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Step-By-Step: Configuring A 2-Node Multi-Site Cluster On Windows Server 2008 R2 – Part 2

January 22, 2018 by Jason Aw Leave a Comment

Integrate Storage Replication With Failover Clustering

In Part 1 of this series, we took a look at the first steps required for building a multi-site cluster. We got to the point where we had a two node cluster that used a node and file share majority quorum, with no resources yet defined.

Let’s Continue

In this section we will start where we left off and look at how your replication solution will integrate with your failover clustering. Because each vendor’s replication solution will be implemented differently, it is hard to have one document that describes them all. The important thing to remember is that you want to purchase a replication solution that integrates with failover clustering and is certified by Microsoft. Your choices are basically array based, appliance based or host based replication solutions. EMC makes both appliance-based and array-based replication solutions and seem to do a great job at both. EMC’s John Toner maintains a blog that is dedicated to Geographically Dispersed Clusters and if you are going the EMC route, I’m sure he could lead you in the right direction. All the major vendors have solutions, you will just need to contact them to get the details.

SIOS DataKeeper

For this demonstration, I’m going to use a host based replication solution, SteelEye DataKeeper Cluster Edition, from my company, SteelEye Technology. It is so easy, that I thought instead of doing a long article, I would just record the steps and share it with you in a video. One of the advantages of host based replication is that you can utilize your existing storage, whether it is just some local attached disks, iSCSI or an expensive SAN. Host based replication can replicate across any storage devices.

Here is a summary of what you will see in the video.

Launch the SteelEye DataKeeper MMC Snap-in
- Create a new DataKeeper job, define mirror end points, network, compression, etc.
Launch the Failover Cluster MMC Snap-in
- Create a Hyper-V resource
- Add a DataKeeper Volume Resource
- Edit the properties of the DataKeeper Volume resource to associate it with the mirror created earlier
- Make the Virtual Machine configuration dependent upon the new DataKeeper volume resource

That’s it! You are now done. Sit back and enjoy your new Hyper-V multi-site cluster.

CLICK TO WATCH VIDEO

In Part 3 of this series, we will tackle SQL 2008 multi-site clusters on Windows Server 2008 R2. There are a few more steps and some tips and tricks you will definitely need to know, so make sure you check back to get all of the details. In the meantime, if you need assistance, leave me a comment or contact me through SIOS and I’d be glad to help you out.

Reproduced with permission from https://clusteringformeremortals.com/2009/09/18/step-by-step-configuring-a-2-node-multi-site-cluster-on-windows-server-2008-r2-%E2%80%93-part-2/

Making Sense Of Virtualization Availability Options

January 21, 2018 by Jason Aw Leave a Comment

What Are The Virtualization Availability Options?

Microsoft Windows Server 2008 R2 and vSphere 4.0 are newly released. Let’s take a look at some Virtualization Availability Options when considering the availability of your virtual servers and the applications running on them.

I also will take this opportunity to describe some of the features that enable virtual machine availability. Additionally, I have grouped these features into their function roles to help highlight their purpose.

Planned Downtime

Live Migration and VMware’s VMotion are both solutions that allow an administrator to move a virtual machine from one physical server to another with no perceivable downtime. There is one key thing to remember. The move must be a planned event in order to move a virtual machine from one server to another without any downtime. A planned event is that the virtual machine’s memory is synchronized between the servers, before the actual switchover occur. This is true of both Microsoft’s and VMware’s solutions. Also keep in mind that both of these technologies require the use of shared storage to hold the virtual hard disks (VMDK and VHD files), which limits Live Migration and VMotion to local area networks. This also means that any downtime planned for the storage array must be handled in a different way. Important to note if you want to limit the impact to your virtual machines.

Unplanned Downtime

Microsoft’s Windows Server Failover Clustering and VMware’s High Availability (HA) are solutions that are available to protect virtual machines in the event of unplanned downtime. Both solutions are similar. They monitor virtual machines for availability. The VMs are moved to standby node if there is a failure. Then, the machines are rebooted for this recovery process. There was no time to sync the memory before failover.

Disaster Recovery

How do I recover my virtual machines in the event of a complete site loss? The good news is that virtualization makes this process a whole lot easier. A virtual machine is simply a file that can picked up and moved to another server. Up to this point, VMware and Microsoft are pretty similar in their availability features and functionality. However, here is where Microsoft really shines. VMware offers Site Recovery Manager which is a fine product. But is limited in support to only SRM-certified array-based replication solutions. Also, the failover and failback process is not trivial and can take the better part of a day to do a complete round trip from the DR site back to the primary data center. It does have some nice features like DR testing. In my experience with Microsoft’s solution for disaster recovery they have a much better solution when it comes to disaster recovery.

Microsoft’s Hyper-V DR solution

Microsoft’s Hyper-V DR solution is Windows Server Failover Clustering in a multi-site cluster configuration (see video demonstration). In this configuration, the performance and behavior is the same as a local area cluster, yet it can span data centers. Essentially, you can actually move your virtual machines across data centers with little to no perceivable downtime. Failback is the same process, just point and click to move the virtual machine resource back to the primary data center. There is no built-in “DR Testing”. Although I think it is preferable to do an actual DR test in just the matter of a minute or two with no perceivable downtime.

Host-Based Replication Vendors

One other thing I like about WSFC multi-site clusters is that the replication options include not only array-based replication vendors, but also host-based replication vendors. This really gives you a wide range of replication solutions in all price ranges and does not require that you upgrade your existing storage infrastructure.

Fault Tolerance

Fault tolerance basically eliminates the need to reboot a virtual machine in the event of an unexpected failure. VMware has the edge here in that it offers VMware FT. There are a few other 3^rd party hardware and software vendors that play in this space as well. There are plenty of limitations and requirements when it comes to implementing FT systems. This is an option if you need to ensure a hardware component failure results in zero downtime vs. the minute or two it takes to boot up a VM in a standard HA configuration. You probably want to make sure that your existing servers are already chock full of hot standby CPUs, RAM, power supplies, etc. And you have redundant paths to the network and storage. Otherwise you may be throwing good money after bad. Fault tolerance is great for protection from hardware failures. What happens if your application or the virtual machine’s operating system is behaving badly? That is when you need application level clustering as described below.

Application Availability

Everything I have discussed up to this point really only takes into consideration the health of your physical servers and your virtual machines as a whole. This is all well and good, however, what happens if your virtual machine blue screens? Or what if that latest SQL service pack broke your application? In those cases, none of these solutions are going to do you one bit of good. For those most critical applications, you really must cluster at the application layer. Look into clustering solutions that run within the OS on the virtual machine vs. within the hypervisor. In the Microsoft world, this means MSCS/WSFC or 3^rd party clustering solutions. Your storage options, when clustering within the virtual machine, are limited in scope to either iSCSI targets or host-based replication solutions. Currently, VMware really does not have a solution to this problem. It would defer to solutions that run within the virtual machine for application layer monitoring.

Summary

With the advent of virtualization, it is really not a question of if you need availability. And more of a question of what Virtualization Availability Options will help meet your SLA and/or DR requirements. I hope that this information helps you make sense of the availability options available to you.

Reproduced with permission from https://clusteringformeremortals.com/2009/08/14/making-sense-of-virtualization-availability-options-2/

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Steeleye Datakeeper Cluster Edition Wins Windows It Pro Best High Availability/Disaster Recovery Awards

January 20, 2018 by Jason Aw Leave a Comment

I am pleased to announce that Windows IT Pro has awarded SteelEye DataKeeper Cluster Edition the Best High Availability and Disaster Recovery Product in two categories; Community Choice Gold Award and Editors’ Best Silver Award.

I am really proud to be a part of the SteelEye DataKeeper team and I appreciate all of the Windows IT Pro community that voted for us in the Community Choice award!

Reproduced with permission from https://clusteringformeremortals.com/2009/11/20/steeleye-datakeeper-cluster-edition-wins-windows-it-pro-best-high-availabilitydisaster-recovery-awards/

Tech Target – Search Disaster Recovery: Cayan DR goes ‘from zero to 60’ with DataKeeper SANless mirror

February 12, 2015 by Margaret Hoagland

Using DataKeeper software, Online transaction processing firm Cayan sets up mirror sites for ‘quasi active-active’ servers that facilitate rapid failover.

Online credit card transaction company Cayan set up effective disaster recovery/high availability using only its Windows Server and DataKeeper software or for asynchronous replication between two sites.

Boston-based Cayan, which changed its name from Merchant Warehouse in January, helps companies complete customer transactions through options such as online purchases, mobile payments and ApplePay.

Cayan’s business requires that it stay online without exception, so high availability is as important as recovery from a large disaster. The firm uses Microsoft Windows Server as storage for the SQL database that its customer engagement system runs on. After experimenting with Microsoft’s native replication but finding it to be too much work, Cayan avoided buying a SAN by installing SIOS Technologies DataKeeper Cluster Edition software. DataKeeper works with Windows Server Failover Clustering (WSFC) to protect data through real-time block-level replication.

Cayan began testing DataKeeper in late 2013 and put it in production in 2014. At the time, it added a co-location site provided by CenturyLink as part of a data center upgrade. The company uses DataKeeper to asynchronously replicate between databases at its Waltham, Massachusetts, facility and a mirror colocation site in Oak Grove, Illinois.

The secondary site is passive, but Cayan is testing what CTO Paul Vienneau calls a “quasi active-active” setup for load balancing, enabling live traffic at both sites. The database node will be active at one site, and all traffic will go to that site. If the active site goes down, its SQL Server node will fail over to the other site in less than a minute, Vienneau said.

“If the primary database node is in Waltham, the traffic that goes into Oak Grove will be re-directed from the application servers that sit in Oak Grove across the WAN to the database server in Waltham,” Vienneau said. “That gives us minimal [recovery time] there as far as getting back up. If there’s a disaster scenario in Waltham, the SQL server failover will take in 30 seconds and we’ll be live in the Oak Grove site. Because both sites are quasi-active, there’s not a lot of heavy lifting other than the database failing over, and away we go.”

Vienneau said Cayan is in the final stages of testing that setup and will soon go live.

Even without the active-active setup, DataKeeper’s replication makes for quicker recovery than Cayan had before. Vienneau said it could take hours to restore his database the old way when Cayan relied on a Rackspace managed service.

“There wasn’t any of what I call a plausible DR strategy,” he said. “We built this from the ground up when we moved out of Rackspace to CenturyLink. We went from zero to 60 with our HA and DR strategy.”

Vienneau said Cayan hasn’t had any disasters since using DataKeeper but “we’ve tested considerably.”

Vienneau calls his set up high availability instead of only DR “because we can set up fairly quickly in the Oak Grove site, so you can think of it has geo-diverse HA. We have redundancy throughout the entire stack. Because DataKeeper keeps both sites in sync at any point in time and because we can minimize failover, we have two data centers acting as HA.”

“It’s not a traditional DR where your recover time is two hours. It’s taking us less than a minute. We can make it seamless for the end user. They might see a little lag where the cut over is taking place, but they’re not seeing any loss of transactions.”

Those end users consist mostly of small businesses that rely on Cayan to process their credit card transactions.

“We’re a 24/7/365 shop,” he said. “We’re not afforded a lot of downtime. We process over $100 billion in credit card transactions a year. If we’re down a couple of hours, it’s not good for us our merchants.”