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DATABASE TECHNOLOGY1,20070Transactions per secondfor all servers1,000800600400200CPU usage (percent)6968676600 1 2 3 4 5650 1 2 3 4 5Number of serversNumber of replication streamsFigure 7. Workload performance scaling versus number of database serversFigure 9. CPU usage versus number of replication streamsReplication commandsdelivered per second50040030020010000 1 2 3 4 5Number of replication streams• Number of replication commands: Run only the necessarynumber of streams; avoid adding streams if the replicationqueue can be drained in a timely way.Figures 8 and 9 show that, in the pilot study, the replicationthroughput indicator (number of replication commands deliveredper second) increased significantly when the number of replicationstreams was increased up to four streams. Each additional streamadded roughly 1 to 2 percent of CPU usage.Figure 8. Replication throughput versus number of replication streamsthe number of database servers in this pilot study. These resultsdemonstrate that true linear scaling is possible with proper applicationarchitecture. The MSN CSP application is designed to bescaled out for any number of users; currently, millions of usersare supported by the online MSN CSP application.Combining the scale-out management layer and replicationfor enhanced availabilityTogether with the scale-out management layer application, replicationcan help provide excellent data availability. Single-threadedtransactional replication in SQL Server 2000 prevented the MSNCSP application from fully utilizing available server resources. Tohelp overcome that limitation, SQL Server 2005 is designed to supportparallel streaming of replication commands—enabling multiplestreams of 1 to 64 commands to be processed simultaneously. Theoptimal number of streams and how well the performance will scaletypically depend on a variety of factors. Best practices include:• Number of CPUs: Do not use more replication streams thanthe number of CPUs processing those streams to help minimizecontext-switching overhead.• Blocking: Avoid overlapping transactions on tables beingreplicated to help prevent replication streams from blockingone another.• CPU cycles: Be aware that adding a replication streamcreates a task, thus requiring more work and potentiallyincreasing CPU usage.A highly manageable SQL Server scale-out systemIn the example enterprise deployment of the Microsoft MSN CSPapplication, engineers observed linear performance scaling for up tofour database servers. These results were achieved by partitioningand accessing data across an array of industry-standard SMP nodesthat were configured as a federation of Dell PowerEdge servers. Inaddition, the pilot study explored ways to enable high availabilityusing the scale-out management layer application in conjunction withSQL Server transactional replication. The findings discussed in thispilot study demonstrate that Microsoft SQL Server 2005 can be usedto effectively scale out an enterprise database application using DDRto help accommodate data and workload growth.Man Xiong is a software design engineer in test on the Microsoft SQLServer product team. Man has a master’s degree in Computer Science andEngineering from the University of Washington.Brian Goldstein is a lead program manager on the Microsoft SQL Serverproduct team. Brian has a master’s degree in Engineering from the MassachusettsInstitute of Technology and is a Microsoft Certified Systems Engineer.Chris Auger is an enterprise technologist in the Dell Advanced SystemsGroup.FOR MORE INFORMATIONMicrosoft SQL Server 2005:www.microsoft.com/sql/2005/default.asp104DELL POWER SOLUTIONS Reprinted from Dell Power Solutions, August 2005. Copyright © 2005 Dell Inc. All rights reserved. August 2005
DATABASE TECHNOLOGYMigrating an Oracle10g RAC Databasefrom Oracle Cluster File System to Oracle AutomaticStorage Management on Dell/EMC Storage ArraysOracle ® Real Application Clusters (RAC) database file storage options have furthermatured with the release of Oracle 10g software and its Oracle Automatic StorageManagement (ASM) feature. Before ASM, the options available for Oracle RAC databasefile storage were limited to raw devices or the open source Oracle Cluster FileSystem (OCFS). This article compares raw devices and OCFS with the ASM approach,and provides basic steps and best practices for migrating from OCFS to ASM.BY ZAFAR MAHMOOD, UDAY DATTA SHET, AND BHARAT SAJNANIRelated Categories:DatabaseDell/EMC storageFile systemsOracleVisit www.dell.com/powersolutionsfor the complete category index.Oracle Real Application Clusters (RAC) databases requiredirect access to a physical storage system. Before theavailability of Oracle Cluster File System (OCFS) and OracleAutomated Storage Management (ASM), RAC databasesrequired that data files, control files, and redo log files beplaced on raw devices so that they could be shared amongcluster nodes. Database administrators were required tocreate the raw devices, using OS-specific commands, beforebuilding the database. Administrators could bind a rawdevice to an existing block device, such as a disk, and usethe raw device to perform I/O operations with that blockdevice. Such I/O bypasses the Linux ®OS buffer cache thatis normally associated with block devices and can helpeliminate file system overhead. Figure 1 depicts the associationof physical block devices to Oracle database files forthe creation of a RAC seed database.Although raw devices fulfill the requirements fora RAC database, they can be inflexible and difficult forsystem administrators to manage. The unformatted diskpartitions cannot use several key Oracle9i and Oracle 10gfunctions, including the automatic database file extensionand Oracle Managed Files (OMF) features. Eachraw device is bound to only one Oracle database fileand has a fixed size. If the database runs out of spaceon that partition, the database administrator must createanother partition and add another database file to theOracle tablespace. Also, the maximum number of rawdevices—and consequently the maximum number ofOracle database files—that administrators can create onRed Hat ® Enterprise Linux is limited to 255.Introducing Oracle Cluster File SystemThe next evolution of RAC database file storage was theintroduction of Oracle Cluster File System. OCFS is anopen source cluster file system that provides a convenientalternative to raw devices for storing Oracle RACdatabase files on shared storage accessible by all clusternodes. In environments using OCFS, all cluster nodeshave the same view of the Oracle database files and canread and write to the shared storage concurrently.OCFS is designed specifically for RAC databases. Iteliminates the requirement for Oracle database files to belinked to unformatted partitions on logical drives. Administratorscan create OCFS volumes on RAID disks so thatthe volumes span multiple shared disks for redundancyand performance enhancements. Figure 2 depicts theassociation between physical shared storage devices andOracle RAC database files in an OCFS environment.www.dell.com/powersolutions Reprinted from Dell Power Solutions, August 2005. Copyright © 2005 Dell Inc. All rights reserved. DELL POWER SOLUTIONS 105
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Gigabit EthernetMulti-Gigabit Ether
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TABLE OF CONTENTSPOWERSOLUTIONSTHE
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TABLE OF CONTENTSDATABASE TECHNOLOG
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EDITOR’S COMMENTSRelational Bliss
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SYSTEMS MANAGEMENTTake Control with
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SYSTEMS MANAGEMENTInstrumented plat
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SYSTEMS MANAGEMENTinterface (CLI) a
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SYSTEMS MANAGEMENTIntroducing Dell
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SYSTEMS MANAGEMENTA query definitio
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SYSTEMS MANAGEMENTremote agents. Fo
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SYSTEMS MANAGEMENTError code Error
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SYSTEMS MANAGEMENTFigure 3. Wbemtes
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SYSTEMS MANAGEMENTSoftware Change M
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SYSTEMS MANAGEMENTDell UpdatePackag
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SYSTEMS MANAGEMENTFigure 5. Summary
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SYSTEMS MANAGEMENTIT Assistant UI I
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SYSTEMS MANAGEMENTFigure 3. Configu
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SYSTEMS MANAGEMENTConsole, Altiris
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SYSTEMS MANAGEMENTDeploying Server
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SYSTEMS MANAGEMENTAdvancing the Upd
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SYSTEMS MANAGEMENTallows administra
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SYSTEMS MANAGEMENTTime-Savings Vali
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SYSTEMS MANAGEMENTBENEFITS OF ALTIR
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SYSTEMS MANAGEMENTLANDesk Server Ma
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SYSTEMS MANAGEMENT• SEL event cre
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SYSTEMS MANAGEMENTAdministrators ca
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SYSTEMS MANAGEMENTUsing the DRAC 4
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Page 74 and 75: BUSINESS CONTINUITYe-mail systems u
Page 76 and 77: BUSINESS CONTINUITYGalaxy and Backu
Page 78 and 79: STORAGE TECHNOLOGYWhen migrating fr
Page 80 and 81: STORAGE TECHNOLOGYwhich can lead to
Page 82 and 83: STORAGE TECHNOLOGYChannel ports; al
Page 84 and 85: STORAGE TECHNOLOGYMaximum zone sets
Page 86 and 87: STORAGE TECHNOLOGYbenefits includin
Page 88 and 89: STORAGE TECHNOLOGYmemory manager wa
Page 90 and 91: STORAGE TECHNOLOGYLink-Level Error
Page 92 and 93: STORAGE TECHNOLOGYThe extended link
Page 94 and 95: STORAGE TECHNOLOGYMigrating from De
Page 96 and 97: STORAGE TECHNOLOGYFigure 3. Managin
Page 98 and 99: DATABASE TECHNOLOGYFast, Flexible C
Page 100 and 101: DATABASE TECHNOLOGYScaling Out SQL
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Page 108 and 109: DATABASE TECHNOLOGYAdvantages of OC
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Page 114 and 115: SYSTEM ARCHITECTUREImproving Fault
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