Oracle real applicatiOn clusters (rac)cheat sheet

elevator Pitch

Oracle Real Application Clusters (RAC) enables 24 x 7 availability of database applications and horizontal scalability on low-cost servers without changing a line of code. Well over 10,000 Oracle customers of all sizes, in all industries, running all types of applications are already benefiting from reduced cost of downtime and lower hardware costs using RAC. Oracle further reduces the cost of computing by including free clusterware and automatic storage management as part of Oracle Database 11g RAC. With RAC you don’t sacrifice performance and reliability for cost.

Oracle RAC is the most popular database option and major amounts of development continue to focus on improving this option with each new database release.

high yield questions

senior it Manager (wants to improve quality of service; wants to reduce costs):

What happens when you experience –downtime and users are unable to access their database applications? – How are your database applications performing in terms of meeting users’ availability expectations? – How do you scale your existing systems (and what is the incremental cost involved) to meet growing demand?

dBa/administrator (wants to reduce complex-ity of managing databases; wants to reduce number of databases managed):

– Are you familiar with the new features of Oracle Database 11g and Oracle Real Application Clusters? – Did you know that integrated cluster services are part of Oracle Database 11g? – Did you know that Automatic Storage Management is part of Oracle Database 11g?

Mid-market prospect: – Did you know that RAC is part of Oracle Database 11g Standard Edition?

oBjection handling

i’ve read that rac can’t scale beyond 4 processors—What proof points do you have for your claims on rac’s scalability, per-formance and reliability?Certified benchmarks have proven that Real Application Clusters scales above 80% for SAP. A great example is a couple of indus-try standard TPC-C benchmarks recently run by HP. The first was running Oracle on a very big HP SuperDome SMP computer with 64 Intel Itanium2® CPUs. The second was on a 16 node cluster where each server was a much smaller and much less expensive 4 CPU SMP box. The result in this case was more than 18% higher than on the SuperDome, but what is

really interesting is that the cluster servers were using the exact same Intel Itanium2® CPUs as the SuperDome and the same total number of CPUs—64. So with the same amount of processing power Oracle RAC achieved better scalability.

Now, when you look at the cost data more closely you really see how RAC gives you more and costs you less. The big HP SuperDome costs just under $8 million while the cluster computers cost less than $3 million. The cluster was 1/3 the cost. That’s $5 million less.

Why do you say oracle real application clusters 11g is better than the competition?The basic difference with Oracle Real Application Clusters 11g is that all servers in a cluster see all of the data in the database (the competition just don’t have anything equiv alent on open systems). Because of this, you can simply add more servers to ‘scale out’ on demand, without having to redistribute data across the new set of serv-ers. Real Application Clusters acts like a single system, however failure of any single server in a cluster does not prevent access to the data from other nodes. So adding more servers to a cluster actually increases the reliability of the overall system. Another key benefit of hav-ing all nodes act as a single database is that users, applications and DBAs use the cluster as if it were one machine, in other words one database to manage, backup, etc.

Microsoft sql server and iBM dB2 have active-active failover, and it’s cheaper. Why should i use oracle real application clusters 11g instead?Competing databases do not really support active-active clustering, where two nodes in a cluster support the same application. Instead, they support dual active-passive configura-tions. In other words, Node A runs Applica-tion A, while Node B runs Application B. Each node acts as a failover machine for the other. But the same application does not run on two different nodes. With Oracle Real Application Clusters 11g, the same application runs on 2 or more nodes, with each node acting as a failover machine for all other nodes. If a single node fails, the overall processing power of the Real Application Clusters database is reduced incrementally.

My distributed applications are running fine, why should i consolidate my database applications?If your database applications are running on Oracle, they are undoubtedly supporting the need of your business. But the advantage of clustering your applications means you have fewer databases to manage. That means fewer backups, upgrades, etc. and of course less costly resources to manage your database(s).

Oracle real applicatiOn clusters (rac)cheat sheet

And by consolidating onto Oracle Real Applica-tion Clusters 11g you can expect to increase uptime (therefore reducing the cost of down-time) to 99.99% and above.

We have clustered hardware in place and can failover applications easily enough. Why do i need oracle real application clusters 11g?When running applications in a clustered architecture without Oracle Real Applica-tion Clusters 11g, you are effectively running your applications in single instance mode. Your server may be part of a cluster, but to all intents and purposes it’s running as though it were on a standalone server. In clustered architectures such as HP ServiceGuard, Sun Microsystems’ Sun Cluster and Microsoft Clus-ter Services, yes you can restart your Oracle server on any node in your cluster (since your disks are shared). This is what we mean when we talk about ‘cold failover’. Note that ‘Cold’ failover is dependent on the speed at which the hardware resources (disk volumes) can failover to their alternative server and the hardware failover could take anywhere from 5 to more than 25 minutes to recover. When using Oracle Real Application Clusters 11g, in the event of a server failure, the surviving servers auto-matically and quickly recover the failed server instance. Oracle Real Application Clusters 11g provides the fastest recovery from system fail-ures in the industry. Recovery from system fail-ures typically occurs within 60 seconds. That is a minimum of five times faster recovery than the fastest of ‘cold’ failover solutions.

We’re using data guard for failover; why do i need oracle real application clusters 11g?You’re doing the right thing by protecting your data with Data Guard. However, Data Guard and RAC solve two different problems. RAC provides you unlimited scalability and protec-tion from individual node failures, whereas Data Guard protects your data from all other failures including site disasters, data corrup-tions and human errors. RAC and Data Guard are 100% complementary technologies that have been designed to work together seam-lessly to provide maximum availability for your database applications, and they form the building blocks of Oracle Maximum Availability Architecture (http://www.oracle.com/technol-ogy/deploy/availability/htdocs/maa.htm).

Why linux? Why oracle real application clusters 11g on linux?It’s a well-known fact that you can run your business on the Intel/Linux platform for a lot less than you can on other platforms. But the reason you run your business on SMP UNIX servers is that they provided the scalability and reliability your business required in the past. In today’s cost-aware economy, busi-nesses are looking to increase availability of

their systems, and provide a better quality of service, but at a lower cost. By migrating your applications to Oracle Real Application Clusters 11g on Linux, you can provide greater levels of availability than you can with an SMP server, you can incrementally scale those systems and more importantly you can lower the cost of your entire operation. Clustering a number of small Intel servers is a LOT less expensive than a large SMP box and with a cluster you have unlimited scalability, whereas with an SMP box at some stage you’ll be faced with a migration exercise to a larger box.

oracle real application clusters is just the next generation of oracle Parallel server, right?Real Application Clusters is a completely re-written product from Oracle Parallel Server and is now in its third major release (11g). Several new patents have been granted for RAC and most of these focus on creating a clustering environment in which any application can run unchanged and achieve excellent perfor-mance, scalability and availability. Also, a huge amount of work went into making RAC easier to deal with. The beauty of the RAC architecture is that all of the work that is needed to provide good scalability is hidden from application developers and users.

What do you see as a typical hardware configuration for a rac solution?This is a good question. Note that RAC is the same product on all supported Oracle platforms: Windows, Linux, Solaris, HP-UX, etc. So, pretty much whichever system vendor you are dealing with, RAC will perform and scale well. So, in terms of system size, it really depends on your specific requirements. We see both Windows and Linux as great environ-ments to run RAC on commodity Intel-based servers, which means greater reliability, perfor-mance and scalability at lower cost. But RAC will scale at any price point. You can just as easily configure a cluster of HP SuperDomes, Sun boxes, or Linux/Windows Intel servers.

additional inforMation

RAC reference – s on Oracle.comLearn more about Oracle Real Application –Clusters on Oracle.com