You most probably don't need an RMAN catalog database

Introduction to the whitepaper

Yury Velikanov & Community

Sunday, Sep 22, 2:15 PM - 3:15 PM Moscone West - 3014

Session ID# UGF9741#OOW13 @yvelik

About Yury

Google: Yury Oracle[phone|email]

Twitter, LinkedIn, Blog, Slideshare, YouTube

Oracle ACE DirectorOracle Certified Master (9i/10g/11g + 15 OCP certificates)

Oracle DBA 15+ years (42+ months working for Pythian)

10 Problems with your RMAN backup script (author)12 000+ views on SlideShare.net

About Yury

Google: Yury Oracle

10 Problems with your RMAN backup script (author)12 000+ views on SlideShare.net

About Pythian• Recognized Leader:

– Global industry-leader in remote database administration services and consulting for Oracle, Oracle Applications, MySQL and Microsoft SQL Server

– Work with over 250 multinational companies such as Forbes.com, Fox Sports, Nordion and Western Union to help manage their complex IT deployments

• Expertise:– Pythian’s data experts are the elite in their field. We have the highest concentration of Oracle ACEs on

staff – 10 including 3 ACE Directors – and 2 Microsoft MVPs. – Pythian holds 7 Specializations under Oracle Platinum Partner program, including Oracle Exadata,

Oracle GoldenGate & Oracle RAC

• Global Reach & Scalability:– Around the clock global remote support for DBA and consulting, systems administration, special

projects or emergency response

Community involvement

Agenda• Introduction• Why RMAN catalog is an overhead? / COST• Cases when catalog database is a MUST• Benefits of using RMAN catalog / VALUE

• Catalog use-cases– Catalog & MML integration– Catalog & DR– Catalog & FS

• Practical hints for catalog usage

CTL vs DB

DB Catalogdoesn’t provide more

HISTORY!

Introduction – Why?• Many DBAs use RMAN catalog because

– It was a default option in 8.0– It is recommended by Oracle– It was created before them

• Many DBAs don’t– Use most of the catalog benefits– know how to assess cost involved– know how to justify catalog existence

@dbareactions

COST

Complexity

RMAN catalog is an overhead COST• IMPLEMENTATION COST• MAITENANCE & RUNNING COSTS

• DEPENDENCIES• DOWNTIME• AVAILABILITY• TUNING• BACKUP

•COST per database

- More databases - less cost- Cost vs Risk

A MUST

RMAN catalog database is a MUST• Disaster Recovery

– Data Guard (standby database)– Backups from both DR sides– Shared backups media

RMAN catalog database is a MUST• Control File size is way to big

– control_file_record_keep_time– Manage retention (if applicable)– Restore alternative MML handle

RMAN catalog database is a MUST• KEEP

– Keep a backup for longer than current retention policy allows– Long term backups need a special care and should be treated

as archiving• MML retention should be adjusted as necessary• Other tape pool / file system than regular backups• oracle database software & operational system

– There are alternative ways (file system)

• RESTORE PREVIEW + OS copy• BACKUP + UNCATALOG

VALUE

RMAN catalog Benefits / VALUE

• Additional bird level view - control level– Many databases– Small DBA team– Scheduling issues– Manager’s view

RMAN catalog Benefits / VALUE

• Volumes & Throughput monitoring– Day to day monitoring – Report deviations (archived logs)

– Troubleshooting data– Tuning (compression, IO vs CPU vs TIME)

– Chargeback

Capacity planning / VALUE• Challenge (centralized NFS)

– Used for many databases backups– Retention policy varies– Incremental backups + Weekly cycles– RAC multiple backups from different nodes

• Solution – Catalog DB– Centralized data for all databases– Regular data snaps– Custom data analysis tables

RMAN catalog Benefits / VALUE• MML & Catalog DB

– Tends to have longer retention policy• Often retention policy isn’t managed by RMAN

– Simplifies and unifies controlfile recovery• There are alternatives, e.g. MML handle from log files

RMAN catalog Benefits / VALUE• RMAN scripts

Pros– Standard way to backup– Centralized control / easer change

Cons– Dependency from RMAN catalog– Limited syntax

• About Stored Scripts: Any command that is legal within a RUN command is permitted in the stored script.

!shell rules!

VALUE• Additional high-level view of backups• Volumes & Throughput monitoring• Information for Capacity planning• Simplifies controlfile recovery (MML)

• Repository for generic RMAN scripts

Catalog Doesn’t• Keep longer history• Replace control file backups

CATALOG USE-CASES

MML, DR, FS

Catalog & MML integration• Control File Auto recovery (challenge)

– How it works• CONFIGURE CONTROLFILE AUTOBACKUP ON• standard handle name (%F format)c + {database ID} + {date} + {XX}

• XX - hexadecimal incremental from 00 to FF– Restore

• Restore freshest controlfile• RMAN Tries FF, FE, ….. 01, 00

– MML 1 round trip 2-5 minutes• 240 roundtrips = 8-20 hours

maxseq and maxdays

Catalog & MML integration• Alternative control file restore options

– MML REPOSITORY– RMAN LOG– HANDLE name

• RMAN: “ENV=” or “format”

• Catalog addresses– Difficulties in MML & DBA communications– Absence of MML access– Standard way to restore (easier)

Catalog, MML & RETENTIONRMAN rarely used for retention management

– Typically there are many MML clients• File systems• MS Exchange / Lotus Domino• Other databases

– There are pools to send backups to• Weekly• Monthly• Custom

There is a synchronization challenge

Catalog & Disaster Recovery• Disk based backups are local

– Accessible from one site only

• Tape based backups are global– Accessible from both sites

• Review the SITE_KEY column in RMAN catalog views• KEY: CATALOG disk based backups on other site

“Backup and Recovery Reference 11g R2”– “RMAN Backups in a Data Guard Environment”

Catalog & File System => MML• Simple unless ….

• Relies on file system to tape backups– Strong recommendation to use MML integration

• Missing backups• Too many copies for SOME backup sets

– If you use • Don’t use DELETE OBSOLETE• RESTORE … PREVIEW• Manual synchronization

PRACTICAL HINTS THE CATALOG USAGE

Practical hints for catalog usage

• DBID must be different for all databases• Do not separate Development & Production• To use or not to use RMAN catalog stored scripts?

• Use resync catalog• RMAN setup for catalog DB failures• Introduce two catalog DBs to ensure HA

CONCLUSIONS

Whitepaper!

Catalog makes it simple

• RMAN Catalog is an overhead• You may manage without it• However an RMAN Catalog

– simplifies backup management– adds additional benefits– reduces risks– there are other special cases

• Cost is opposite proportion to DB count• Consider leveraging other catalog DB benefits

If you don’t use catalog DB

• Make sure that– control_file_record_keep_time is greater than

maximum retention period you may use– You have an easy access to archive of RMAN LOG

files– You have knowledge & access to MML server

• at least you have a best friend in tapes management team

• Assess catalog DB benefits on regular basis

CTL vs DB

Google: Oracle YuryBlog, Twitter, Linkedin, ACE … email, phone number

Whitepaper!

Session ID# UGF9741#OOW13 @yvelik

THANK YOU

Google: Oracle Yury

Whitepaper!