A Dell Technical White Paper

Dell │ Database Solutions Engineering

Leena Basanthi

SQL Server 2008 R2 Data Protection Using DPM 2010 and Dell EqualLogic ™ PS Series Arrays

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Executive Summary

In today’s organizations, most of the mission-critical systems have all of their data housed in Database Management Systems (DBMS). One of the most popular relational databases on Microsoft® Windows® is Microsoft SQL Server™, which serves as a critical component for many of the business intelligence and e-business applications. If a database server crashes, due to planned or unplanned events such as mistakes, viruses, or database corruption, a business could face downtime resulting in lost revenue, productivity, and customers. Organizations should make sure to design and implement an effective business continuity plan for the success and sustenance of their businesses. A rapid and reliable data protection strategy is needed for availability of system critical applications whose data is housed in SQL server databases. Microsoft System Center Data Protection Manager 2010 (DPM 2010) in conjunction with Dell™ EqualLogic™ storage systems, brings you a complete data protection solution for Microsoft SQL Server 2008 R2 that also enables you to have a scalable and easy to manage storage consolidation for enterprises of all sizes. DPM 2010 is a disk-based data protection software application that enhances reliability and provides fast backup windows. This white paper provides best practices for using DPM 2010 for SQL Server 2008 R2 protection combined with Dell EqualLogic storage. The best practices outlined in this paper help customers to ensure a rapid and reliable recovery of a database and eliminate problems faced with traditional backup windows.

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.

© 2010 Dell Inc. All rights reserved. Reproduction of this material in any manner whatsoever without

the express written permission of Dell Inc. is strictly forbidden. For more information, contact Dell.

Dell, the DELL logo, and the DELL badge, EqualLogic, PowerEdge, and PowerConnect are trademarks of

Dell Inc. Microsoft, Windows, SQL Server, and Windows Server are registered trademarks of Microsoft

Corporation in the United States and/or other countries. Intel is a registered trademark of Intel

Corporation in the U.S. and/or other countries.

Other trademarks and trade names may be used in this document to refer to either the entities

claiming the marks and names or their products. Dell disclaims proprietary interest in the marks and

names of others.

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Table of Contents

Executive Summary ....................................................................................................... 2

Overview of System Center Data Protection Manager 2010 ..................................................... 5

Using DPM 2010 With PS Storage for SQL Server Database Protection .......................................... 6

DPM 2010 With PS Storage ............................................................................................ 6

DPM 2010 With SQL Server 2008 R2 ................................................................................. 7

How DPM 2010 Capabilities Blend With PS Storage Features to Provide Near-Continuous Data

Protection for SQL Server 2008 R2 Database ...................................................................... 8

Reference Configuration ............................................................................................ 11

Conclusion ................................................................................................................ 19

References ................................................................................................................ 21

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Introduction Businesses of all sizes often face challenges in protecting database servers that run business-critical online transaction processing (OLTP) and online analytical processing (OLAP). Microsoft SQL Server 2008 R2 is one such comprehensive data management and business intelligence platform that facilitates enterprises to run business-critical applications and to store relational and structured data. Because Service Level Agreements (SLAs) demand application availability online 24x7, many organizations cannot tolerate the impact of losing data stored in a database. To improve the availability of mission-critical applications, it is necessary to develop a comprehensive data protection strategy by considering Recovery Time Objective (RTO) and Recovery Point Objective (RPO)—the key metrics of an effective business continuity plan. An RTO is the amount of time it takes to recover from a disaster event, and an RPO is the acceptable amount of data that you can lose from disruption. The most common strategies for data protection that are driven by these metrics are backups made to tape and sent offsite, backups made to disk on site, replication of data, or high availability systems. Choosing an appropriate strategy that addresses timely data recovery is one of the challenges that IT administrators often face. To minimize the impact of database downtime and improve the business continuance scenarios, enterprises need to choose an optimal backup plan such as near-continuous data protection that supports instantaneous recovery to keep the RPO as small as possible. Microsoft System Center Data Protection Manager 2010 (DPM 2010) is a ―best-of-breed‖ product that offers effective and near-continuous data protection for Windows application servers, such as SQL Server, and that uses Microsoft’s shadow copy technology for continuous backups. DPM 2010 offers an RPO based on how often you are taking a recovery point. When DPM 2010 is used in conjunction with Dell EqualLogic storage and Dell PowerEdge™ servers, they work together to simplify deployment, improve performance, ensure seamless scalability, and provide optimal data protection for key business applications. The Dell EqualLogic PS6010 and PS6510 are the newest series of EqualLogic iSCSI SAN storage systems that add the power of 10GbE technology and provide higher bandwidth performance for mission-critical, high I/O database applications. This white paper focuses on how DPM 2010 works with PS storage 6010 and SQL Server 2008 R2, and on how they are better together in providing a complete business continuity solution.

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Overview of System Center Data Protection Manager

2010 System Center Data Protection Manager 2010 (hereafter referenced as DPM 2010), an integrated member of the Microsoft System Center family of products, is designed to provide near-continuous data protection with a primary focus on servers running Microsoft workloads such as Microsoft SQL Server OLTP/OLAP databases. DPM 2010 enables administrators to implement real-time disk protection for SQL server databases and provides flexibility to both administrators and end users to restore files from backups and restore points. DPM 2010 seamlessly integrates with disk and tape, and it offers data protection methods such as: disk-based (D2D), tape-based (D2T), or a combination of disk-based and tape-based protection (D2D2T). DPM 2010 offers features such as its intelligent GUI for ease of management, strong Power Shell support, and a robust replication and checkpoint system that allows database administrators to perform backups and recoveries quickly and successfully. With the help of the DPM 2010 Administrator Console, end users get a consolidated interface that gives immediate access to the Monitoring, Protection, Recovery, Reporting, and Management task areas as shown in Figure 1.

Figure 1: DPM Administrator Console

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As a part of the Microsoft Windows Server® System, DPM 2010 contains tools like Microsoft Management Console (MMC) to which all of the DPM 2010 reports and alerts are uploaded. DPM 2010 enhances the support with the Self-Service Recovery Tool (SSRT) that enables end users to recover SQL server databases that are backed up by the DPM 2010 server, without any intervention from the DPM 2010 administrator.

Using DPM 2010 With PS Storage for SQL Server

Database Protection DPM 2010 extends its powerful capabilities to deliver near continuous data protection for Microsoft SQL Server 2008 R2. The subsequent sections describe how DPM 2010 blends with Dell EqualLogic Storage and how it works to protect SQL Server 2008 R2. These topics are followed by a series of DPM 2010 features and best practices that are outlined to provide complete database protection.

DPM 2010 With PS Storage

For details about deploying and configuring DPM 2010 with PS storage systems, you can refer to the PS Series Best Practices Deploying DPM 2007 in iSCSI SAN guide from EqualLogic, which is applicable with DPM 2010. This section describes the benefits of using iSCSI SAN storage with DPM 2010, a server software application that provides near-continuous data protection and optimizes disk-based backup and recovery operations. Intelligent PS Series storage is an excellent choice for use as the storage pool resources in DPM 2010 configurations. Deploying DPM 2010 with a PS Series SAN, you can configure a completely redundant environment using Multipath I/O technology, which improves the reliability of the DPM 2010 server. In addition, with a PS Series SAN, you can boot the DPM 2010 server and the protected application servers from the SAN, resulting in a configuration that can support nearly immediate system recovery. PS series storage improves storage utilization efficiency and availability by allowing the administrators to logically over-allocate SAN volumes with features like thin provisioning, in which the current and future storage capacity needs are met, while eliminating the difficulty of adding storage to applications or operating systems that do not support online expansion. This feature enables the allocation of very large volumes on the backend DPM 2010 storage pool for the replication and recovery points that DPM 2010 recommends for the protection group. The storage advanced features such as Clone, Snapshot, Replication, and Performance Monitor can be incorporated into the existing solution at no extra cost to match ease-of-use with ease-of-doing-business. Cloning a volume creates a new volume with the same size and contents as the original volume, which helps to dramatically reduce network overhead during the creation of the initial replica for the protected database. Other features like Snapshot and Replication simplify and improve performance of backup and recovery operations. By replicating volumes from one group to another, you can set up a simple, yet robust disaster recovery plan for the primary group, so that you can promote a replica set to a new volume and snapshots—temporarily or permanently. As a supplement to the Performance Monitor feature of the PS Series array, you can also use the Multiple Router Traffic Grapher (MRTG) to monitor the I/O activity, latency, and throughput of volumes and members. To have consolidated performance and event monitoring across the virtualized Dell EqualLogic SAN, using the EqualLogic SAN HeadQuarters (SAN HQ) management tool is the best option. SAN HQ gives administrators the ability to monitor multiple PS Series groups, get historical

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performance reports, and do trend analysis for capacity planning and troubleshooting from a central interface. With all the preceding features included in Dell EqualLogic PS series 6010, as shown in Figure 2, it serves as an ideal choice as a backend storage pool for DPM 2010 because it optimizes responsiveness of applications through high bandwidth and intelligent tiering of data within the array, and across low-latency Solid State Disk (SSD) and performance sensitive 15K RPM SAS hard disk. The PS 6010 supports high throughput with 10g bandwidth per port.

Figure 2. PS 6010

DPM 2010 With SQL Server 2008 R2 DPM 2010 starts its near-continuous data protection process through a protection group, which is a collection of data sources, and a storage pool that has one or more disks dedicated to store the replicas and recovery points. To fully protect the data source with DPM 2010, the following protection policies must be defined:

What type of data source is being protected?

Which protection method is to be used?

What is the amount of disk space to be allocated in the storage pool?

What is the method of replica creation for the members of the protection group? The DPM 2010 protection process involves creating and maintaining a full replica of the protected data and regularly creating recovery points of the synchronized replica. The replica serves as a full backup of the protected data. In addition, the DPM 2010 recovery process involves choosing a previous version of the data source from the stored recovery points on the DPM 2010 server and then restoring a copy of the selected data to its point of origin on the protected server. How DPM 2010 works to protect SQL Server- During the configuration of the protection group, the user selects the SQL Server either at database level or instance level as the data source to be protected. Each member of a protection group is associated with a replica, which is an initial baseline copy of the protected database. This replica serves as the full backup of the protected data. After a replica is created, DPM 2010 captures express full backups using the SQL Server VSS Writer, which identifies the blocks that have changed in the protected database. Only those blocks are sent to the DPM 2010 server for protection. To keep the replicas synchronized with the data on the protected computers, DPM 2010 incorporates a transactional replication feature that uses application-aware agents that can protect SQL server data through their transaction logs. Therefore, DPM 2010 uses a combination of transaction log replication and block-level synchronization in conjunction with the SQL Server VSS Writer to help ensure a rapid recovery of the SQL server databases. The DPM 2010 stores its replicas, shadow copies, and logs in the storage pool that consists of one or more disks.

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How DPM 2010 Capabilities Blend With Dell Hardware (PS Storage 6010 and

Dell 11g Server-R910) to Provide Near-Continuous Data Protection for SQL

Server 2008 R2 Database?

Each of the following sections explains as how Dell hardware is suitable to protect SQL server 2008 R2 using DPM 2010. The sections describe DPM 2010 capabilities of data protection and recovery method such as data source and protection method selection, protection group configuration that includes recovery goals, disk allocation, replica creation method and consistency check etc., and how all these capabilities blend with EqualLogic features. Dell Power Edge

11g Server-R910: Because DPM 2010 and SQL Server 2008 R2 support scale-up scenarios for the largest available x64 hardware, therefore, deploying it on the Dell 11g PE R910 server is an ideal choice. With Intel® Advanced RAS Technology features, the PE R910 can automatically monitor, report, and recover from hardware errors to maintain data integrity and keep mission-critical services like OLTP/OLAP and backup/recovery applications online. The features, such as Performance resources, power efficiency, I/O, and memory scalability, enables maximizing database workload in a data center and using DPM 2010 servers more efficiently.

Enhancements in DPM 2010: As per Microsoft, DPM 2010 offers protection for up to 2000

databases per DPM 2010 server. DPM 2010 offers Instance-Level Protection with Data Source Collocation, so that all new databases within the instance are auto protected. With the help of the self-service recovery capability, Database administrators can now recover their databases without intervention from the backup administrator or without using the DPM 2010 administrator console. In addition to the preceding description of enhanced support, DPM 2010 automatically grows and shrinks volumes as required, which helps to use the storage more efficiently.

DPM 2010 Protection Methods: DPM provides tape-based and disk-based data protection which can be configured at the protection-group. DPM offers the following protection methods:

Disk-to-disk (D2D). This method is for a short-term protection, in which data from

protected computer is stored on the disk based storage such as DPM 2010 storage pool

or Custom Volumes. With this method, customers can have faster backup and recovery

times.

Disk-to-tape (D2T). This is a traditional method of backing up data. In DPM the data is

backed up from the replica in the storage pool to tape so that there is no network

traffic and no impact on the protected computer. You can also back up data directly

from the protected computer to tape. Enabling co-location of data on tape from

multiple protection groups with the same retention range maximizes tape utilization.

This method gives a means of security as the tapes are stored offsite.

Disk-to-disk-to-tape (D2D2T): This method combines D2D and D2T for extra

protection. Using DPM, data can be backed up on disk and tape through a combination

of full and incremental backups from either the protected computer or the DPM

replica. The D2D2T method provides the quick recovery benefits of disk-based storage

in the short term and tape-based storage in the long term. With DPM 2010 you can

create tape-based archive storage for critical data in long-term, from the disk-based

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replica, with no impact on the computer. The archives that are created from the

replica combine full and incremental backups.

Disk Allocation: To configure a DPM 2010 backend storage pool, RAID 5 configuration offers an effective compromise between capacity, cost, reliability, and performance. However, because the DPM 2010 server workload is composed primarily of write operations, RAID 10 is best suited in terms of reliability, performance, and scalability. DPM 2010 strongly recommends using GPT disks for the DPM 2010 storage pool, which should be twice the size of the protected data for added protection. In DPM 2010, the data co-location feature enables protection of multiple data sources on a single volume or on the same tape, which allows you to store more data on each volume or tape. Disk collocation strongly improves scalability when protecting many small data sources and enables better DPM 2010 server utilization. To enable parallel replication and maximize performance in DPM 2010, users can choose Custom Volumes, which are not part of the DPM 2010 storage pool. But Custom Volume has the following limitations:

o Custom Volumes CANNOT be co-allocated. o Custom Volumes DO NOT support SQL Server Instance level backup.

With advanced EqualLogic thin provisioning, SQL server database volumes or the DPM 2010 storage pool can be preset to a specific size at volume creation. Physical storage is then automatically allocated from the free storage pool as database, replica, or recovery points volumes grow in size. The benefits are simpler management of volumes and more efficient use of physical storage resources.

Replica Volume and Recovery Volume: Each data source of a protection group is associated

with a Replica and Recovery Volume. The replica volume contains the replica for the protected data source, and the recovery volume contains the shadow copies and recovery points for a protected data source. These Volumes can be in either the DPM 2010 storage pool or in the Custom Volumes. The Size of these volumes depends on the size of the protected data, the daily recovery point size, the expected volume data growth rate, and the retention range objectives. When the disk space allocated for Replica Volumes and Recovery Point Volumes exceeds the threshold limit, DPM 2010 generates alerts accordingly for each of the volumes. To resolve this possible issue, users need to add the disks to the storage pool. With the EqualLogic family of iSCSI SANs, users can have a rapid SAN deployment, easy storage management, and seamless expansion. All EqualLogic PS Series arrays are completely interoperable, and they can be mixed and matched to build tiered storage within a single SAN or across SAN groups.

Replica Creation Method: It is a process by which the data sources selected for protection are transferred to the DPM 2010 server storage pool. DPM 2010 can create replicas either automatically over the network or manually. Automatic replica creation is easier, and it is a good option for the Instance level SQL Servers’ protection, for which the disk allocation is the DPM 2010 storage pool. Such large replica creation jobs must be scheduled to run during off-peak hours or when the network traffic is less. The manual replica creation option can be chosen depending on the size of the protected data and the speed of the network. If a critical database of large volume is to be protected, then using the combination of the EqualLogic Clone feature, Custom Volume, and Manual Replica is the best option. This process involves creating a clone of the large volume and assigning it to the DPM 2010 server as a replica volume of storage type Custom Volume and assigning another volume as the Recovery Point Volume. After selecting the Manual Replica option, it is important to copy the cloned content to the DPM 2010 replica folder path, for example: C:\Program Files\Microsoft DPM\DPM\Volumes\Replica\SqlServerWriter\vol_1f447024-985a-4747-a153-

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b4e06c0aa665\7c59f9ad-3846-44e2-85e7-f6b311bcac10\Full\G-Vol\ Failing to do so, results in the automatic replica creation that takes a long time. It is recommended to create a clone when the I/O load is minimal on the application. For more details, refer to the PS Series Best Practices Deploying DPM 2007 in iSCSI SAN guide from EqualLogic, which is applicable with DPM 2010.

Synchronization of Application Data: To provide continuous data protection to the

protected database after the creation of the initial replica, changes are transferred to the DPM 2010 server incrementally through synchronization at regular intervals. This process of synchronizing the replica depends on the type of application and the type of synchronization. DPM 2010 provides the following methods of synchronizing a replica:

Incremental synchronization Synchronization with consistency check

To choose the best suitable synchronization method for database protection, the user should be aware of the following guidelines: DPM 2010 does not support incremental synchronization for the following databases:

master, msdb, databases that are log-shipped and that is in read-only mode or that use the simple recovery model—they use Express Full backups and recovery points are created corresponding to each express full backup.

For all other SQL server databases, synchronization transfers a transaction log backup, and

recovery points are created for each incremental synchronization and express full backup. But synchronization frequency should be selected based on how much data loss you can tolerate.

Running a consistency check is another process of synchronization that involves checking

inconsistencies between the replicas and the protected data source. The time taken to complete this process depends on the discrepancies.

For heavy workload applications like SQL Server R2 databases, it is recommended to

perform consistency checks during off-peak hours because it affects the performance of the protected computer, the DPM 2010 server, and the network. However, it is expected to be optimized because only the changes and checksums are transferred during this process.

Network Throttling: The network traffic can be throttled by setting limits for maximum

network utilization to minimize the impact of the DPM 2010 server’s primary operations on the network. Throttling helps to ensure that network bandwidth is available to other applications and to limit the amount of network bandwidth that the DPM 2010 server can consume during operations like replica creation, synchronization, and consistency checks. However, users should bear in mind that the network throttling ability can lengthen the amount of time for these operations to complete. The network bandwidth usage throttling can be set in terms of a fixed amount of data to be transferred during the defined peak/non-peak hours. Unless the QoS is enabled on the network interface in the production server and the DPM 2010 server, the network throttling feature cannot be utilized.

SQL Server Database Recovery: DPM 2010 offers a rapid and reliable recovery of the SQL

server database by integrating a point-time data version with the existing application log, without the need for constant replication and synchronization.

DPM 2010 allows recovery of SQL server databases at the instance level or to a

network folder, and it also allows you to keep both the existing database and

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recovered database (renamed) in the original instance of SQL Server with an option of the database state to be either operational or non-operational.

DPM 2010 offers an option to copy SQL transaction logs between the selected version

of the database and the latest version available for recovery. It will be a smooth recovery operation because any synchronization jobs for the selected recovery item are cancelled while the recovery is in progress.

With enhanced support in DPM 2010, the Self-Service Recovery Tool (SSRT) enables

end users to recover SQL server databases that are backed up by the DPM 2010 server, without any intervention from the DPM 2010 administrator.

For quicker recovery, users can go for SAN-based recovery that requires hardware snapshots. SAN based Recovery is advantageous for the recovery of huge volumes of SQL server databases since it allows faster and more reliable recovery with reduced network bandwidth, bypassing the LAN. This feature is valid only if the hardware snapshot functionality is enabled. In the Dell EqualLogic SAN solution, users can utilize the EqualLogic ASM to perform DPM 2010’s SAN-based recovery, which involves the process of taking the EqualLogic snapshot of the replica volume and the recovery point volume of the DPM 2010 server. For a detailed SAN-based recovery procedure, you can refer to the PS Series Best Practices Deploying DPM 2007 in iSCSI SAN guide, which is applicable for DPM 2010.

SAN HQ: SAN HeadQuarters provides centralized monitoring, historical performance trending,

and event reporting for multiple PS Series groups. Using SAN HeadQuarters, users can quickly be informed of hardware problems, improve performance by identifying performance bottlenecks, and effectively allocate group resources by identifying underutilized resources and monitoring data. SAN HeadQuarters does not disrupt access to group storage or degrade performance. Using SAN HeadQuarters, you can:

Become quickly informed of hardware or performance-related problems. Improve performance by identifying performance obstructions (bottlenecks). Allocate group resources more effectively by identifying underutilized resources. Enable multiple individuals to access and monitor the same performance data.

The following table gives a brief description of the SAN HQ features:

FEATURES DELL EQUALLOGIC SAN HEADQUARTERS

Monitoring and Analytics

Capacity, I/O performance, Network Data, Member Hardware and Configuration, Volumes, Replication, Maximum Theoretical IOPS, IOPS vs Latency, Disk Queue Depth

Reporting

Performance, Capacity Utilization and Trending

Group Configuration with Alerts, Replication Status, Top 10, Host Connections

Ease of Use

Single Sign-on for Launching EqualLogic Group Manager, Point-in-time data views, User defined data ranges, Summary views, Contextual Pop-up views

Reference Configuration

To establish DPM 2010 performance that matches the administrator’s expectation and addresses their

concerns, it is necessary to understand the impact of the DPM 2010’s server primary data operations on

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the production database and on the DPM 2010 server, as well as to understand how these operations consume network resources affecting network performance.

Using the guidelines described in this white paper, the Dell| Database Solution Engineering Team constructed a reference configuration shown in Figure 3. The result and analysis showcase how the DPM 2010 server’s primary data transfer operations, such as initial replica creation, synchronization, and consistency checks, impact Production, backup systems, and network resources. The tests are carried out to determine how the performance of the replica creation will be limited by the speed of the network connection between the DPM 2010 server and the protected computers.

Figure 3. Reference Configuration

Test Case: The following test case scenarios are designed to verify the CPU utilization, Memory

availability, and network performance for replica creation operations and the appropriate disk

allocation method. In the case of Manual Replication, the disk allocation is a Custom Volume that

utilizes the EqualLogic Clone feature. For DPM 2010 server replication (or Automatic Replication), the

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disk allocation is the DPM 2010 storage pool. The tests were carried out on 1g and 10g LAN networks

with an iSCSI network of 10g bandwidth.

Notes:

SQL_Server is the server that hosts the SQL Server 2008 R2 database

DPM_Server is the DPM 2010 server that initiates the primary data operations

Manual Replica is the replication that utilizes the EqualLogic Cloned volume as Custom

Volume

DPM replica is the Automatic replication where the DPM 2010 server does the replication

utilizing the DPM 2010 storage pool

CPU Utilization:

Figure 4: (A) - The following results are for a 1g LAN network with a storage bandwidth of

10g.

Figure 4: (B) - The following results are for a 10g LAN network with a storage bandwidth

of 10g.

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SQL_Server_Manual_Replica_(_Total)\% Processor Time

SQL_Server_DPM_Replica(_Total)\% Processor Time

DPM_Server_Manual_Replica(_Total)\% Processor Time

DPM_Server_DPM_Replica(_Total)\% Processor Time

RAID LAN Network

iSCSI Network

Replica Disk Allocation Protection at Database/Instance

10 1g/10g 10g DPM 2010 server

DPM 2010 storage pool

Database (Instance is applicable)

10 1g/10g 10g Manual Custom Database (Instance N/A)

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Analysis: The % Processor Time is captured to measure the percentage of time that the processor was

busy during the initial replication for a Data Source of a 117GB SQL server database. It was captured

for both the methods of replication – Manual replication and DPM 2010 replication over a 1g/10g LAN

network as shown is Figure 4 (A) and (B). It is observed that in both cases, CPU utilization is a high

average of 20% in the SQL server when compared with the DPM 2010 server, which is an average of 3%.

The impact of the initial replication is more on the SQL server than on the DPM 2010 server. Therefore,

the initial replication of the database should be done when the I/O load is lower on the production

database server.

The value shown in the graph for the DPM 2010 server is minimal because it is for a data load of 117GB,

and no I/O is happening on the SQL server. But this value will significantly change on the DPM 2010

server in the following situations:

When parallel replication is enabled using more custom volumes.

When co-allocating more databases on the disk storage pool.

When multiple DPM 2010 jobs, like synchronization with consistency checks, are run

simultaneously.

As per Microsoft, if more than 95% of CPU usage is shown on the DPM 2010 server for more than

10 minutes, then it is preferred to offload the workload to another DPM 2010 server or to

stagger the synchronization schedule.

Figure 4 (C). CPU Utilization During Synchronization When I/O Is Running on SQL Server

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DPMSERVER_Manual_Replica(_Total)\% Processor Time

SQLSERVER_Manual_Replica(_Total)\% Processor Time

DPMSERVER_DPM_Replica(_Total)\% Processor Time

SQLSERVER_DPM_Replica(_Total)\% Processor Time

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SQLSERVER\Processor(_Total)\% Processor Time

DPMSERVER\Processor(_Total)\% Processor Time

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Analysis: After the initial replica creation, the Quest benchmark factory tool was used to run the I/O on the SQL server of user load 500. After some time, the synchronization with consistency check was performed from the DPM 2010 server. Later, the I/O was stopped on the client. As shown in the preceding Figure 4 (C), the peak rise that is shown in the graph, which went above 25% of CPU utilization, occurs when the I/O load was running on the SQL server and, in parallel, when the DPM 2010 server is synchronizing to check the inconsistencies. The results clearly indicate that the synchronization jobs are CPU intensive.

A few guidelines for synchronization of the SQL application:

The synchronization method should be chosen based on the ability to recover data. If you synchronize only once a day, the maximum loss window is 24 hours. However, if you choose to synchronize every hour, your maximum loss window is 1 hour.

Not all the databases support incremental synchronization. To enable faster recovery time, DPM 2010 will regularly perform an express full backup in place of incremental synchronization.

Because consistency checks affect the performance of both the DPM 2010 server and the protected computer, you should schedule consistency checks for hours when reduced responsiveness of the protected computer has the least impact on your business operations and there is the least amount of network traffic.

Memory Utilization:

Figure 5 (A). The following results are for a 1g LAN network with a storage bandwidth of

10g.

Figure 5 (B). The following results are for a 10g LAN network with a storage bandwidth of

10g.

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SQL_Server_Manual_Replica_Memory\Available MBytes

SQL_Server_DPM_Replica_Memory\Available MBytes

DPM_Server_Manual_Replica-Memory\Available MBytes

DPM_Server_DPM_Replica-Memory\Available MBytes

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Analysis: The Memory Available/Mbytes is captured to measure the memory that is available to

processes running on the specified DPM 2010 server and to determine if the SQL server is impacted.

The Available/MBytes value is the sum of memory assigned to the standby (cached), free, and zero-

paged lists. From Figures 5 (A) and (B), it is observed that the value is >55 megabytes on average. The

DPM 2010 primary data operation job, such as replica creation, affects both memory and CPU usage.

For this test, we have used 8GB of RAM on both the DPM 2010 server and the SQL server. From the

preceding results, Figure 5 (A) is a 1g LAN network and Figure (B) is 10g LAN network. In both cases of

replication methods (Manual Replica or DPM 2010 Server Replica), the memory utilization is more on

the DPM 2010 server when compared to the SQL server. The processes on the DPM 2010 server that can

impact the performance are the DPM 2010 protection agent, the DPM 2010 service, the DPM 2010

Administrator Console, and the DPM 2010 instance of the SQL Server service. If the DPM 2010

Administrator Console (MMC.exe) is always opened, then it can be a significant factor in high memory

usage. Therefore, the console should be closed when it is not in use. Also, the DPM 2010 instance of

the SQL Server service uses a large amount of memory for caching; therefore, it is expected to be

relatively high. This memory usage does not indicate a problem because memory is released when

available memory is low.

Notes:

As per Microsoft, DPM 2010 requires a pagefile size that is 0.2 percent the size of all recovery

point volumes combined, in addition to the recommended size (generally, 1.5 times the

amount of RAM on the computer).

With Volume Shadow Copy Service (VSS) non-paged pool limitation on 32-bit operating systems,

therefore, running DPM 2010 server on a 64-bit operating system (Windows Server 2008 R2) is

an ideal choice that enables you to protect more than 10TB of data.

Network Performance

Figure 6 (A). With a 1g LAN Network for DPM (Automatic) Replica

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DPMSERVER_DPM_Replica\Memory\Available MBytes

SQLSERVER_DPM_Replica\Memory\Available MBytes

DPMSERVER_Manual_Replica\Memory\Available MBytes

SQLSERVER_Manual_Replica\Memory\Available MBytes

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Figure 6 (B). With a 1g LAN Network for Manual Replica

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Figure 6 (C). With a 10g LAN Network for Manual Replica

Figure 6 (D). With a 10g LAN Network for DPM (Automatic) Replica

Analysis: The Network Interface Bytes Total/sec is captured to measure the throughput for the

network interface. This measurement is a combination of inbound and outbound traffic (Bytes Sent/sec

and Bytes Received/sec) of the network interface in Bytes. As shown in the preceding Figure 6 (A) and

(B) of 1g network bandwidth and in the preceding Figure 6 (C) and (D) of 10g network bandwidth, there

is a huge impact in data transfer during Manual Replica or DPM 2010 Replica (Automatic Replica)

creation. In our test validation, we have taken the 117GB database as the data source to be replicated

both manually and automatically. From the preceding results, the data transfer is quick and fast in

Manual Replica as compared to Automatic Replica. But for Manual Replica, we can choose replication

only at the database level and not at the instance level. And, to do manual replication for more than

one database, every database volume should be allocated a Custom Volume and cannot be co-allocated.

However, with Automatic (DPM 2010) Replica, this is not the case. From the preceding Figure 6(B) with

1g bandwidth, the impact of network performance on the SQL server is minimal, when compared to the

DPM 2010 server. Therefore, for large data sets and slow networks (<=1g), the Manual Replica option is

a better choice. And, the DPM 2010 Replica or the Automatic Replica is a good option when collocated

data sources, such as multiple database instances, are to be protected or when smaller sets of too

many databases need to be protected.

If there are more applications using the EqualLogic iSCSI SAN, then Network bandwidth usage throttling enables you to limit the amount of network bandwidth that DPM 2010 can use to create and synchronize replicas. However, network bandwidth usage throttling can lengthen the amount of time each synchronization job takes to complete.

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\\SQLSERVER_custom_vol\10g_Public)\Bytes Total/sec

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A few guidelines to optimize performance:

Offset the start time of synchronization jobs across different protection groups so that they all do not start at the same time.

Run parallel backups of data sources in the same protection group to optimize your network usage.

Reduce the demand on the server's resources by scheduling fewer express full backups; however, doing so can increase data recovery time.

Conclusion Deploying DPM 2010 and Microsoft SQL Server R2 with Dell hardware (PS series 6010 and Dell PE R910)

delivers flexibility, ease-of-management, and scalability. Using a PS Series SAN provides benefits that

include:

Rapid configuration of the DPM 2010 server and the production database environment

Simple and immediate storage pool expansion with features like thin provisioning, flexibility for remote site volume replication, and DPM 2010 initial replica creation

SAN-based recovery solutions with the EqualLogic ASM feature DPM 2010 features seamless integration between disk and tape media and offers ease of management with its intelligent GUI. Co-allocating data sources on the DPM 2010 storage pool allows users to auto-protect multiple SQL server databases at the instance level, so that all new databases within the instance are automatically protected. Using Custom Volumes with the Manual Replica Option and utilizing the EqualLogic Clone feature maximizes the DPM 2010 server’s performance and enables parallel replication, but it restricts you from co-allocating multiple databases on the Custom Volume. To provide continuous data protection for SQL server databases, DPM 2010 performs express full backups and creates recovery points as per scheduled and supported synchronization methods. The inconsistencies between the protected database and replica can be verified by running a consistency check preferably during off-peak hours because it impacts network performance. However, throttling the network by setting maximum limits ensures that network bandwidth is available to other applications as well. With the Self-Service restore capability, SCPM provides a faster and reliable recovery. Based on the preceding reference configuration, the guidelines for disk allocation, Replica creation, and Synchronization are summarized in the following table:

Disk Allocation Initial Replica Creation Method Synchronization Method

Custom Volume

- Creating a Clone Volume using Clone feature as a replica volume.

- Cloning must be done when the I/O load is minimal on the production server.

- Recovery Point Volume must be created for each custom volume.

- Custom Volumes CANNOT be co-allocated.

- Custom Volumes DO NOT support SQL Server

Manual Replication - Can create a Replica from a tape backup or other removable storage media. - Can be done using Custom Volumes and Disk Storage Pool. -In this method, Data must be manually copied to the DPM 2010 Server Replica folder path. - Applicable for large Databases with slow networks (<=1g). -CPU Utilization: The impact of

-For Manual Replica method, the replica must be manually synchronized with a consistency check before scheduled synchronization and recovery point jobs begin. -Because running a consistency check impacts the performance of the DPM 2010 server and Production server, depending on the network load, CPU processing power, and timing, the manual consistency check should be

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Instance level protection. - Enables parallel backups of

data sources that can optimize network usage.

manual Replica is more on SQL server than on DPM server. -Memory Utilization: DPM memory utilization is high than Production Server -Network Utilization: In case of Manual Replica, the impact on LAN network is less

performed only when it is necessary to make the replica consistent with its data source (database).

Disk Storage Pool

- PS storage enables using

thin provisioned volumes as a backend DPM 2010 storage pool.

- Should be a Dynamic disk of twice the size of the protected Data Source (databases).

- Provides instance level protection.

- DPM 2010 adjusts its recommendations for disk allocation to store the replicas and recovery points.

Automatic (DPM) Replication Allow the DPM 2010 server to copy the data from the protected server over the network. This method requires no intervention, but it can take several hours depending on network bandwidth and data size. Good option when collocated data sources, such as multiple database instances, are to be protected or smaller sets of too many databases need to be protected. - CPU Utilization: The impact of manual Replica is more on SQL server than on DPM server. -Memory Utilization: DPM memory utilization is high than Production Server -Network Utilization: In Case of Automatic Replica, the impact on LAN Network is more

For Automatic Replica method, the replica can be synchronized based on scheduled synchronization (incremental). This method is faster than performing a consistency check. But not all databases support incremental synchronization.* An automatic consistency check can be scheduled as a daily task, but because of the processing load impact on the DPM 2010 server and on the Production server, it is scheduled preferably when the network traffic is low.

* Note: DPM 2010 does not support incremental synchronization for master, msdb, and databases that are read-only mode or that use a simple recovery model. They use the Express Full backup. For all other SQL server databases, synchronization transfers a transaction log backup, and recovery points are created for each, incremental synchronization and express full backup. Businesses of all sizes can rely on these best practices to configure Microsoft System Center Data

Protection Manager 2010 to deliver a unified and scalable data protection solution that is cost

effective, secure, and reliable for Windows servers, such as SQL servers.

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References

1. http://www.microsoft.com/systemcenter/en/us/data-protection-manager.aspx

2. http://technet.microsoft.com/en-us/library/ff399519.aspx

3. http://www.equallogic.com/resourcecenter/assetview.aspx?id=5249