A Short Way to Reliable Oracle RAC in Skytap
Ivaylo Nikolov
in AIX, Azure, High Availability, Migration, Power, Skytap, Skytap on Azure
Introduction
Most of our projects within Skytap on Azure have been related to AIX and Oracle workloads. In a lot of these scenarios complex clustered environments have been part of the project with clients looking to see how we will migrate, implement and support such clustering within Skytap. There have been some misunderstandings and myths generated regarding Oracle and Oracle RAC implementations in Skytap so we are sharing our experience.
Skytap MAS (Multi Attach Storage)
Skytap works with storage a bit differently from other public cloud providers. In Skytap, you have so called local disks, which are basically not local, but on an external storage and generally cannot be attached to more than one server.
In order to attach disks to more than one server in Skytap, you need to use multi-attached storage or MAS. When considering multi-attached storage, which you will obviously need for Oracle RAC implementation, you need to seriously consider the skiing of the disks. It is a good idea to balance them in size depending on the size you need. Make sure you design them well before implementation as MAS storage volumes cannot be extended afterwards. So, leave yourself a little buffer for the future as well.
Oracle RAC
Oracle RAC can be a challenge due to the uninitiated for multiple reasons. You need to be careful about networking, disks, ASM file systems and different specifics like scan address requirements and VIP addresses.
One significant advantage that you will see when implementing clustered-type environments in Skytap is how it routes shared (or cluster service) IP addresses. In contrast to Azure Native, where you need to have load balancers with floating IP in front, in Skytap you just use and failover IP addresses and they are naturally routed. In that regard, your scan IP addresses will not be a problem and you can always configure them as secondary addresses to one of the LPARs. This will reserve them within the range in order to avoid them being reused in the same subnet.
Multi-attached storage obviously will be the cornerstone of your implementation. Be sure to optimize disk parameters on the AIX so you do not hit issues with disk timeouts when configuring the RAC and spend needless time troubleshooting. There are a number of recommendations coming from Skytap and Oracle on how to optimize your AIX network and disk parameters. Be sure to take these into accounts and you should have no issues.
On the ASM level, there is nothing really specific to Skytap you should think about. Disks are presented to AIX as raw devices, which is pretty much a standard and of course afterwards they are configured as needed.
Other than that, if you get your DNS landscape right and plan and design your environments well in Skytap, you will have a really stable Oracle RAC solution.
Oracle RAC on Skytap
Having said all of the above, there are some things that you need to consider when running Oracle RAC in Skytap and any other Oracle on AIX system as well.
Make sure you always plan for monitoring as Skytap does not provide native monitoring tools. You can obviously transfer the monitoring implementation you had on-site or go for a bit more specific solutions that will help you integrate your AIX and Oracle workloads into Azure Monitor – like L3C Monitor.
From a Disaster Recovery perspective obviously, go for a different region in Skytap, but make sure to use Skytap’s native site-to-site VPNs for connectivity between the regions. They are not the fastest in the business, but have a great advantage in being free. And since DataGuard will allow you to compress logs when sending them, you should not be too stressed about bandwidth.
Skytap will offer you a very convenient way to do a quick recovery locally on systems, which use MAS drives in enabling you to template them. Skytap’s template is basically a snapshot of either the entire server or of the multi-attached storage in the environment. Whatever you choose, if you need a quick recovery, this is a really convenient way to recover the whole environment even if needed. If you need more advanced scheduling, statistics and power-off scheduling of Skytap environments – take a look at our L3C Automate tool as well.
Finally
Despite initial fears or myths, Oracle RAC on AIX in Skytap, can be an easy to use and stable platform with an excellent recovery and DR implementation. Performance of disks in Skytap is one of the better ones you will see in cloud implementations and should generally be more than enough for your Oracle RAC implementations. One of the tests we did together with Skytap a few years ago when MAS was being introduced as a feature, showed that the disks’ performance is comparable and even better to a mid-to-high end implementation on site.
If you are interested in finding out more or working with us, contact us.
