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Database Upgrade/Migration Options & Tips
Sreekanth ChintalaDatabase Technology Strategist
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Agenda
• Very high level overview of Migration/Upgrade options• No technical details
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About the Speaker
• West Virginia University (M.S)
• Supporter of UT Longhorns
• 11+ Yrs of Oracle, 17+ years in IT
• RACSIG Web chair (2008-2010)
• Presenter at OIUG, OOW, Local user groups• Technical Editor• [email protected]• [email protected]
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Database Upgrade
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Database Upgrade
10gR1 11gR2
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Database Migrations
• Migrations are typically done as part of End-of-Life refresh, usually followed by Database Upgrade
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Database Upgrade Methods
• Database Upgrade Assistant GUI• Uses GUI to upgrade• The DBUA performs pre-upgrade checks
• Manual Upgrade• Performed via SQL-Plus Commands• Use pre-upgrade script to validate• Modify Cluster Registry entries for RAC Databases• .profile changes, environment variables
• Tips• Use GUI method, especially for RAC Databases• Take a backup before the upgrade• Check news groups to be aware of any known issues
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Factors
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Concerns
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Database Migration Options
Complete Downtime• Export and Import using Data Pump (or exp/imp)• CTAS• Backup & Restore• Transportable Tablespaces
Minimal Downtime• Logical/Physical Standby• EMC SRDF Copy• ASM Rebalance
• Near Zero Downtime • Oracle Streams• Golden Gate
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Export / Import
• Database needs to be down or open read only • Take an export on the source system• Copy the export dump to destination system• Import into the database
Advantages• Simple to use, proven track record• Works well for smaller DB sizes (say < 50GB)
Gotcha’s• Size of the database dictates the amount of downtime needed• Import time is 3-4 times longer than export time• Older Unix system may have 2G file size limitations.
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Export / Import
10gR111gR2Expor
t Copy
Export
Copy
Tips• Use NFS mount that can be accessed from both source and destination• Data Pump provides many features• Review the nature of data. Bring over the static tables, partitions
ahead of time, reduce the total downtime• In case of RAC instances, leverage all instances to import different
tables• Indexes can be re-built on the destination. No need to import them• Collect stats after the import• Beware of security and password changes
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SQL Plus-CTAS
• Database needs to be down or open read only • Copy the Tables via DB Link
Gotchas• Size of the database and the network throughput dictates the amount of downtime needed• Don’t use it on Live tables
Advantages• No intermediate storage needed• Operations can be performed in parallel for non-related tables
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CTAS
10gR1 11gR2
Tips• Review the nature of data. Bring over the static tables, partitions
ahead of time, reduce the total downtime• In case of RAC instances, leverage all instances to import different
tables• Indexes can be re-built on the destination. No need to import
them• Collect stats after the import
• DB Link
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Backup / Restore
• RMAN incremental backups can reduce the downtime• Copy the backups to destination system• Restore into the databaseGotchas
• Heavy DML operations may prolong the “Restore-Sync” time• Going through “Tape” can significantly add time to backup and
restore• Typically few restore (tape) resources are allocated
Advantages• Primary Database is up and running • Can use RMAN compression, parallel operations• RMAN only backups the changes and restores the needed files
Tips• Use a shared disk (NFS) between the target server• If you have to go to tape, request dedicated backup channels until
the restore is complete
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Transportable Tablespaces
• Create the empty database • Create the Metadata of the source database in the new database• Database files are moved from existing database to the other system
Gotchas• Source and target systems should have the same character set and national character set• Limitations on indexes ( Function based/domain )• Limitations on snapshot/replication• Tables and indexes to be part of the self contained set• All the partitions of a partitioned table needs to be moved as a set
Advantages• Use this option to move the databases across different platforms• Faster because it bypasses usual data extract and load processes• Efficient than export/import
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Logical/Physical Standby Option
• Available for 10.1.0.3 and above • Very minimal downtime( time to switchover )• Must setup a Data Guard environment
Gotchas• Need to modify Primary to setup Logical/Physical Standby• OS must be the same ( family) between primary and standby• Primary needs to be shut down for DB Upgrade on the target• SQL Apply reapplies the transactions. Heavy OLTP systems are
not a good candidate for Logical Standby• Doesn’t work for cross platform
Advantages• Proven technology• Changes to the production are copied over to the standby• Newer versions, you can use it to test the performance using
snapshot standby• Protection from Physical Corruption
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• Only available for EMC Storage - Symmetrix Remote Data Facility• Manages real time copies of data volumes ( at the storage level)
Gotchas• EMC solution for Symmetrix storage • Physical corruption will get carried over to the other side• The target (individual) Lun size should be equal to or larger than
source Lun
Advantages• Most simple solution to copy multi-terra byte DBs• Most of the work is on the storage team to setup SRDF• SRDF can copy the incremental block changes after initial setup
SRDF Copy Option
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ASM Rebalance Option
• Leverage ASM rebalance feature to off-load data from one storage array to another
Gotchas• Will require downtime to bring up the new system• Will require downtime to perform DB upgrades
Advantages• No disruption to primary database during rebalance• No monitoring or governance during the operation
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ASM Rebalance Option
Storage ArraysStorage Arrays
1. Add the New LUNs on the OLD system (OS)
2. Add the LUNs to the Disk Group3. Perform Rebalance4. Shutdown Old System
1. Create CRS,DB,ASM on new system2. Copy SPFILEs (DB,ASM)3. Add the New LUNs on the New
system (OS)4. Bring up the database
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Oracle Streams
• Little or no downtime• Source and Targets can be any version to any platform
Gotchas• Limitations on some data types ( CLOB/BLOB)• Extremely complex to implement & maintain• Longer development cycles• Need highly skilled DBAs
Advantages• Can be used to migrate between different platforms and versions
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Golden Gate Option
• Little or no downtime• Source and Targets can be any version to any platform
Gotchas• Requires Golden Gate License• investment of intermediate platform when moving from one OS
Family to another
Advantages• Moderately complex to implement• Provides Fall back options• You can leverage the infrastructure many times• Best near Zero Downtime Option
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8i & 9i 10g/11g Migration Overview
Goldengate Capture to Trails
Create Clone DB via RMAN
8i/9i
ASM Storage
XTTS – Transport Tablespace
Goldengate Apply from Trails
Real-Time ReplicationFail back!Reverse ReplicationServer & StorageProvisioning
DBA BeginsMigration
Production
App Testing
Switchover to RAC Database
Fail back Strategy Post-Migration
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In place Migrations of OS
Complete Downtime to the server being upgraded• Data Guard can be up and running while the migration is taking
place• Operating System Upgraded wipes out internal drives • Newer Cluster Version wipes out the Clusterware drives• Data Luns inside ASM are intact.
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In place Migration Steps
DBA1. Create and save (elsewhere) pfile from the spfile
Linux Engineer1. Re-image all cluster nodes to new OS2. Post-build steps an 11g RAC cluster. 3. Check and validate if the cluster is healthy and operational
DBA1. Restore the saved pfile configuration files and start ASM.2. Mount the expected ASM disk groups and start the DB.3. By starting the DB under the 11g binaries, this converted
the 10gR2/64 DB to 11g. Run DB Upgrade script