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