Databases Solutions Engineering. Deploying Microsoft SQL Server with Dell PowerVault MD1120 Storage Array with Database Mirroring

Transcription

1 DELL Reference Architecture Guide Deploying Microsoft SQL Server with Dell PowerVault MD1120 Storage Array with Database Mirroring A Dell Technical White Paper Mirroring Databases Solutions Engineering By Anthony Fernandez and Madhulika Gaur Dell Product Group July

2 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. All rights reserved. Reproduction in any manner whatsoever without the express written permission of Dell, Inc. is strictly forbidden. For more information, contact Dell. Intel and Xeon are registered trademarks of Intel Corporation in the U.S. and other countries; Microsoft, SQL Server, Windows, and Windows Server are either trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. 2

3 CONTENTS ABSTRACT... 4 INTRODUCTION... 4 EXECUTIVE SUMMARY... 4 ARCHITECTURE OVERVIEW... 4 DELL POWERVAULT MD1120 (SAS) STORAGE... 5 DELL POWEREDGE PE 2950 III ES... 6 DESIGN CONSIDERATIONS... 7 PERC6E RAID CONTROLLER CONSIDERATIONS... 7 DATA PROTECTION SOLUTION FOR MD1120 WITH SQL SERVER MIRRORING... 8 DISK VOLUME LAYOUT GUIDELINES... 8 DATA VOLUMES... 8 LOG VOLUMES... 8 TEMPDB VOLUMES... 8 EXAMPLES OF DISK CONFIGURATIONS... 9 SOLUTION COMPONENTS REFERENCES APPENDIX A: CONFIGURE STORAGE CONNECTIONS APPENDIX B: DISK CONSIDERATIONS

4 Abstract This white paper provides a reference design architectural overview and configuration guidelines for deploying Microsoft SQL Server 2005 on Dell PowerEdge servers with Dell MD1120 storage using database mirroring to provide a low-cost solution with high availability. Using proven best practices, this technical report summarizes those recommendations to provide a robust starting point to build a high-performance scalable and reliable database platform. Introduction This white paper focuses on providing a scalable design for small-to-medium enterprise level database solutions running on Microsoft SQL Server 2005 and Dell MD1120 Storage. Dell PowerEdge servers are an exceptional choice to deliver outstanding price and performance and to deploy highly reliable databases. Using a building-block approach, customers can build and scale their applications on Dell hardware at an impressively low cost as their need grows. Dell PowerVault MD1120 provides an ideal Direct Attached Storage (DAS) solution for small to medium enterprises for a very low cost and complexity for Fibre Channel SAN solutions, while providing high performance for database workloads. This Reference Architecture Guide is intended to help IT professionals design and configure Microsoft SQL Server 2005 database solutions using Dell servers and Dell PowerVault storage that apply best practices derived from laboratory and real-world experiences. The purpose of this whitepaper is to provide a detailed view of the benefits of a SQL Server deployment on a Dell PowerVault DAS storage array. It will provide a summary and references to all the best practices to configure Dell servers and Dell PowerVault storage hardware and software for an optimal solution deployment. This Dell Deployment Guidance white paper documents the results from engineering testing, captures details of the hardware and software tested, and provides tips and hints for deploying and operating the solution. Additional Dell Deployment Guidance white papers for SQL Server are delivered online at Executive Summary Following Microsoft and Dell best-practice guidelines, we describe the design considerations process we used to deploy and provide tips to achieve best performance. These design considerations are divided into the following categories. Storage Server SQL Server considerations Architecture Overview This section lists the components required to deploy a high-performance (DAS) solution for SQL Server databases. An architectural overview of the Dell Solution for SQL Server 2005 is shown in Figure 1 below, comprised of the following components: 4

5 Two Dell PowerEdge PE 2950 III Energy Smart (ES) servers Two PERC6E RAID controllers Six Dell PowerVault MD1120 SAS storage enclosures Principal SQL2005 SQL2005 Mirror Dell PE2950III ES Dell PE2950III ES Dell PowerVault MD1120 Dell PowerVault MD1120 Figure 1 Detail Architectural Overview of Dell SQL Server 2005 Configuration on MD1120 Dell PowerVault MD1120 (SAS) Storage The MD1120 is a Just a Bunch of Disks (JBOD) array that offers a low-cost, high-performance solution to implement a single-node SQL Server database. With a total of 24 15K or 10K drives per array, the new 2.5 SAS drives fit into a 2U chassis and have better power efficiency than their 3.5 counterparts. If the goal is performance by spreading I/O with over large number of hard drives, the MD1120 allows up to 144 hard drives daisy chained to a single PERC6E controller. (See Appendix A for a cabling diagram.) Some of the general categories are summarized in the following table: Table 1: Storage Overview Cost Reliability and Availability Storage Overview Offers a low cost DAS solution for price sensitive deployments. Equipped with dual Enclosure Management Module (EMM). Second EMM is used when operating in split-mode or in unified-mode with 5

6 (Redundancy) limited failover capabilities (see Note below). Includes redundant power supplies and cooling fans. Performance 24 SAS 10K or 15K hard drives per array. 12Gbps SAS connector to the host. Scalability Easy to daisy chain up to six MD1120 arrays to provide scalability up to 144 drives per PERC6. Data Protection Raid 0, 1, 5, 6, 10, 50 and 60. Ease of Deployment Easy to configure Virtual Disks through BIOS or Dell OpenManage and Management Server Administrator (OMSA). Service Level Implement RAID level for data protection and data separation through Commitments virtual disks; and with application level disaster recovery strategies, organizations can meet their requirements to satisfy various applications, while maintaining simplicity and low cost of ownership. Table 2 summarizes the differences between MD1120 and MD3000 storage arrays. Table 2: Differences Between MD1120 and MD3000 Type JBOD Unit RAID controller is on the host RBOD Unit RAID is in the storage module Hard Drives 24 drives 15 drives Maximum configuration per port (Expanded with upto 2 MD1000) Enclosure size 2U enclosure 3U enclosure Hard Drives size Clustering support No Yes High Availability Configuration Limited (see Note below) Note: From a high-availability perspective, the Enclosure Management Module (EMM) on the MD1120 does not offer active/active mode, since the controllers reside on the PCIe bus on the host. When cabled to both EMMs from a single controller, if the primary EMM fails, the second takes over; however the host needs to reboot in order to regain access to the disks. This means that in order to offer a high-available solution, it is imperative that other solutions are coupled at the software layer to provide protection against failures. This reference architecture will use SQL Server mirroring to attain the desired levels of high availability. Dell PowerEdge PE 2950 III ES Dell PowerEdge servers are designed to deliver the highest performance for critical enterprise applications like database, messaging, web services, and infrastructure applications. As proprietary systems are increasingly replaced by industry-standard systems, applications like databases, high performance computing clusters and messaging systems can take advantage of the performance and scalability of the PowerEdge servers. We choose the PE2950III ES (Energy Smart) server for this reference configuration for two reasons. 1) We realize that small to medium database deployments do not run at maximum capacity around the clock. In a typical environment during working hours, users log in to perform transactions, while during non-peak hours, DBAs schedule batch processing and reporting. The PE2950III ES with their energy efficient Quad Core processors offer the performance required with maintained high level of processing while keeping power Yes 6

7 consumption low. This is an ideal server to implement a SQL Server database Mirror solution. 2) The PE2950III ES supports up to eight internal 2.5 hard drives. The same hard drives can be used in the MD1120. Two hard drives can be allocated for OS in RAID 1. The extra six hard drives allow the flexibility to do local temporary backups, database logs, or system databases such as master, model, and msdb. If you choose to keep log files on internal hard drives, keep them purely for log files. Since they are sequential in nature, this helps minimize random access. Transaction throughput is limited by the logs. Table 3: PowerEdge 2950III ES Features Features PowerEdge 2950 III ES as tested PowerEdge 2950III ES Maximum Configuration Processor One Quad Core Intel XEON L5410 Two Quad Core Intel XEON L5420 series 2.33GHz 2x6M cache 2.50GHz 2x6M cache 50W Memory Eight GB RAM Eight RAM slots - offering up to 64GB Front Side Bus 1333MHz I/O Slots Two PCIe x8 slots One PCIe x4 slot Internal Storage Eight hot-plug SAS (2.5) Drives Eight hot-plug SAS (2.5) Drives Internal RAID Controller Networking Processor PERC6i for R0 and R1 with cache and battery backup Dual-integrated LOMs Broadcom Gigabit 5708 with optional TOE license key One Quad Core Intel XEON L GHz 2x6M cache 50W PERC6i for R0 and R1 with cache and battery backup Dual integrated LOMs Broadcom Gigabit 5708 with optional TOE license key Two Quad Core Intel XEON L GHz 2x6M cache 50W Design Considerations The goal of this reference architecture is to show how customers with small-to-medium needs can implement a robust DAS database deployment to meet their performance and high-availability requirements. The following sections explain these recommendations in the context of the various subsystems that are integral to the Dell Solution for SQL Server. PERC6E RAID Controller Considerations PERC6E is a high performance PCIe RAID controller with two x4 wide SAS ports, each capable of 12Gbps throughput by leveraging 3Gbps protocol. Place PERC6E RAID controllers on separate PCIe buses Depending on the workload the total number of controllers in the system would play an important role. If the workload uses large I/O operations such as an OLAP workload with large sequential reads or bulk operations (large sequential writes), it could saturate the x4 wide SAS port on the controller. In this case, instead of daisy chaining a second MD1120, it would be best to connect it directly to the second x4 wide SAS port on the controller. In addition, a second PERC6E can be installed on the second PCIe x8 riser slot for added throughput. If the workload uses small I/O operations such as an OLTP with small random reads and writes, the bottleneck will be the number of disks available to serve the I/Os and not the controller. In this case, scaling out by daisy chaining the enclosures is recommended. 7

8 Both of the above mentioned techniques can be implemented together to drive complex workloads. See Appendix A for a complete list of all cabling permutations. Data Protection Solution for MD1120 with SQL Server Mirroring Since the MD1120 has limited failover capabilities, in order to mitigate one single point of failure, it is crucial to implement a business continuity strategy around this configuration. The SQL Server 2005 Mirroring feature offers the continuity to alleviate the single point of failure without costly hardware or software solutions. Customers can benefit from this feature without the added cost of purchasing Enterprise Edition. SQL Server Standard Edition offers this feature in Safety Mode or synchronous mode. This mode offers total protection. It guarantees that transactions are written to the mirror server logs before they are considered complete on the primary server. In case of failure in the primary server, no loss of data will occur since the mirrored server is up to date. Mirroring also allows for the flexibility to perform planned maintenance without incurring downtime. Disk Volume Layout Guidelines It is highly recommended that the database data,log files and TempDB do not share the same physical spindles. This precaution prevents the loss of data in case of multiple drive failures, and it improves performance. Data Volumes Microsoft guidelines recommend that the number of virtual disks required for data should be equal to the number of CPU sockets. This can be achieved with a single array. See the following example in Figure 2. However, within in a single PERC6E you can expand up to six arrays and support RAID groups of up to 16 spindles. This yields a minimum of nine disk groups. Windows Stripe Volume can be used to create a stripe volume over these nine disk groups and present them to the operating system as a single disk group. The downside with this strategy is that it introduces another layer of abstraction, which could potentially affect performance. In addition, it can make it difficult to identify performance issues at the storage subsystem. It is recommended that users maintain a simple design and understand the I/O patterns for each disk group. Note that when implementing SQL Server mirroring, it is required that the database contains an identical setup. This means that the mirror database should be named exactly like the principal and contains the same number of data files and drive information.. Log Volumes In order to gain database scalability, make sure that database log files reside in a RAID group with sufficient spindles. Scalability of the database depends on the transaction throughput of database log files. Tempdb Volumes When the SQL Server database is installed, the TempDB is created using a single data file on server internal drives. Adding additional TempDB data files can help avoid latch contention on allocation pages and help solve I/O performance issues. And, where possible, it is preferred to place these files on dedicated spindles. As a result, it is recommended to separate tempdb into a number of equally-sized files that corresponds with the number of cores. Similarly, the AUTO GROW option is enabled for TempDB files. Expanding TempDB too frequently can lead to performance degradation. For optimal performance, pre-allocate the TempDB space with a size large enough to accommodate the expected workload, and set the file 8

9 growth increment large enough to minimize TempDB expansions. The recommended FILEGROWTH increment of 10% 1 is generally sufficient. For additional best practices for Tempdb, please refer to Deployment Guidance Whitepapers section on Examples of Disk Configurations Figure 2 illustrates a simple disk group configuration that separates transaction logs and data onto distinct sets of physical disks. The maximum number of hard drives in a virtual disk group is 16. L:\ R:\ LOGS RAID 1/0 DATA RAID 1/0 Hot Spare Figure 2 Disk Configuration Separating Transaction Logs and Data If tempdb requires more spindles, especially in OLAP environments where heavy use of tempdb for sorts and hash joins, it is best practice to create a separate disk group on the array. In the following figure, assuming that it is an OLAP environment, the transaction logs are not suffering from heavy use. Hence, they could be located on the six spindles on the internal RAID controller. T:\ G:\ TEMPDB RAID 1/0 DATA RAID 1/0 Hot Spare Figure 3 Disk Configuration Separating Tempdb, Data, and Hot Spares 1 Working with TempDB in SQL Server 2005, Wei Xiao, Matt Hink, Mirek, Sunil Agarwal, Microsoft TechNet, June 26, 2006, 9

10 Conclusion This paper summarizes a configuration to implement a high-availability solution using SQL Server 2005 Mirroring on Dell PowerEdge servers and Dell PowerVault MD1120 DAS storage enclosures. The solution proposed in this paper provides a great balance between cost and data availability. Small-to-medium customers can implement a highly scalable solution for DAS storage without sacrificing performance and at a fraction of the cost of more complex solutions like Fibre Channel SANs. PowerEdge 2950 III ES offers the performance to handle large transaction loads while maintaining low energy consumption. With SQL server mirroring on Standard Edition, customers can rest assured their data is protected and readily available. This white paper provides a series of guidelines and best practices from Microsoft and Dell recommendations. Specific guidelines for this reference solution are listed in the appendices. For additional guidance on best practices, please refer to the Deployment Guidance Whitepapers section on Solution Components The following table summarizes the components, drivers, and firmware used during testing for this reference configuration. For the latest drivers please visit Table 4: Solution Components Solution Components Model BIOS ESM/BMC Firmware PowerEdge Servers PE2950 III ES Internal RAID Controller Adapter PERC 6/i Firmware version = ; Driver version = SAS Backplane Firmware Firmware version = External RAID Controller Adapter PERC6E Firmware version = ; Driver version = Integrated Network Adapters Broadcom NetXtreme II 5708 Gigabit Ethernet Driver Driver version = (A01), VBD = LOM Firmware = (A01) Ethernet Teaming Driver Driver version = SAS Storage Dell PowerVault Storage MD1120 RDBMS Microsoft SQL 2005 x64 Standard Edition SP2 Operating systems Microsoft Windows Server 2003 R2 with SP2 Standard x64 Edition 10

11 References Advanced Configuration Options in Microsoft SQL Server 2005, Ananda Sankaran and Shabana M., Dell PowerSolutions August Storage Top 10 Best Practices, Microsoft TechNet, October 17, Physical Database Storage Design, Kathy Lu, Lewis Bruck, Microsoft TechNet, February 12, Clustered SQL Server do's, don'ts, and basic warnings, Revision 13.1, September 14, Working with TempDB in SQL Server 2005, Wei Xiao, Matt Hink, Mirek, Sunil Agarwal, Microsoft TechNet, June 26, Microsoft SQL Server I/O subsystem requirements for the tempdb database Disk performance may be slower than expected when you use multiple disks in Windows Server 2003, in Windows XP, and in Windows 2000, Revision 1.1, October 11, SQL Server 2000 I/O Basics, Bob Dorr, TechNet, January 21, SQL Server I/O Basics, Chapter 2, July 19, Predeployment I/O Best Practices, Mike Ruthruff, June 5, Diskpart Alignment 11

12 APPENDIX A: Configure Storage Connections Figure 1 illustrates the interconnection of two PowerEdge servers hosting SQL Server 2005 and an MD1120 storage system where the database resides. This configuration allows an affordable DAS solution with high availability and scalability. Enclosure Modes The MD1120 can be configured in Unified Mode and Split mode. Unified Mode allows the Enclosure Management Module (EMM) to control all available hard drives in the enclosure. In split mode, each EMM controls half the back plane or total of 12 hard drives. In order to convert from one mode to the other, adjust the switch on the front of the enclosure and power-cycle the array. Two PowerEdge Servers SQL Mirror with one MD1120 Split-Mode The following image shows from each server directly attached to each EMM on the MD1120 with one PERC6E RAID controller installed on each server. Only one port is cabled to each individual EMM. Split-mode allows each controller full control of the hard drives it houses. Both EMMs are active at the same time. Each EMM has access to 12 hard drives. Note: Daisy chaining more enclosures for expansion in split-mode is not supported. Figure 1 - Cabling a Direct Attached MD1120 Storage Array in Split-Mode Two PowerEdge Servers Unified-Mode This configuration allows each power edge server to host the primary and mirror database in its own chassis in unified-mode. In unified-mode, the EMM controls the entire array. This configuration allows for expansion by daisy chaining up to three enclosures. Figure 2 - Cabling a Direct Attached MD1120 Storage Array in Unified Mode Two PowerEdge Servers Expanding enclosures Each 3Gbps x4 wide SAS port can support up to three MD1120 for OLTP type workloads comprised of small I/O random reads and writes. 12

13 Figure 3 - Cabling a Direct Attached MD1120 Storage Array in Unified Mode Two PowerEdge Servers High Throughput If your application requires high throughput (MB/s), it is recommended to connect to second port instead of daisy chaining to better take advantage of each 3Gbps x4 wide SAS link port. Figure 4 High Throughput Configuration NOTE: In certain circumstances, where the storage system is expected to handle an extremely high throughput, it may prove beneficial to further separate traffic by adding a second PERC controller. In such a configuration, each PERC controller will be located on a separate bus, and will drive I/O to a single MD1120. Internal Hard Drives for Added Capacity Hard Drive 0 and 1 used for Operating System in a RAID 1 configuration. Total capacity 67.7GB. Hard Drives 2 7 can be implemented as a 6 spindle RAID 1/0 disk group that can be used for additional capacity and performance. Depending on the purpose designated, they could be 15K or 10K speed. 13

14 APPENDIX B: Disk Considerations When creating partitions, always align=128 The MD1120 has a default stripe size of 128KB. It is recommended to keep this value default. Rule of thumb: always align the partition to the underlying storage stripe size. Most vendors use multiples of 64KB. Using diskpart, for each virtual disk create the partition using this command: create partition primary align=128 Choosing RAID Level Choosing RAID level for database files, logs, and tempdb is an important consideration for performance and fault tolerance required for the organization. Depending on the workload, service level agreements, and personnel available, various strategies can be implemented to define the RAID configuration for each virtual disk. Assumptions; OLTP workload (8KB) IOs random read/writes. OLAP workload (1024KB) IOs read sequential. Case scenarios: Refer to Table 1: Table 1: Disk and RAID Design Considerations Disk Rotational Higher rpm disks offer faster access times and better transfer times Speed than disks with slower rotational speeds. Lower rpm disks generally provide additional per-spindle capacity vs. disks with faster rotational speeds. 15k disks are recommended for Transaction Processing (OLTP) environments where small random I/Os make their performance characteristics desirable. Higher-capacity drives may be well-suited for workloads with large sequential I/O patterns, such as Analytical Processing (OLAP), Data RAID Levels for Database Volumes Hot Spare Strategy Warehouses, or Decision Support Systems (DSS). OLTP max redundancy; RAID 10 with 2 spares. OLTP max performance; RAID 10 no spares. OLAP max capacity; RAID 5 OLAP max redundancy; RAID 6 OLAP performance; RAID 50 Hot spare disks allow automatic re-builds of data to re-establish RAID data protection in the event of a disk failure. Spares are recommended for all storage arrays that provide production enterprise applications. In test and development environments, the extra capacity made available may outweigh the risk of data loss that is associated with a second failure occurring within a degraded RAID set. Distribute I/O by Adding Arrays In order to achieve latency requirements, by daisy chaining up to three arrays on a channel, six total arrays per PERC6E controller, offers 144 hard drives in which to distribute database files for maximum performance. Hot spares Can Be Set in Three modes When choosing to add hot spares, PERC6 supports various modes that can be implemented depending on the design, number of arrays, and fault tolerance required. Global as long as it has enough capacity Dedicated assigned the hot spare to a specified disk group Affinity option is a local hot spare for the entire array 14