Introduction

Let’s have a look at how to make Oracle database as simple as it was before.

Oracle database is a great piece of software, yes it’s quite expensive, but it’s still the reference and most of the companies can find a configuration that fits their needs according to a budget. Another complain about Oracle is the complexity: nothing is really simple, and you’ll need skillful DBA(s) to deploy, manage, upgrade, troubleshoot your databases. But complexity is sometimes caused by wrong decisions you make without having the knowledge, mainly because some choices add significant complexity compared to others.

The goal

Why the things need to be simple?

Obviously, simplification is:

  • easier troubleshooting
  • more “understandable by the others”
  • reinstallation made possible in case of big troubles
  • avoiding bugs related to the mix of multiple components
  • less work, because you probably have enough work with migration, patching, performance, …
  • more reliability because less components is less problems

On the hardware side

Rules for simplifying on the hardware side are:

  • Choose the same hardware for all your environments (DEV/TEST/QUAL/PROD/…): same server models, same CPU family, same revision. Make only slight variations on memory amount, number of disks and processor cores configuration if needed. Order all the servers at the same time. If a problem is related to hardware, you will be able to test the fix on a less important environment before going on production
  • Don’t use SAN: SAN is very nice, but SAN is not the performance guarantee you expect. Adopt local SSD disks: NVMe type SSDs have amazing speed, they are a true game changer in today’s database performance. Getting rid of the SAN is also getting rid of multipathing, resource sharing, complex troubleshooting, external dependencies and so on
  • Provision very large volumes for data: dealing with space pressure is not the most interesting part of your job. And it’s time consuming. You need 4TB of disks? Order 12TB and you’ll be ready for each situation even those not planned. For sure it’s more expensive, but adding disks afterall is not always that simple. It makes me think about a customer case where trying to add a single disk led to a nightmare (production down for several days)
  • Consider ODA appliances (Small or Medium): even if it’s not simplifying everything, at least hardware is all that you need and is dedicated to Oracle database software
  • Think consolidation: Oracle database has a strong database isolation thus leading to easy consolidation. Consolidate to limit the number of servers you need to manage is also simplifying your environment
  • Avoid virtualization: without talking about the license, virtualization is for sure underlying complexity

On the system side

Some rules are also good to know regarding the system:

  • Go for Redhat or Oracle Linux: mainly because it’s the most common OS for Oracle databases. Releases and patches are always available for Linux first. UNIX and Windows are decreasing in popularity for Oracle Databases these past 10 years
  • Same OS: please keep your operating systems strictly identical from development to production. If you decide to upgrade the OS, do that first on TEST/DEV and finish with production servers without waiting months. And never update through internet as packages can be different each time you update a system
  • Limit the filesystems number for your databases: 1 big oradata and 1 big FRA is enough on SSD, you don’t need to slice everything as we did before, and slicing is always wasting space

On the software side

A lot of things should be done, or not done regarding software:

  • Install the same Oracle version (release + patch) and use the same tree everywhere. Use OFA (/u01/…) or not but be consistent
  • Limit the Oracle versions in use: inform your software vendors that your platform cannot support too old versions, especially non-terminal releases like 11.2.0.3. 19c, 12.1.0.2 and eventually 11.2.0.4 are the only recommended version to deploy
  • Don’t use ASM: because ext4 is fine and SSDs now bring you maximum performance even on a classic filesystem. ASM will always be linked to Grid Infrastructure making dependencies between the DB Homes and that Grid stack, making patching much more complex
  • Don’t use RAC: because most of your applications cannot correctly manage high availability. RAC is much more complex compared to single instance databases. Not choosing RAC is getting rid of interconnect, cluster repository, fusion cache for SGA sharing, SAN or NAS technologies, split brains, scan listeners and complex troubleshooting. Replacing RAC with Data Guard or Dbvisit standby is the new way of doing sort of high availability without high complexity

Simplify backup configuration

For sure you will use RMAN, but how to simplify backups with RMAN?

  • Use the same backup script for all the databases
  • Use the same backup frequency for each database because when you need to restore, you’d better have a fresh backup
  • Configure only different retention on each database
  • Backup to disk (the most convenient being on a big nfs share) and without any specific library (backup your /backup filesystem later with your enterprise backup tool if needed)
  • provision large enough filesystem to never need to delete backups still in the retention period

Using the same backup strategy means being able to use the same restore procedure on all databases because you always need a quick restore of a broken database.

Always backup controlfile and spfile on the standby databases, the resulting backupset has a very small footprint and makes easier restore of the standby using database backupsets from the primary without the need for duplication.

Consider RMAN catalog only if you have enough databases to manage.

Simplify database management and configuration

  • Create scripts for database configuration and tablespace creation (for example: configure_SID.sql and tablespaces_SID.sql) to be able to reconfigure the same database elsewhere
  • don’t create grid and oracle users if you plan to use Grid Infrastructure/ASM: as a DBA you probably manage both ASM and database instances. Instead of loosing time switching between these 2 users, configure only one oracle user for both
  • never use graphical tools to create a database, deploy an appliance, configure something: because screenshots are far less convenient than pure text commands easily repeatable and scriptable
  • Use OMF: configure only db_create_file_dest and db_recovery_file_dest and Oracle will multiplex the controlfile and the redologs in these areas. OMF is also naming datafiles for you: there is no need for manual naming, who really cares about the name of the datafiles?
  • Don’t use multitenant: multitenant is fine but it’s been years we’re living with non-CDB databases and it works like a charm. You can still use non-CDB architecture in 19c, so multitenant is not mandatory even on this latest version. Later migration from non-CDB to pluggable database is quite easy, you will be able to use multitenant later
  • Keep your spfile clean: don’t specify unused parameters or parameters that already have the given value as a standard. Remove from the spfile these parameters using ALTER SYSTEM RESET parameter SCOPE=spfile SID='*';

Simplify patching

Patching can also be simplified:

  • Patch once a year, because you need to patch, but you don’t need to spend all your time applying each PSU every 3 months
  • Start with test/dev databases and take the time to test from the application
  • Don’t wait too much to patch the other environments: production should be patched few weeks after the first patched environment

Simplify Oracle*Net configuration

Simplifying also concerns Oracle*Net configuration:

  • Avoid configuring multiple listeners on a system because one is enough for all your databases
  • put your Oracle*Net configuration files in /etc because you don’t want multiple files in multiple homes
  • Keep your Oracle*Net configuration files clean and organized for increased readability

Make your database movable

Last but not least, one of the biggest mistake is to create a strong dependency between a database and a system. How to make your database easily movable? By configuring a standby database and using Data Guard or Dbvisit standby. Moving your database to another server is done within a few minutes with a single SWITCHOVER operation.

Using standby databases make your life easier for all of these purposes:

  • you need to move your server to another datacenter
  • a power outage happened on one site
  • you need to update hardware or software
  • you suspect a hardware problem impacting the database

Don’t only create standbys for production databases: even development databases are some kind of production for developers. If a database cannot be down for 1 day, you need a standby database.

Finest configuration is not dedicating a server for the primaries and a server for the standbys but dispatching the primaries between 2 identical servers on 2 sites. Each database having a preference server for its primary, the standby being on the opposite server.

Conclusion

It’s so easy to increase complexity without any good reason. Simplifying is the power of saying NO. No to interesting features and configurations that are not absolutely necessary. All you need for your databases is reliability, safety, availability, performance. Simplicity helps you in that way.


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by
Jérôme Dubar