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Oracle Database Server 12c
Pros and Cons
Hans Forbrich
Forbrich Consulting Ltd
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Based in Alberta, Canada
Oracle DB 12c MultiTenant
Fact
Oracle DB 12c is the largest architectural
change since Oracle8i
Oracle DB 12c MultiTenant
Fact
Oracle documentation refers to the non-
Multi-Tenant architecture as
“Pre-12c”
Oracle DB 12c MultiTenant
Fact
Multi-Tenant is available in ALL Editions of
Oracle Database 12c
.
Personal
Enterprise
Standard
Oracle DB 12c MultiTenant
Fact
Multi-Tenant Option is required
ONLY WHEN MULTIPLE PLUGS ARE
USED
Oracle DB 12c MultiTenant
Fact
The changes in commands due to the new
Multi-Tenant architecture can take a long
time to become comfortable
If you have been using Oracle DB since
Oracle9i or older, PLAN on 6 months to re-
train your fingers
Oracle DB 12c MultiTenant
Fact
Multi-Tenant Architecture
Is the FUTURE
Get Used to it NOW
Oracle DB 12c MultiTenant
SO
What has changed?
And
Are there concerns and benefits?
The way we were
• Background processes for each instance
• http://docs.oracle.com/database/121/index.htm
• Reference Manual, Appendix F
• 99+ Background Processes *possible*
For Each Instance
Oracle DB 12c MultiTenant
The way we were
• DBA access to the database:
Oracle DB 12c MultiTenant
The way we were
• And verify our database information
Oracle DB 12c MultiTenant
The way we were
• And create a new user
Oracle DB 12c MultiTenant
New Architecture Exactly the same – but different
Oracle DB 12c MultiTenant
The way we need to be
• With the new architecture, access Service
Oracle DB 12c MultiTenant
Some of the Architecture
changes to think about • Single Instance or RAC Cluster
• Multiple, pluggable, databases
• One set of redo logs per instance
• One target standby
• One undo tablespace per instance
• One OR more temp tablespaces
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Services
• Not necessarily in tnsnames.ora
Oracle DB 12c MultiTenant
Services
• But each PDB has it’s own service
Oracle DB 12c MultiTenant
Reality
• We use SID everywhere
• Many of our methods/scripts will break
• Any applications need to be reviewed
• Watch for Java, JEE apps using SID
• Opportunity
• Convert to Service NOW
• Decide which to use EZ-Connect, which TNS
Oracle DB 12c MultiTenant
Admin Scripts
• Many use “/ as sysdba”
• Use SERVICE to get to correct container
• Do not use OS Authentication
• Many new roles: OSBACKUP, OSKM, OSDG
• Now need to be aware of CON_ID
• Not all actions at all levels
• Some actions restricted to ROOT
• Some actions may be performed at PDB
Oracle DB 12c MultiTenant
One SID to Bind Them
• One per host?
• SLA
• Patching
• SGA
• PGA
• Huge Pages
• Backup
• Standby
Oracle DB 12c MultiTenant
One Instance per host
• We have long wanted ONE instance per host
• Properly use available resources
• Manage memory, CPU, I/O
• But have had to oversize hosts for peak load
• And then add more instances to use free space
• Now this is ‘possible’
• But is that a good thing?
Oracle DB 12c MultiTenant
Before: Instances
• Plural !!
• Many background processes duplicated
• DBA manually balances SGA, PGA, etc
• No ‘ALTER TO MOUNT’
• Shutdown entire instance
Oracle DB 12c MultiTenant
Now: Instances
• Likely one per host!!
• Background processes not duplicated
• But may have slave processes
• Or threads
• Resource manager balances
• Individual databases
• Individually started/stopped
Oracle DB 12c MultiTenant
$ORACLE_HOME
• SLA
• One HOME = one Service Level Agreement
• Patching
• Everything in one HOME patched together
• No proper resource management
• Intra-Instance ONLY
Oracle DB 12c MultiTenant
Service Level Agreement (SLA)
• The Service Level Agreement is a formal
(documented) or informal (discussed)
agreement related to
• Uptime
• Maintenance Down time
• Unscheduled Down time response
• Patch level, patch frequency
Oracle DB 12c MultiTenant
Before: … SLA
• We basically used ORACLE_HOME to
implement one SLA
• Multiple Instances in same HOME –
• IF they can (must be) patched together
• Often one HOME = one Application
• Tricky to administer
Oracle DB 12c MultiTenant
Now: … SLA
• We basically used Instance to implement
one SLA
• Multiple Databases in same Instance - IF
they can (must be) patched together
• One Database = one Application?
• But potentially costly to
administer
Oracle DB 12c MultiTenant
Before: Patching
• Many patches required some down time
• Especially non-RAC
• Stop instance
• Apply patch
• Test patch
• Make instance available again
Oracle DB 12c MultiTenant
Now: Patching
• It may be possible to *move* the
Pluggable Database (PDB) to another
instance during the patch process, and
then restore it after patch
• Minimize down time
Oracle DB 12c MultiTenant
Shared Global Area (Memory) SGA
• Multi-tenant does not significantly save on
SGA, as compared to multiple instances
• New SGA size = Σ Individual SGA
• Need to size Memory & Semaphores
based on possible maximum utilization to
avoid restart entire instance
• May impact kernel configuration
• Interaction with Sys Admins
Oracle DB 12c MultiTenant
Process Global Area (Memory) PGA
• Theoretically fewer processes
• Same number of user processes
• Duplicate background processes eliminated
• However, these are all in ONE instance
• Need to look at PGA_AGGREGATE_TARGET
• May need to manually manage more
sessions
Oracle DB 12c MultiTenant
Huge Pages (Memory)
• The SGA is now potentially much bigger
• There is NO reason to avoid Huge Pages
Except that
Automatic Memory Management is not
compatible with Huge Pages
Oracle DB 12c MultiTenant
Impact on Tuning
• Simple Tuning involves ONE SQL
statement in isolation
• Advanced (and recommended) Tuning
involves one or more SQL concurrent
statements, and interactions
Oracle DB 12c MultiTenant
Impact on Tuning
• One huge tuning problem has been the impact of non-visible resources on instance resources
• Other instances
• Other applications
• Multi-tenant should reduce the instances and make advanced tuning potentially simpler.
Oracle DB 12c MultiTenant
Backup
• Why do we back up?
• Recovery
• Second copy
• Archive
• With pluggable databases, we may want
to re-think the purpose of backups
Oracle DB 12c MultiTenant
Backup differences
• Multi-tenant allows backup of
• Entire Container Database (CDB)
• Root only • RMAN: BACKUP DATABASE ROOT;
• One, or more, Pluggable Databases • RMAN: BACKUP PLUGGABLE DATABASE HR,…;
• Many backup strategies will need to be
rethought
Oracle DB 12c MultiTenant
Backup Differences
• The REDO Logs are common to all PDBs
• Need to think about ArchiveLog backup
when backing up individual PDBs
• Use Backup Optimization to include only
those ArchiveLogs that are needed
• Backup *all* ArchiveLogs as a completely
separate job?
• Recovery Catalog HIGHLY recommended
Oracle DB 12c MultiTenant
StandBy and High Availability
• RAC is fully compatible with Multi-tenant
• Even better, as RAC already thinks ‘services’
• Data Guard is another matter
• One standby for Container
• As of 12.1.0.2 ‘CREATE PLUGGABLE DATABASE’
includes a STANDBYS=ALL|NONE
Oracle DB 12c MultiTenant
Enterprise Manager
• EM Express
• Too light?
• Suitable for quick DBA checks
• Cloud Control 12c
• Significant time investment to get started
• But worth it!
Oracle DB 12c MultiTenant
Enterprise Manager Cloud Control
• Cloud Control 12c (12.1.0.4) is aware of
Multi-Tenant
Oracle DB 12c MultiTenant
OEM CC
• Monitor and manage Instance & Cluster
• Monitor and manage CDB$ROOT
• Monitor and manage PDBs
• Create, Move, Destroy PDBs
• Everything can be scripted
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Cloud Control
• I would not want to run a multi-tenant
environment without Oracle Enterprise
Manager 12c Cloud Control 12.1.0.4
• Core is included with DB license
• Good graphical overview
• EM CLI will become very important
Oracle DB 12c MultiTenant
Conclusion
• Multi-tenant is a significant architectural change
• It IS the future and NOW is the time to get started
• There are lots of things to look at, think about and worry about
• Reference the Concepts Manual, Chapters 17,18 and Administrator’s Guide, Chapters 36-46 • http://docs.oracle.com
Oracle DB 12c MultiTenant
Oracle DB 12c MultiTenant
Questions?
Oracle DB 12c MultiTenant
Thank You
Hans Forbrich
mailto:hans@forbrichcomputing.ca
http://www.forbrichcomputing.com
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