While many Oracle shops already enjoy the high-availability benefits of clustering, the perceived complexity of grid computing still scares some users off, a new survey has found.
A recent survey of Independent Oracle Users Group (IOUG) members reveals that adoption of Oracle Real Application Clusters (RAC) and other clustering products is now widespread, but grid computing is still a fledgling technology. The results also suggest that some Oracle users aren't quite sure of the differences between RAC and grid.
The survey pooled 220 responses from IOUG members representing a wide range of industries. Half of those surveyed were database administrators (DBAs), with other respondents including IT managers, directors, CIOs and consultants. Most organizations represented in the survey have both Oracle 9i and Oracle 10g databases in production.
More than a third of those surveyed have already implemented RAC, and an equal number (35%) have a third-party clustering product in place. In contrast, only about one in four respondents currently have Oracle Grid in production or are planning a grid implementation. Among the remaining 75% of respondents, just over half reported no plans for grid at all, with another 12% unsure about grid plans and 11% unclear on the difference between RAC and grid. The survey revealed that complexity is the main reason for resistance to grid computing.
Are fears about grid deployment founded?
Concerns about the considerable amount of time and energy it takes to implement grid computing are valid, said Ari Kaplan, president of the IOUG, but as with any new technology, organizations need to expend resources to realize a return on investment.
"There are clear business benefits [with grid] -- availability and performance -- but there are also challenges. It requires additional training and additional hardware," he said.
According to Bill Cullen, an Oracle DBA and independent consultant who specializes in high-availability technologies, grid fears are not surprising.
"Tech managers are always leery of wasting money on the five-dollar solution for the five-cent problem," Cullen said. "I'm not saying that's what grid is, but that's what decision-makers are fearful of."
Cullen said that there is currently a shortage of grid database expertise, and as a result, "managers are scared of the complexity, training costs and [the potential for] mucking up existing production applications that are working well."
Much of the concern about grid's complexity may be a holdover from earlier versions of the technology, added Kaplan.
"[Oracle] Parallel Server and early versions of grid were very complex and challenging to implement, but with 10g [Grid], Oracle has truly made leaps and bounds in ease of installation," Kaplan said. "People may have tried it and not had success and haven't taken a look at it again."
Cullen added that reluctance to deploy new technologies is simply the norm in IT.
"I remember when managers were worried about the complexity of the 7.3 database," he said. "I may not go as far as to say [that concerns about complexity are] unfounded, but it is certainly missing the forest for the trees, because the reality is that grid reduces complexity, makes larger environments more manageable and lowers costs in the long run."
According to the survey, among sites that do have grid in place, data warehousing and business intelligence are the most prevalent application areas. Almost three out of four of these sites report direct benefits from grid, with 45% citing increased availability of applications and services. Other reported benefits include enhanced failover, backup and recovery and increased scalability.
While most grid sites currently only have two to four nodes in production, almost one in four respondents said they plan to deploy 12 or more nodes within a year. This high number surprised Kaplan, but he was glad to see people taking more advantage of the potential benefits of having more nodes.
"You get the high availability with two nodes," he said, "but beyond two nodes you start to see more performance improvements."
The survey also revealed that many companies are moving from clustering to grid. Half of RAC users are already moving to grid or are planning to make the switch, citing greater flexibility as the main reason. According to Kaplan, grid is more powerful because it offers more redundancy, not just in the database but in the application servers and elsewhere.
"The more redundancy you build in, the higher the availability and the lower the risk," Kaplan said.
How is Oracle Grid different from RAC?
Oracle RAC is an instance of a single database and application running across multiple clustered processors. A group of computers in a cluster are organized to perform the same function. According to the executive summary of the IOUG survey, clusters are generally perceived as a strategy for failover -- if one of the nodes goes down, the application can keep running on another processor.
For RAC, clustered processors must be identical. Grid architecture, in contrast, does not have this requirement. A grid is a collection of resources and may consist of multiple clusters. Grid systems are mainly perceived as a strategy for workload balancing, enabling the activation of new nodes as demand for computing power increases, according to the summary report.
Some survey respondents indicated confusion about the difference between RAC and grid. "Some people use [the terms] synonymously," Kaplan said. "People are very familiar with Oracle RAC because it's been out so long -- it's an actual product. 'Grid' really refers to a larger thing. Oracle RAC is just one piece of the grid."
According to Cullen, there's conflicting information and confusion even among the pros about the potential benefits of RAC versus grid.
"I don't think even the experts agree on the differences between clustering and grid, at least as far as the benefits between the two," he said. "In essence, grid allows you to borrow, distribute and reallocate your resources to where you need it, when you need it. It eases management and lowers costs by utilizing less expensive hardware and diminishing unused or underutilized resources. Many sites miss this concept and view Grid as RAC-Plus."
Cullen also found the concept of moving from RAC to grid problematic.
"While I know of many RAC installations without [Oracle] Grid and understand you can have grid without RAC, I am not sure I get the scenarios where the business requirements would dictate abandoning RAC for a solely grid architecture," he said.
What does a typical RAC or grid implementation look like?
Both Kaplan and Cullen report that Linux is the operating system of choice for RAC and grid deployments.
"People seem to like to use Oracle's Grid Control over at least eight version 10gR2 blade nodes using ASM [Automatic Storage Management], with Linux being the preferred OS," Cullen said. "Linux is popular because it runs very nicely on smaller machines with one to four CPUs, and it is much more cost-friendly when you start scaling out multiple nodes."
"Red Hat Linux is extremely popular -- in my experience, the most popular -- followed by Solaris and HP-UX and then AIX," he said.