Oracle ASM Training

1. Oracle ASM TrainingOracle ASM TrainingByVally CardozaJim Stolzenfeld

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21. Oracle 10G ASM

22. AgendaDatabase ConceptsASMLibASMASM Best PracticesASM ManagementASM TroubleshootingMigrating database to ASMOrion Tool11g ASM new featuresQ/A

23. Database ConceptsDatabase ConceptsDatabase ArchitectureStorage Architecture (Logical)Storage Architecture (Physical)Storage Requirements

24. Database ArchitectureCollection of system elementsShared MemoryConcurrency is maintained by locks/latchesMessage passing between processesDBWR (Database writer)LGWR (Log Writer)

25. Database ArchitectureUser processUser processUser processServer processServer processServer processProcess monitor processBuffer poolShared memoryLock Manager processQuery plan cacheLog bufferLock tableDatabase Writer processLog Writer processCheckpoint process Log disks data disksdata disks

26. Storage (Logical)TablespacesSegmentsData segmentIndex segmentTemporary segmentRollback segmentExtentsOracle data blocks

27. Storage (Physical) Database System Tablespace Data TablespaceTableTableTableIndexTableTableIndexIndexIndexIndexTableIndexTable DBFILE1 DBFILE3 DBFILE2 Drive 1 Drive 2

28. File TypesFile Types

29. Oracle binaries ( ASM and RDBMS home)

30. Database files

31. Datafiles

32. Control files

33. Redo log files

34. Archived log files

35. Backup files

36. Database external files – bfiles, external tables

37. Application related files

38. Clusterware files – OCR (Oracle Cluster Registry) and Vote disks

39. Server Initialization files ( SPFILEs)Storage RequirementsLocal Filesystems /NAS/NFS

40. Oracle binaries

42. Database files

43. SPFILES(RDBMS & ASM)

44. Cluster FS (OCFS)

45. Oracle binaries

47. Oracle Clusterware devices

48. Database files

49. SPFiles (RDBMS & ASM)Raw/Block devicesDatabase filesSPFILES (RDBMS & ASM)Oracle Clusterware devicesASMDatabase filesSPFILES (RDBMS)

50. ASMWhat is ASMVolume Manager and file system built into Oracle KernelFile system with raw disk performanceEliminates need for third-party volume manager and file system for Oracle datafilesUsable for non-RAC and RAC databases alikeCan be run over LVM (not recommended)

51. ASMLIBAn API developed by Oracle to:Simplify the operating system to database interfaceExploits the capabilities and strengths of vendors’ storage arrayAlternative interface for the ASM enabled kernel to identify and access block devices3rd party vendors would write ASMLIB libraries for their arrayOracle distributes an Oracle ASMLIB for Linux only (free add-on to ASM)

52. ASMLIBReduced OverheadGlobally manages all disk file descriptors for ASM [RAC]Disk Management and DiscoveryAutomatic disk discoveryASM_DISKSTRING need not be set I ASM detects ASMLIB or set to ‘ORCL:*’Device name persistence across all nodes in a clusterAutomatic ASM disk namingObviates the need for raw devicesI/O ProcessingOne call to ASMLIB can submit & reap multiple I/O’s, reducing the number of calls to OS – context switches.Performs async I/Os via internal calls

53. ASMLIB Installation & ConfConsists of three rpms:oracleasm-support-2.0.1-1.i386.rpmoracleasmlib-2.0.1-1.i386.rpmoracleasm-2.6.9-34.ELsmp-2.0.1-1.i686.rpmDownload the ASMLib software from the OTN website

54. ASMLIB Installation & ConfInstall the packages as the root user# rpm –Uvh oracleasm-support-2.0.1-1.i386.rpm \ oracleasmlib-2.0.1-1.i386.rpm \ oracleasm-2.6.9-34.ELsmp-2.0.1-1.i686.rpm

55. ASMLIB Installation & ConfConfiguring the Oracle ASM library driver. It will configure the on-boot properties for it.#/etc/init.d/oracleasm configureResponse requiredDefault userDefault groupStart Oracle ASM library on bootFix permissions of Oracle ASM disks on boot

56. ASMLIB Installation & ConfOnce ASMLIB is installed and configured. Once ASM is restarted, ASM will dynamically discover that ASMLIB is loadedAll disk discovery and IO calls are handled through ASMLIBAfter ASM initialization you’ll see the following message in the ASM log:Loaded ASM library – Generic Linux version 1.0.0 library for asmlib interface

57. ASMLIB - Creating disksOnce the kernel module is loaded, stamp (or label) the partitions created earlier as ASM disks#/etc/init.d/oracleasmcreatedisk VOL1 /dev/sdb1 ( Marking disk “/dev/sdb1” as an ASM diskIf RAC installation, on the other nodes#/etc/init.d/oracleasm scandisks# /etc/init.d/oracleasmlistdisks displays VOL1

58. Lab 1 : Configuration of devices for ASMLab 2 : Install and Configure ASMLIB

59. I/O DistributionASM implements Stripe and Mirror Everything( SAME)

60. Spreads file AUs evenly across disks in Disk Group

61. Evenly spreads space usage and I/O across disks

62. Removes need for manual tuning

63. Allows online storage reconfiguration

64. Since ASM distributes extents evenly, there are no hot spotsASM Placement in the Storage Stack Applications DatabaseASMOperating SystemStorage System

65. ASM Operational Stack Tables TablesTablespaceTablespace Files FilesASM File System File System Logical Vol Logical Vol Disks Disks Group Networked Storage (SAN , NAS)

66. Storage and ASM administrationSYS Admin RolePre-InstallationCreate LUNsSet Ownership and permissions to Oracle userASM Admin RoleInstallationOracle Universal Installer (OUI)Conf AssistantsCreate disk groupsNormal OperationMonitor capacity and availabilityProvision capacity

67. ASM Reduces Mgmt ComplexityEliminatesLVM mgmt for Oracle DB File system mgmt for Oracle DBCluster FS and RAW mgmtFile name mgmtReshuffling, reallocating moving datafilesI/O performance tuningReduce significantlyLUN mgmt (larger LUNs)Less frequent DBA and sys admin interactionManual error prone tasksTroubleshootingExpanding Capacity

68. Traditional LVM/FS vs ASM Add CapacityLVM/FSAdd Disk to O/SCreate volume(s) with Volume ManagerCreate File System over volumeFigure out data to move to new diskMove data to new filesRename files in databaseRe-tune I/OASMAdd Disk to O/SAdd Disk to a disk group

69. ASM Process Architecture DB InstanceNon-RAC Database ASM Instance Server Pool of StorageDisk Group Disk Group

70. ASM ArchitectureStorage and Data ObjectsAllocation Units

71. ASM Disks

72. Disk Groups

73. External redundancy

74. ASM redundancy

75. ASM Files

76. Extent Maps

77. RebalanceAllocation UnitsASM Disks are divided into Allocation UnitsDefault allocation unit size is 1MBIn 11g – configurable at diskgroup creation1 MB Allocation Units small enough to be cached by database and large enough for efficient sequential accessFiles are a collection of Allocation UnitsAnalogous to extents in filesystems

78. ASM DiskObject of persistent storage for a Disk Group

79. Accessed through normal OS interfaces

80. Needs to be read/write accessible by Oracle user

81. Accessible to all nodes in a cluster

82. May have different names on different nodes

83. Path names not stored on disk

84. Object that is protected using ASM redundancy

85. Files evenly distributed across disks in a Disk groupStriping GranularityASM separates striping for load balance and striping for latencyCoarse grained striping concatenates virtual extentsFine grain striping puts 128K stripe units across groups of 8 virtual extents for latency

86. Disk Header InfoDisk Header defines ASM DiskBlock zero of every ASM DiskASM Disk name and numberTime stamp of creationHouses ASM metadataFile directoryAllocation table and Free space table

87. Disk DiscoveryASM InstanceHas a bootstrap file called init.ora/spfile.oraASM_DISKSTRING=/dev/rdsk/*ASM_DISKGROUP=‘DATA’,’FRA’Display discovered disksSelect name, path from V$asm_disk; asmcmd>lsdsk

88. ASM Diskgroup OverviewHighest level object managed by ASMA collection of ASM disksSelf-describing independent of media nameA file is allocated within a disk groupMultiple databases share multiple disk groups

89. ASM Diskgroup TypesDisk GroupsExternal RedundancyRedundancy Managed by external means; e.g; intelligent storage arrayA collection of ASM disksASM RedundancyRedundancy managed and maintained by ASMNormal – mirroringHigh – Triple mirroring

90. ASM Diskgroup SetupA walkthrough configuration of a diskgroupPresent LUNs to hostEnsure correct disk permission so that ASM disk discovery will find the provisioned LUNs.Create diskgroup using the required number of disks:SQL> create diskgroup DATA external redundancy disks ‘/dev/sda1’,’/dev/sda2’;

91. External Redundancy12543Five data extent file

92. External Redundancy12534Five data extent file and One MB fine grained file

93. ASM Failure GroupsA Disk Group is partitioned into two or more Failure Groups

94. A Failure Group is a set of disks sharing a common resource whose failure needs to be tolerated

95. Redundant copies of extents are stored in separate Failure Groups

96. Failure Groups are specified by DBAs or automatically by ASM

97. Hardware dictates Failure Group boundariesASM Failure GroupsServerController 2Controller 1Failure Group 1Failure Group 2Disk Groups

98. Normal RedundancyDisk ADisk FDisk EDisk BDisk HDisk GDisk CDisk DFailure Group 2Failure Group 1Empty Disk Groups

99. Normal RedundancyDisk ADisk FDisk EDisk B14154Disk HDisk GDisk CDisk D35322Failure Group 2Failure Group 1Five MB normal redundancy filePrimary extents in redSecondary extents in green

100. Disk FailureDisk ADisk FDisk EDisk B14154Disk HDisk GDisk CDisk D35322Failure Group 2Failure Group 1Disk H Fails

101. Disk FailureDisk ADisk FDisk EDisk B141543Disk HDisk GDisk CDisk D353252Failure Group 2Failure Group 1Reconstruct Redundancy

102. Disk FailureDisk ADisk FDisk EDisk B141543Disk GDisk CDisk D3252Failure Group 2Failure Group 1Drop Disk

103. ASM FileASM File creationASM Instance is registered with CSS (Cluster Synchronizing Service) Database Process connects directly to ASM instance getting information from CSSDatabase requests file creation and blocks for replyASM foreground creates Continuing Operation Directory (COD) entry and allocates space for new file across all disksASMB receives extent map for new file

104. ASM FileASM File creation (cont’d)Database process initializes file contentsDatabase process requests commit of file createASM foreground clears COD(Continuing Operation Directory) and marks file createdASMB message to delete extent map closing fileDatabase process logs out of ASM

105. ASM FileASM File OpenDatabase Process allocates a connection slaveOpen request sent to slave and on to ASM foregroundASM foreground finds file and sends extent map to ASMBSlave receives successful open and returns it to the database process

106. Extent MapDisk AExtent Map ASM File14Disk B2Disk C3 File Address Space

107. ASM RebalanceStorage reconfiguration ( add/drop/failure) leads to a need to rebalance

108. Rebalance is done automatically while Disk Group is online and only one extent is locked at a time

109. ASM files are equally spread across all disks in a Disk Group

110. Disk add => Share of file extents from all currently mounted disks are moved to a new disk

111. Disk drop => File extents on dropped disk evenly moved to remaining disksLab 3 : Creating ASM Instance and managing ASM Disk Groups

112. ASM Best PracticesASM Installation

113. Install ASM in a separate ORACLE_HOME than the database ORACLE_HOME

114. Provides higher availability and manageability

115. Allows independent upgrades of the database and ASM

116. De-installation of database software can be performed without impacting the ASM instance

117. Disk Best Practices

118. If using hardware RAID, make sure LUN stripe size is as close to 1mb as possible

119. Use OS disk labels when possible

120. Prevents accidental user overwrites of disks

121. Easier management of disks

122. Make sure the disk (partition) starts at 1MB a boundary, to ensure proper I/O alignment

123. With 10.2, one can use block devices for e.g. use /dev/sda1 instead of /dev/raw/raw1ASM Best PracticesDisk Best PracticesMake sure disks span multiple backend disk adaptersImplement multiple access paths to the storage array using two or more HBAs or initiatorsDeploy multi-pathing software over these multiple HBAs to provide I/O load balancing and failover capabilities -- Metalink note 294869.1 Disk group Best PracticesCreate two diskgroups, one for database area and another for flash recovery area (no need to separate data from indexes)Create diskgroups using large number of similar type diskssame size same performance characteristicsTo minimize search overhead, perform all required mount operations in a single mount commandThe size of FRA diskgroup will depend on what is stored and how much is retained. The size is driven by recovery time objectives

124. ASM Best PracticesDisk group Best PracticesUse ASM external redundancy when using high-end storage arraysUse ASM redundancy for low-end(modular) or JBOD storage array systemsUse failure groups with ASM redundancy,Determine what failure components your are protecting yourself from.Rebalance Best PracticesIf adding or removing multiple disks, make the change in a single rebalance operationThis coalesces rebalance operations and reduces overheadMake sure enough CPU and IO resources are available for rebalance operationUse ASM power level of 5Check to make sure a diskgroup is not left in a “unbalanced” state

125. ASM Best PracticesDatabase-ASM Best PracticesUse Oracle Management File (OMF)Easier Oracle file managementReduces user file management errorsEnforcement of OFA standardsAutomatic deletion of ASM files when database files are droppedTo use OMF set:db_recovery_file_dest=‘+FLASH’db_create_file_dest=‘+DATA’The following recommendations for database SGA sizing can be used to calculate the SGA_TARGET value (Recommended to use 10G AMM automatic memory mgmt)large_pool = Add additional 600kprocessess= 16

126. ASM Best PracticesDatabase-ASM Best PracticesShared_pool parameter Find out how much data will be stored in ASMFor diskgroups using external redundancy = (Every 100GB of space needs 1MB of extra shared pool) + 2MFor diskgroups using Normal redundancy = (Every 50GB of space needs 1MB of extra shared pool) + 4MFor diskgroups using High redundancy = (Every 33GB of space needs 1MB of extra shared pool) + 6MASM init.ora parameterprocesses = 25 + Add 15 per database connected to ASM

127. ASM ManagementSQLPLUSDBCA (Database Configuration Assistant)Enterprise Managerasmcmd – command line access to ASM

128. ASM ManagementSQLPLUSCreate/Drop disk groupCreate diskgroup DATA external redundancy disk ‘ORCL:*’;Alter Disk groupAlter diskgroup DATA ADD/DROP/RESIZE disk..Alter diskgroup DATA add ..rebalance power {0|11};Alter diskgroup DATA MOUNT/DISMOUNT ..Alter diskgroup DATA ADD/ALTER/DROP TEMPLATE ..Alter diskgroup DATA DROP FILE/DIRECTORY/ALIAS ..Alter diskgroup DATA check all repair; Checks inconsistency of diskgroup metadataASM diskgroup and Disk v$ASM viewsSelect all v$asm_* views

129. ASM ManagementDBCA

130. ASM ManagementEnterprise Manager

131. ASM Managementasmcmdlsct – list all the connected clients – from v$asm_clientlsdg – list the diskgroup from v$asm_diskgroupdu, ls, mkdir, pwd, rm, rmalias

132. ASM TroubleshootingASM Startup failsMake sure CSS is started and running in the correct modeCSS should be started from the ASM home in single-instance setups and from the CRS home in cluster setupMake sure enough memory is available for ASM

133. ASM TroubleshootingASM trace filesEach ASM instance has trace directoryAlert.log

134. ASM TroubleshootingASM Disk DiscoveryCan’t discover disksCheck to see if the asm_diskstring parameter matches the desired disk pathMake sure that the device is both readable and writable by ASMMake sure that the device is on an OS partition rather than on the raw disk itself; i.e., it should not include the partition that contains the VTOC.

135. ASM TroubleshootingASM Disk DiscoveryCan’t discover disksIf using ASMLIBEnsure ASMLIB listdisks lists all required disksMake sure that ASMLIB scandisk returns with <OK>Verify the correct library-specific discovery string is used; i.e. it should be “ORCL:*”ORA-15020: discovered duplicate ASM diskAsm_diskstring resolves to duplicate pathsIf using multipathing tools, specify the virtual device, or a single path

136. ASM TroubleshootingDiskgroup IssuesDisk group out of space despite added storageMake sure that all ASM devices are of similar capacity, including the ones being addedIf failgroups contain more than one device, make sure that the total capacity of each failgroup is similar across all failgroups.If rebalance hangs because there is no more space availableThen add more storage of similar sizeMake sure that the asm_power_limit parameter is not set to zero

137. ASM TroubleshootingDiskgroup IssuesUnexpected Disk group dismountWARNING: offlining mode 3 of disk 1/0x0( DATA_1_0001)Indicates that there was an I/O error to a particular diskERROR: PST-initiated MANDATORY DISMOUNT of group DATA_1Indicates that trying to take the disk offline would have caused data loss, so ASM is dismounting the disk group instead.In both cases look for disk I/O errors from OS and storage layers

138. ASM TroubleshootingRecovering from Transient disk failuresFor ASM redundancy diskgroups, there may be cases where disks temporarily lose connectivity or have transient failuresV$ASM_DISK query shows this for a disk:NAME MOUNT_STATUS STATE--------- ----------------------- --------DATA MISSING HUNGEnsure you’ve recovered from transient failure, v$asm_disk will now show a MEMBER diskAdd disks back in the diskgroup using the alter diskgroup add disk and specifying the FORCE option

139. ASM TroubleshootingDatabase ConnectionsSymptom: Database unable to connect to ASM instance.ASM instance is not running or has not mounted the diskgroupDB user is not in the primary member of CSS groupSymptom: Subsequent Database mount cannot find the controlfileCheck that ASM instance is running and has mounted the diskgroupIf OMF was used to create the controlfile then one needs to create an alias for the OMF file and update the parameter file

140. ASM TroubleshootingDatabase ConnectionsSymptom: Database does not startup due to errors in spfile stored in a diskgroupCopy the spfile out of the diskgroup to a local filesystem using create pfile from spfile=‘+dg/spfile.ora’

141. ASM TroubleshootingMemory Related Issues (Shared pool, Large Pool, Cache Size, etc)Increase respective memory size, based on the suggestions made earlierNote that the memory requirements for the database and the ASM instances are different

142. Migrating DB to ASMMigrating from non-ASM to ASM rman utilityDBMS_FILE_TRANSFER API Enterprise Manager which in turn uses RMAN

143. Orion ToolOracle Input Output NumberMeasuring I/O of the storage using ORIONNot supported by Oracle

144. Lab 4 : Migrating Database to ASMLab 5 : Orion Tool

145. ASM 11G new featuresRe-sync ASM disks after transient failuresOnly changed blocks are resync’edAlter diskgroup DATA online disk D3_0001;Alter diskgroup DATA online all;BenefitsFraction of time to re-establish redundancyEnables pro-active maintenanceFast recovery in extended clusters

146. ASM 11G new featuresPreferred Read Failure groupAllows local mirror read operations in extended clusters.Eliminates network latencies

147. ASM 11G new featuresRolling upgrade and patchingMaximizes database availability in a cluster (RAC)How does it workPlace cluster in “Rolling Migration” modeBring down ASM on a cluster nodeUpgrade or patch ASM softwareRe-start ASM (Cluster can operate in mixed ASM version mode while rolling migration mode is on)Repeat the same for all nodesStop ‘Rolling Migration’ mode

148. ASM 11G new featuresVariable ExtentsASM Extent MapCollection of data extents that defines ASM fileVariable size extentsExtent size grows automatically with file sizeBenefitsReduce memory utilization in SGAImproved file create/openIncrease maximum ASM file size100% automatic

149. ASM 11G new featuresMaximum Allocation Units and Variable extentsHigher performance for large Segment I/O (DW)Allocation Unit (AU)Select at disk group creation time and may be 1/2/4/8/16/32/64 MBVariable size ASM file extentsExtent size = AU size up to 20,000 extentsExtent size = 8*AU up to 40,000 extentsExtent size= 64*AU beyond 40,001 extentsStripingCoarse Stripe size always = one AUFine Stripe size always = 128 KB

150. ASM 11G new featuresDisk Group AttributesMaintain ASM and RDBMS compatibility based on requirementsAllow user to try new version before committing

151. ASM 11G new features(Disk group attributes)

152. Q & A

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