Number of Exchange Information Stores 8 Size of each Exchange Information Store 31 GB

Table 8: Exchange Server Recommendations for Medium Exchange Deployment

As shown in Table 8 above, the following are the recommended server platforms for this reference architecture:

• Exchange Mailbox Server:

- Dell™ PowerEdge™ 1950 with two dual‐core processors

- 8 GB RAM

• Exchange Hub Transport/ Client Access Server:


- 8 GB RAM


Figure 14: Medium Exchange Architecture with CCR Deployment If Unified Messaging or Edge Transport server roles are required, additional physical servers may be required. If the Edge Transport Server is not a part of the organization, then the Hub Transport server can be configured to relay Internet messages. This reference architecture includes Cluster Continuous Replication (CCR). CCR is based on MSCS Majority Node Set (MNS) clustering, wherein a copy of the mailbox databases is hosted on another server with its own storage space. Mail clients access the primary server, and database changes to it are shipped to the secondary server in the form of log records. The shipped log records are played on the secondary server to keep the secondary database copies consistent with the primary. If the primary Mailbox server fails, the MNS clustering mechanism automatically promotes the secondary server to start serving the clients. CCR provides both mailbox high availability and also site recovery through hosting the secondary server on a separate datacenter. Since CCR is used for high availability, no other Exchange server role can be consolidated with the Mailbox role on the same server. Therefore the Hub and CAS server roles have been split to a separate server. The Dell PowerEdge 2950 with two dual core Intel Xeon processors and 8 GB of RAM is a suitable platform for these roles.


Storage recommendations: The following is the storage recommendations for the primary CCR site using RAID 10 for Exchange information stores:

Storage System Dell PowerVault MD1000 Total number of drives 13 Total number of enclosures 1 Drives for Exchange Information Stores 8 x 146GB 15K SAS using RAID 10 Drives for Transaction Logs 4 x 36GB 15K SAS using RAID 10 Number of drives for hot spare 1 x 146GB 15K SAS

Table 9: Storage Recommendations for Medium Exchange Deployment Using RAID‐10 An identical storage configuration with 13 drives is required for the secondary CCR site. The following is the storage recommendations for the primary CCR site using RAID 5 for Exchange information stores:

Storage System Dell PowerVault MD1000 Total number of drives 15 Total number of enclosures 1 Drives for Exchange Information Stores 10 x 73GB 15K SAS using RAID 5 Drives for Transaction Logs 4 x 36GB 15K SAS using RAID 10 Number of drives for hot spare 1 x 146GB 15K SAS

Table 10: Storage Recommendations for Medium Exchange Deployment Using RAID‐10 An identical storage configuration with 15 drives is required for the secondary CCR site. Two storage recommendations are presented: using RAID 10 and RAID 5 for Exchange information store. RAID 10 offers the best performance with high protection, but only 50% of the RAID group capacity is usable. RAID 5 offers a higher useable capacity per RAID group than RAID 10. It can be effective for environments with very large mailboxes and/or lower IOPS requirements. Considering the capacity and IOPS requirements for this environment the Dell PowerVault MD1000 is a suitable storage platform. This array utilizes enterprise‐class technology with high‐performance drives that are suitable for Exchange workloads. It provides balanced capacity and excellent I/O performance with 10K and 15K RPM SAS drives. Table 9 and Table 10 explain the drive configurations for the RAID 10 and RAID 5 solutions.


Backup and Availability Recommendations: Deploying a high availability solution for database related applications is always considered a best practice to avoid failure scenarios. Dell recommends using CCR to ensure application as well as data availability. To implement CCR, a secondary site with storage and server configuration identical to the primary Exchange Mailbox server is required. Figure 14 shows a passive Exchange Mailbox server and storage system allocated for CCR.

Tape Back up PowerVault TL4000 Tape Library Tape Backup server PowerEdge 1950 Processors 2 x Dual Core Intel Xeon Server memory 4 GB

Table 5: Tape Backup Recommendations for Medium Exchange Deployment Additionally, PowerVault™ TL4000 tape backup library is recommended to create point in time backups of the Exchange server data. The tape library attaches to a separate PowerEdge 1950 server known as the backup server. The backup server connects to the Exchange servers over the LAN to conduct the backup. This centralized approach helps simplify backup administration.

Large Exchange Deployment - Up to 5000 Users As a messaging infrastructure grows in size, it typically brings more complexity. The message routing services and policies overhead increases and requires more hardware resources to satisfy the growing bandwidth requirements. The large Exchange reference architecture represents an Exchange organization with up to 5000 heavy users having an average mailbox size of 1 GB. Table 12 summarizes the requirements for this organization:

Number of Mailboxes 5000 Average Mailbox size 1 GB User Profile Heavy Storage SAN Attached Fiber Channel High Availability Using SCC Backup Required? Yes

Table 12: Large Exchange Requirements



PowerEdge 6950 or Exchange Mailbox –Active

PowerEdge 6850 4 x Dual Core AMD Opteron or

Processors 4 x Dual Core Intel Xeon

Memory 32 GB PowerEdge 6950 or

Exchange Mailbox –Active PowerEdge 6850 4 x Dual Core AMD Opteron or

Processors 4 x Dual Core Intel Xeon

Memory 32 GB Exchange Hub Transport Server Dell PowerEdge 2950 Processors 2 x Dual Core Intel Xeon Memory 6 GB Exchange CAS Server Dell PowerEdge 2950 Processors 2 x Dual Core Intel Xeon Memory 4 GB Number of Exchange Storage Groups 40 Number of Exchange Information Stores 40 Size of each Exchange Information Store 125 GB Table 13: Exchange Server Recommendations for Large Exchange Deployment As shown in Table 13 above, the following are the recommended server platforms for this reference architecture are:

• Exchange Mailbox Server:

- Dell™ PowerEdge™ 6950 or Dell PowerEdge 6850 with four dual‐core processors

- 32 GB RAM

• Exchange Hub Transport Server:


- 6 GB RAM

• Exchange CAS Server:

- Dell PowerEdge 2950 with two dual‐core processors

- 4 GB RAM

For a large number of mailboxes, the best practices involve scaling out all the Exchange server roles on separate servers. The physical separation of the server roles will provide better utilization of resources and good performance. Another reason for separating the Mailbox server is to allow implementing high‐availability clustering option using Single


Copy clusters (SCC). SCC is based on Microsoft Cluster Services (MSCS) shared storage clustering, wherein a single copy of the databases resides on a shared external storage connected to two Mailbox server nodes. One of the server nodes, called the “active” node, hosts the mailbox databases and serves the clients. If the “active” node incurs a failure, the other node, called the “passive” node, takes over hosting mailbox databases from the shared storage and continues serving the clients.

Figure 15: Large Exchange Architecture with SCC Deployment


Storage recommendations: The following are the storage recommendations using RAID 10 for Exchange information stores:

Storage System Dell|EMC CX3‐20 Total number of drives 86 Total number of disk array enclosures 6 Drives for Exchange Information Stores 60 x 300GB 10K FC using RAID 10 Drives for Transaction Logs 18 x 73GB 10K FC using RAID 10 Number of drives for hot spare 3 x 300GB 10K FC Storage OS drives 5 x 73GB 10K FC

Table 14: Storage Recommendations for Large Exchange Deployment Using RAID‐10 The following are the storage recommendations using RAID 5 for Exchange information stores: Storage System Dell|EMC CX3‐20 Total number of drives 96 Total number of disk array enclosures 7 Drives for Exchange Information Stores 70 x 300GB 10K FC using RAID 5 Drives for Transaction Logs 18 x 73GB 10K FC using RAID 10 Number of drives for hot spare 3 x 300GB 10K FC Storage OS drives 5 x 73GB 10K FC Table 15: Storage Recommendations for Large Exchange Deployment Using RAID‐5 Two storage recommendations are presented: using RAID 10 and RAID 5 for Exchange information store. RAID 10 offers the best performance with high protection, but only 50% of the RAID group capacity is usable. RAID 5 offers a higher usable capacity per RAID group than RAID 10. It can be effective for environments with very large mailboxes and/or lower IOPS requirements. Considering the capacity and IOPS requirements for this environment the Dell | EMC CX3‐20 is a suitable storage platform which can support for up to 120 FC drives. Table 14 and Table 15 explain the drive configurations for the RAID 10 and RAID 5 solutions.

Backup and Availability Recommendations: Implementing Single Copy Cluster (SCC) will require an additional PowerEdge™ 6850 or 6950 server with same hardware configuration as the active Mailbox server. The additional installed server acts as the passive Mailbox server and shares the same storage system with the active Mailbox server. In the event of a failure on the active mailbox server, the Exchange Mailbox server role fails over to the passive node and resumes activity.


Tape Back up PowerVault ML6030 CM Library Tape Backup server PowerEdge 2950 Processors 2 x Dual Core Intel Xeon Server memory 4 GB

Table 16: Tape Backup Recommendations for Large Exchange Deployment For this environment, the PowerVault™ ML6030 CM Library is the recommended tape backup device. Additionally, the Dell PowerEdge 2950 may be used as the tape backup server. The backup server connects to the Exchange servers over the LAN or SAN to conduct the backup. This centralized approach helps simplify backup administration. The network topology for SAN‐based backups is designed to improve application performance because it is routed over a high‐speed Fibre Channel network.


Conclusion In messaging deployments with Exchange Server 2007, there are many different criteria that can affect how servers and storage need to be sized. These factors impact memory, processor and disk utilization and can vary greatly from one implementation to the next. Because of the work performed at Dell Labs to actively characterize the Mailbox role of Exchange Server 2007 on Dell’s enterprise server and storage portfolio, Dell is able to provide deployment recommendations. In order to make those recommendations accessible to customers, Dell developed the online Exchange 2007 Advisor Tool. The discussion about the tool output for the three defined reference architectures was intended to provide an insight into how the recommendations are calculated. To calculate the requirements for any configuration, the tool can be accessed at http://www.dell.com/exchange. THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND. © Dell Inc. 2007. All rights reserved. Dell, PowerEdge, PowerVault, and the Dell logo are trademarks of Dell Inc. Microsoft is a registered trademark of Microsoft Corporation. Other trademarks and trade names are the property of their respective owners and Dell disclaims proprietary interest in the marks and names of others.

advisor and representative deployments...figure 5: question 5 ‐ percentage users in cached mode...

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