I recently heard an Oracle Executive Vice President in Server Technologies development at Oracle cite RAC adoption at somewhere along the lines of 10,000 RAC deployments. He then balanced that number by stating there are on the order of 200,000 to 250,000 Oracle sites. Real Application Clusters has been shipping for just under 6 years now.
Real Application Clusters Adoption
There have been a lot of things standing in the way of RAC adoption. First, applications need to be tested to work with RAC. It took ages, for instance, to have even Oracle E-Biz suite and SAP certified on RAC. Second, if RAC doesn’t solve a problem for you, the odds are small you’ll deploy it. Third, RAC was introduced just prior to the major global IT spending downturn post-9/11, and RAC is not inexpensive. I’m sure there are third, fourth and many more reasons, some of which are centered more along techno-religious lines than purely technical.
I’ve been very involved with RAC since its initial release because my former company, PolyServe, helped some very large customers adopt the technology. All along I’ve been interested about any factors that hold back RAC adoption. In my personal experience, one significant factor is not really even a RAC issue. Instead, the difficulties in dealing with shared storage has historically put a bad taste in people’s collective mouths and technology like ASM only addresses part of the problem by handling the database—but none of the unstructured data necessary for a successful RAC deployment. That’s why I like NFS–but I digress.
A Poll
In this post on the oracle-l email list, a fellow OakTable Network member posted an invite to participate in a poll regarding Real Application Clusters. It only has a few questions in order to garner as much participation as possible. I do wish, however, it would ask one very important question:
Why aren’t you using RAC.
I encourage all of you RAC folks to participate in the poll here: A Poll About RAC. Let’s get as much valuable information out of this as possible. If you have a minute, maybe you non-RAC folks can submit a comment about why you don’t use RAC.
At the top of the Poll webpage you can click to get the current results.
Kevin Closson's Blog: Platforms, Databases and Storage 
Our reason for not using RAC falls in to the “it does not solve a problem for us” category.
Our biggest servers are 4 way x86 boxes, and they have more than enough horspower for our needs.
Our busiest server is actually a 2 way Xeon running linux.
It has 7 databases on it. The backend is a EMC CX700, and
IO has not been a problem.
If I need to scale up this box, it really just needs more RAM.
That does not stop the Oracle sales folk from bringing up RAC as a HA option. My reply is that I don’t need the extra complexity, and that RAC is not by itself an HA solution.
That doesn’t mean there are no good reasons for using RAC. Another OakTable member was recently overheard to say that one of his customers had maxed out the biggest box available from their vendor.
That sounds like a good reason to use RAC.
I’m with Jared on this one currently…the DW I’m working on is not on the biggest box available from the vendor although is coming to a max out position this year. We don’t “need” RAC currently.
We have the option of using RAC to scale it in future and our app (DW) would be amenable to it I think, or we could just buy the bigger box from the current vendor, but for me it seems that we struggle on IO more than we do CPU/Memory so personally I’d be spending more money on the storage and tuning what application code we’ve got in the current environment. HA factors will also come into play during the next decision rounds as well so maybe that is a factor in favour of going down the RAC route although RAC itself is not a panacea for HA.
Time will tell as I don’t make the $$$ decisions.
Keep churning out the stuff Kevin…I’m a regular reader and it’s all very interesting – if a little over my head at times!
Kevin,
Some web browsers seem not to like your page
https://kevinclosson.wordpress.com/2007/04/12/rac-adoption-rac-justification-a-poll/
I can get other pages of yours but my IE7 refuses to display that one. It looks like it’s loading and then almost immediately redirecting somewhere else.
FYI.
Cheers,
Dominic
Seems better now though. Odd.
Did you see Mogens’ recent post about availability?
http://wedonotuse.blogspot.com/2007/04/so-few-really-need-uptime.html
I think that he articulates my thoughts about this perfectly. My experiences before and after I ventured into the strange world of consulting with companies who bought RAC corroborate this opinion. So few really need uptime.
seems that the previous comment is awaiting moderation. maybe kevin will fix it but at the moment the link is missing the last character so you get an error if you click it… here’s what it should be:
http://wedonotuse.blogspot.com/2007/04/so-few-really-need-uptime.html
In my experience I had more downtime with RAC than without.
Too many unexpected (and unexplainable) node evictions.
Single instance DB and active-passive clusters are (in my experience) more stable.
Good Work Kevin. Keep us educating and entertaining.
I have been using RAC for the last 6+ months. And in my experience i have seen more database crashes and issues than with the single instance databases. I agree with Fabrizio as RAC being more unstable than single-instance Oracle database.