Friday Feb 28, 2014

Friday Spotlight: What's in a Name?

This week’s spotlight is an Oracle VM tip from Greg King, our best practices engineer. While the tip may appear to be straightforward, a well thought out naming convention is critical in helping system administrators better organize, manage and eliminate mistakes made by other administrators.

Oracle VM is designed to be a highly availability computing platform for your Oracle VM guests. However, high availability is not just about ensuring you have eliminated as many single points of failure as possible, it also means making your Oracle VM platform easy to understand and maintain. An easy to understand Oracle VM environment makes all the difference in managing and maintaining a fault tolerate environment for your Oracle VM Guests when the chips hit the fan.

The use of meaningful descriptions and simple names is a frequently overlooked key to maintaining a reliable highly available computing platform. One goal of high availability is reducing the occurrence of mistakes that cause outages through human error. Using cryptic naming schemes, relying on default names of objects and failing to use descriptions effectively all contribute to overly complex, hard to understand Oracle VM environments; this in turn can completely undermine all the effort you put into eliminating single points of failure in your hardware and operating systems.

The easier it is to understand things at a glance, the faster tasks can be done with less explanation and less chance for critical mistakes. So, let’s take a look at a few examples of things you can do to make your Oracle VM object naming scheme more powerful.

People often leave the simple name for the server management network as the dotted decimal notation of the subnet. Even worse, they use the dotted decimal subnets as names for all their other networks they create. This is pretty cryptic and quite meaningless to anyone but a few in your organization. The default name is meant to be changed to something meaningful in your environment and a naming scheme should be developed that is simple yet meaningful for the remaining networks you create. We have a network naming white paper available on OTN that might give you some good ideas.

You should also take the time to create meaningful naming schemes for Oracle VM servers, server pools, physical disks, virtual disks, guests and guest resources such as assemblies, ISO images and templates. You want to be able to relate various objects to each other without having to search through different tabs and sub-tabs so take the time to create and use meaningful simple names.

If nothing else, the more time you spend making your naming scheme easy to understand, the faster you can detect issues from Oracle VM Manager at a glance. This can save you time on maintaining tedious documentation that you don’t like to write and most people don’t like to read.

Tuesday Dec 17, 2013

Telco Case Study: "IT-as-a-Service" with Oracle VM Enables Higher Business Availability

In this blog article we want to share with you a use case for Oracle VM enabling high availability through an "IT-as-a-Service" deployment at a Telco provider.

Using Oracle VM, the Telco customer is able to realize a highly efficient server infrastructure to dynamically provision and reclaim resources to quickly respond to business demands. With over 100 Oracle Real Application Clusters (RAC) servers deployed in an Oracle VM-based virtualized environment, the Telco customer has a solid, highly available infrastructure designed for maximum flexibility.

To better respond to the customer needs for application services, the Telco customer uses Oracle VM Templates to roll out new servers, each taking only 10 minutes per box which can be ready in parallel. “It’s all cabled once, it’s all in a pool, and we have created processes and procedures to quickly add more resources as we need them. Oracle VM provides this elasticity.” says the Telco architect.

Read the whitepaper and get an in-depth look at "IT-as-a-Service" deployment at a large Telco.

Monday Nov 08, 2010

Deploy A Highly Available Virtualized Infrastructure with Oracle VM and Oracle RAC

Join us for a live webinar on Tuesday, Nov. 16th at 9am US PT as we discuss how the combination of Oracle VM server virtualization and Oracle Real Application Clusters (RAC) enables the benefits of a virtualized data center infrastructure for highly available applications.

In this session we will cover technical details of how to use and deploy Oracle RAC in an Oracle VM environment, and create a production ready multi-node virtual environment in a fully automated way. Attend this session to understand how you can benefit from the most highly-available, grid-ready combination of Oracle VM and Oracle RAC.

Get more info and register here.

 


Tuesday Jul 20, 2010

Improve Application Uptime and High Availability with Oracle VM

Join Oracle VM experts for a live webinar and find out how you can improve your application uptime and high availability. Oracle VM offers a variety of high availability features to ensure that business critical uptime is maximized. In this webinar, we will address how Oracle VM can help you:


  • Achieve higher levels of availability in your data center

  • Eliminate unplanned service outages and reduce downtime

  • Securely migrate running VMs without service interruption

  • Achieve failover redundancy and optimal resource utilization of pool hardware

Technical demonstrations of a number of concepts including shared storage pools, secure live migration, failover and automatic restart of a VM, will be covered in this session.

Details:
Day: July 28, 2010
Time: 9am US PDT

Register here.

Hope you will join us.

Monica

Tuesday Apr 21, 2009

Oracle VM High Availability - Hands-on Guide to Implementing Guest VM HA

We just released a new White Paper: Oracle VM High Availability – Hands-on Guide to Implementing Guest VM HA. Guest VM HA functionality provides a powerful, easy-to-manage solution for maximizing up-time for virtually any guest VM workload, without requiring any tailoring inside the VM, making it simple to set-up, use, and maintain.

This white paper focuses on best practices of the Oracle VM Guest VM High Availability (HA) design and implementation. It's complementary to the previous White Paper: Oracle VM – Creating & Maintaining a Highly Available Environments for Guest VMs, and serves as a practical guide to help customers design the HA environment and experience the benefits of Oracle VM. It provides a step-by-step guide to plan and set up the Oracle VM environment so you can implement the guest VM HA feature to assure predictable, reliable, and accurate restarting of failed VM and Servers.

To implement HA, you must create a cluster of Virtual Machine Servers in a server pool and have them managed by Oracle VM Manager or Oracle Enterprise Manager Grid Control. Some basic steps include:

1. Installing Oracle VM Server and Manager
2. Creating Shared Storage for the Server Pool
3. Enabling HA for the Server Pool
4. Adding a new Server to the Server Pool
5. Enabling HA for the Virtual Machines

The most important part is to create shared storage for the server pool. You can set up shared storage for the server pool in the following configurations:

* OCFS2 (Oracle Cluster File System) using the iSCSI (Internet SCSI) network protocol
* OCFS2 using SAN (Storage Area Network)
* NFS (Network File System)

The procedures for creating shared storage for HA are essentially the same as what's described in the Oracle VM Server User Guide for creating a shared virtual disk using the above storage configurations for live migration. But you have fewer steps to go through when creating shared storage for HA. For example, you don't need to manually modify /etc/fstab for enabling HA since the configuration files will be handled by Oracle VM server agent automatically when you run /usr/lib/ovs/ovs-makerepo utility. In addition, the startup of related cluster services (o2cb) will also be handled when you run /usr/lib/ovs/ovs-cluster-configure utility.

One of the common mistakes is that when the network is not configured properly, the cluster configuration files such as /etc/ocfs2/cluster.conf won't be propagated correctly to each server of the server pool. For example, the loopback address (127.0.0.1) may show up in the /etc/ocfs2/cluster.conf for some servers. You should verify your network settings (DNS, routing table, etc.), replace the loopback address with the public IP address for each server and make sure that the ocsf2 cluster configuration file (/etc/ocfs2/cluster.conf) be the same across all the servers within the same pool.

In summary, Oracle VM Guest VM HA functionality provides the following benefits:

* Auto-restart unexpectedly failed individual VMs on other servers in the server pool;
* Auto-restart all the guest VMs on another server in the server pool when an unexpected physical server failure occurs;
* Powerful cluster-based network- and storage heartbeat algorithms quickly and deterministically identify failed and/or isolated servers in the server pool to ensure rapid, accurate recovery;
* Sophisticated distributed lock management functionality for SAN, NFS, NAS, and iSCSI storage ensures VMs or entire servers can be rapidly restarted with no risk of data corruption.

For more information about Oracle VM and how customers are deploying it, please visit
http://oracle.com/virtualization.

Friday Apr 03, 2009

Oracle VM: Part 3 - Where Does Guest VM HA Fit-in Versus Other HA Software: HA Cluster Software and Guest VM HA

This is part 3 of my series on HA techniques up-and-down the stack and how they relate to use of Oracle VM’s Guest VM HA features. This installment talks about HA cluster software or “clusterware”. For databases, of course, Oracle RAC is the ultimate, but what about HA for database or other workloads where you might be using clusterware? Even with databases, you may not require continuous availability or you may not require the ability to support a workload that is greater than the capacity of a single physical server. In that case, having a fail-over based model where there may be some very short outage before automatic resumption of service is probably acceptable - clusterware is probably a good solution. But, wait, doesn’t it seem like HA implemented at the guest VM level would work in this situation as well? The answer is yes, but they are not totally identical in capabilities to let’s examine those a bit.

HA clusterware software runs inside the guest itself while guest VM HA solutions from the major vendors, including Oracle, execute outside the VM itself. In other words, the HA clusterware is generally application- or application-service aware: it knows what is running, maybe even down to the process level and can monitor each individual registered service. As a result, it has the advantage that it can do things like selectively restart specific services without requiring a restart of the node. It is a better position to do hang detection more quickly and to potentially resolve issues at a finer-grained level: why reboot the whole machine if, say, the OS is healthy, but the web server is hung for some reason? Much better to just restart the web server. From the outside, it is very hard to detect even an OS hang consistently (a node may appear to be “running” when, in reality, it has ceased performing productive work and would need to be restarted). And it is essentially impossible to detect the hang of one individual service or application without some specific, intrusive integration. But clusterware like Oracle’s generally has sophisticated hang detection capability to permit a rapid restoration of service(s). It is this finer-grained “application/service awareness” that is a key strength of clusterware above what guest VM HA restarts from the virtualization layer can provide.

At this point in these series of blog entries, you may be wondering about the value of implementing HA at the virtualization layer if I’m saying that it does not provide continuous availability (like RAC) and it is not explicitly application aware (like clusterware), but the case for guest VM HA is actually quite strong. The reality is that today anyway, the products available up the stack (from any vendor) typically provide their benefits at the cost of configuration complexity and likely licensing fees* (*not always...see below) beyond the cost of the virtualization layer and thus those benefits need to be weighed against the costs.

Many scenarios absolutely justify the cost and effort for implementing these powerful HA solutions for mission-critical applications, but, equally, there are likely a large number of server instances of all types where it is definitely desirable to automatically restart the server/VM instance should it fail (especially at 3am Sunday morning after a night out!), but where you do not want to incur the costs of implementing HA software up the stack (costs of all types…learning/training, configuration/maintenance complexity, support costs, licensing costs, etc). For these scenarios, HA implemented in the virtualization layer is ideal because it will automatically restart failed nodes but has absolutely minimal complexity for the admin creating the virtual machine: typically just checking a box to enable the HA functionality for that VM and you are done. No adding HA agents or setting up HA services or registering applications. It just works.

*One final note on the more commercial aspects of this for Oracle customers: licensing expense. Oracle is unique amongst virtualization vendors in that we offer enterprise class software not only at the virtualization layer but also a portfolio of software that runs inside the VMs, including key infrastructure like Clusterware. Oracle VM, including Oracle VM Manager is free: no license expense so you only pay for annual support. Similarly, Oracle Clusterware is also included in the support fee when purchase an Unbreakable Support subscription for Enterprise Linux or if you are using the Clusterware to support an Oracle database. This is powerful, enterprise class HA at a bargain price. Not only no license fee, but even comparing Oracle’s support pricing for these products with the support pricing for equivalent products from other vendors, you would find this to be incredibly affordable.

The conclusion in this series is that all of these techniques have a vital role to play and that no one of them eliminates the need for the other despite what other vendors would try to have you believe. In fact, these are solidly complementary techniques that can work very well together to further improve the availability of your stack from top-to-bottom. And an advantage of working with Oracle is that we can work with you across all these options to tailor the best solution for you.

Thursday Mar 26, 2009

Part 2: Where Does Guest VM HA Fit-in Versus Other HA Software: RAC and Guest VM HA

As part 2 in this series of blog entries about HA techniques in a virtualized environment, I’m going to focus on considerations when thinking about using Oracle Real Application Clusters (RAC) with- (or without) Oracle VM HA. For databases, Oracle RAC is the ultimate: Continuous availability and ability to handle workloads that are larger than what a single physical server can handle. If you need continuous uptime for your database applications, then you need RAC. Others are claiming that a single instance database with their flavor of clusterware or with their flavor of virtualization is equivalent to RAC. Ummm…No. Sorry: That is a terrible blurring of lines to force-fit the wrong solution. Again, the question is, do you need continuous availability? No one’s guest VM HA or clusterware solution provides continuous availability in a way that is practical for production databases today except RAC. Period*. (I’ll get a comment or two for that statement but let me get to that in a minute). Even if you don’t need continuous availability, do you need to support database workloads greater than a single physical (or virtual) machine could support? If so, again, you need RAC. No one’s clusterware or virtualization-based HA can do that today. So, if faced with these claims just ask two very simple questions:
1. Will that give me continuous availability?
2. Will that allow workloads that will scale larger than a single physical node?
If the answer to either one is “no”, then it is not equivalent to RAC and they are trying to fool you.

*On that continuous availability thing…OK…so there are some projects and some vendors starting to claim they have a “fault tolerant” or “continuous availability” mode for their virtualization product here or coming soon, but these are no where near ready for production use. These appear to be uniprocessor-only, very slow, and unproven in the reliability of their methodology for assuring there will be no corruption…these are simply not ready to host things like databases and not yet even worth talking about for use in the “real world”. Someday, the technology may get there but when that changes, then I’ll blog about that. Also, no flames/comments from the proprietary hardware crowd on how they’ve been doing fault tolerant stuff since before I was born and before wood was invented or whatever. That stuff was/is great, but this blog is about virtualization on industry standard components that are about the only stuff mere mortals can afford these days.

Now let’s get back to positioning HA techniques in the stack. What about using RAC and HA at the virtualization layer, i.e. with guest VM HA / auto-restart enabled? There is definitely some value here. Virtualization, by definition, abstracts you from many of the constraints of the underlying hardware meaning it allows you to do things like automatically restarting a node on different, healthy hardware when the original hardware fails. In this scenario, if you have a physical server failure that takes down a node, the RAC database will continue service based on the surviving nodes, while, in parallel, Oracle VM Guest HA will restart the VM (RAC node) hosted on the failed physical server on another, healthy server in the pool. The node can then quickly and automatically rejoin the RAC cluster, bringing it to full capacity faster than any manual process. One thing to keep in mind is that you should specify what is known as “Preferred Server Policies” for your RAC nodes (VMs) in such a way as to prevent two RAC VMs from the same instance being hosted on a single physical server at any time to assure the best performance and service levels.

So that’s Oracle VM Guest HA and Oracle RAC. In the next installment in this series on HA, we’ll discuss the more general (i.e. non-database specific) case of HA cluster software and how it compares and complements Oracle VM Guest HA.

And, by the way, if you want to read a whitepaper on RAC and Oracle VM, go here and find it in the "Whitepapers" section.

Friday Mar 20, 2009

Where Does Guest VM HA Fit-in Versus Other HA Software? Part 1: About Guest VM HA

Customers ask us about Oracle VM and its guest HA / auto-restart functionality in the context of how it is best used in relation to other HA technologies available “up the stack” and I thought that it might be useful to share the discussion here over a couple of blog entries. This is the first entry in that series. This installment is about providing some context and then a summary of how the Guest VM HA / auto-restart feature works in Oracle VM.

Oracle Real Application Clusters (if you are using a database), Oracle Clusterware, and Oracle VM Guest HA are all available choices for users in implementing a highly available environment so how should they think about the best way to leverage these in their production enterprise? This is an especially important topic because some vendors like VMware or others that have only one part of this…say, only the guest VM restart features, or only the HA clusterware…are anxious to position their solution as THE complete solution when that is just not the case. As with many things in IT, it depends on what you are doing.

For context, and for those of you not familiar with the details on these products/features and Oracle VM’s Guest HA features, there are some whitepapers to look at on the Oracle Technology Network (OTN) page for Oracle VM (look for the Guest VM HA paper but also the paper on using Oracle RAC on Oracle VM and on using Oracle Clusterware to make Oracle VM Manager highly available…). I won’t go into all the details here except to summarize that Oracle VM has embedded portions of the OCFS2 clusterware stack into Oracle VM Manager to basically make the server pools into HA clusters and automatically restart VMs after a server or VM failure. Since this is sophisticated clusterware and not just the ICMP-based “pingware” that many other virtualization products offer, Oracle VM does an excellent, very deterministic job of detecting true failures and restarting accurately and cleanly without a lot of guessing as to the status of the VM.

For example, we perform not only network heartbeating but also disk-based heartbeating to enable more robust failure detection. And then we do distributed lock management on the storage to make sure there is no chance of data corruption in restarting a VM after declaring it failed. So aside from the fact that this is more sophisticated than the vast majority of guest VM HA solutions out there that don’t run a heartbeat on the disk, and that maybe only perform basic reserve release on the storage, the nice thing about the implementation is that it is super easy to make a VM highly available: just check a box. Truly. Yes, the clusterware is there under the covers, but the user creating the VM is not exposed to that so no agents to install, no services to register…just check the Enable HA box when you create the VM and you are done.

Over the course of a couple additional blog entries, we’ll walk through some considerations to help you decide which techniques provide the best total solution in your environment. Luckily, the considerations are pretty clear, with each product having a distinct set of considerations. Yes, we are Oracle, so of course we’ll speak to some considerations that are specific to the database, but most of this applies generically to any workload. The next blog entry in this HA series will be about RAC and Guest VM HA and should come out in the next few days so keep an eye out for that.

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