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Making Sense Of Virtualization Availability Options

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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 3rd 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 3rd 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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SIOS Technology Spotlights 5 Myths about Cloud HA and DR

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SAN MATEO, CA – October 7, 2014 – Enterprises are moving more and more applications to the cloud.  The use of cloud computing is growing, and by 2016 this growth will increase to become the bulk of new IT spend, according to Gartner, Inc. 2016 will be a defining year for cloud as private cloud begins to give way to hybrid cloud, and nearly half of large enterprises will have hybrid cloud deployments by the end of 2017.

“While the benefits of the cloud may be clear for applications that can tolerate brief periods of downtime, for mission-critical applications, such as SQL Server, Oracle and SAP, companies need a strategy for high availability (HA) and disaster recovery (DR) protection,” said Jerry Melnick, COO of SIOS Technology Corp., maker of SAN and SANLess clustering software. “While traditional SAN-based clusters are not possible in these environments, SANLess clusters can provide an easy, cost-efficient alternative.”

According to Gartner, IT service failover automation provides end-to-end IT service startup, shutdown and failover operations for disaster recovery (DR) and continuous availability. It establishes ordering and dependency rules as well as IT service failover policies. The potential business impact of this emerging technology is high, reducing the amount of spare infrastructure that is needed to ensure DR and continuous availability, as well as helping ensure that recovery policies work when failures occur, thus improving business process uptimeii. Jerry Melnick says separating the truths and myths of HA and DR in cloud deployments can dramatically reduce data center costs and risks. He debunks these five myths:

Myth #1 – Clouds are HA Environments. Public cloud deployments, particularly with leading cloud providers, are high availability environments where application downtime is negligible.

  • The Truth – Redundancy is not the same as HA.  Some cloud solutions offer some measure of data protection through redundancy. However, applications such as SQL Server and file servers still need additional configuration for automating and managing high availability and disaster recovery.

Myth #2 – Protecting business critical applications in a cloud with a cluster is impossible without shared storage. You cannot provide HA for Windows applications in a cloud using Windows Server Failover Clustering (WSFC) to create a cluster because it requires a shared storage device, such a SAN. A SAN to support WSFC is not offered in public clouds, such as Amazon EC2 and Windows Azure.

  • The Truth – You can provide high availability protection for Windows applications in a cloud simply by adding SANless cluster software as an ingredient and configuring a WSFC environment. The SANless software synchronizes local storage in the cloud through real-time, block level replication, providing applications with immediate access to current data in the event of a failover.

Myth #3 – Remote replication isn’t needed for DR. Applications and data are protected from disaster in the cloud without additional configuration.

  • The Truth – Cloud providers experience downtime and regional disasters like any other large organization. While providing high availability within the cloud will protect data centers from normal hardware failures and other unexpected outages within an availability zone (Amazon) or fault domain (Azure), data centers still need to protect against regional disasters. The easiest solution is to configure a multisite (geographically separated) cluster within a cloud and extend it by adding an additional node(s) in an alternate datacenter or different geographic region.

Myth #4 – Using the cloud is “all or nothing.”

  • The Truth: Companies can use the on-premise datacenter as its primary datacenter and cloud as the hot standby DR site. DR configurations can be assembled from a single on-premise server that includes a remote cluster member hosted in the cloud. Or, the on-premise configuration could be a traditional SAN based cluster that includes a remote cluster member hosted in a cloud. Both approaches are very cost effective alternatives to building out a separate DR site, or renting rack space in a business continuity facility.

Myth #5 – HA in a cloud has to be costly and complicated.

  • The Truth: A cluster for high availability in a cloud can be easily created using SANless clustering software with an intuitive configuration interface that lets users create a standard WSFC in a cloud without specialized skills. SANless clustering software also eliminates the need to buy costly enterprise edition versions of Windows applications to get high availability and added disaster protection or as described in Myth 4, to eliminate the need to build out a remote recovery site.

iGartner Says Cloud Computing Will Become the Bulk of New IT Spend by 2016.(http://www.gartner.com/newsroom/id/2613015) iiGartner Hype Cycle for IT Service Continuity Management, 2014.  September 10, 2104.  Analysts:  John P Morency, Carl Claunch, Pushan Rinnen  About SIOS Technology Corp. SIOS Technology Corp. makes SAN and #SANLess software solutions that make clusters easy to use and easy to own.An essential part of any cluster solution, SIOS SAN and #SANLess software provides the flexibility to build Clusters Your Way™ to protect your choice of Windows or Linux environment in any configuration (or combination) of physical, virtual and cloud (public, private, and hybrid) without sacrificing performance or availability. The unique SIOS #SANLess clustering solution allows you to configure clusters with local storage, eliminating both the cost and the single-point-of-failure risk of traditional shared (SAN) storage. Founded in 1999, SIOS Technology Corp. (www.us.sios.com) is headquartered in San Mateo, California, and has offices throughout the United States, United Kingdom and Japan.

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Contact: Beth Winkowski Winkowski Public Relations, LLC for SIOS Phone: 978-649-7189 Email: bethwinkowski@us.sios.com

Disaster Recovery Journal: SIOS Spotlights 5 Myths about Cloud HA and DR

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SAN MATEO, Calif. – Enterprises are moving more and more applications to the cloud. The use of cloud computing is growing, and by 2016 this growth will increase to become the bulk of new IT spend, according to Gartner, Inc. 2016 will be a defining year for cloud as private cloud begins to give way to hybrid cloud, and nearly half of large enterprises will have hybrid cloud deployments by the end of 2017.

“While the benefits of the cloud may be clear for applications that can tolerate brief periods of downtime, for mission-critical applications, such as SQL Server, Oracle and SAP, companies need a strategy for high availability (HA) and disaster recovery (DR) protection,” said Jerry Melnick, COO of SIOS Technology Corp. (www.us.sios.com), maker of SAN and SANless clustering software. “While traditional SAN-based clusters are not possible in these environments, SANless clusters can provide an easy, cost-efficient alternative.”

According to Gartner, IT service failover automation provides end-to-end IT service startup, shutdown and failover operations for disaster recovery (DR) and continuous availability. It establishes ordering and dependency rules as well as IT service failover policies. The potential business impact of this emerging technology is high, reducing the amount of spare infrastructure that is needed to ensure DR and continuous availability, as well as helping ensure that recovery policies work when failures occur, thus improving business process uptimeii.

Jerry Melnick says separating the truths and myths of HA and DR in cloud deployments can dramatically reduce data center costs and risks. He debunks these five myths:

Myth #1 – Clouds are HA Environments. Public cloud deployments, particularly with leading cloud providers, are high availability environments where application downtime is negligible.

  • The Truth – Redundancy is not the same as HA.  Some cloud solutions offer some measure of data protection through redundancy. However, applications such as SQL Server and file servers still need additional configuration for automating and managing high availability and disaster recovery.
  • The Truth – You can provide high availability protection for Windows applications in a cloud simply by adding SANless cluster software as an ingredient and configuring a WSFC environment. The SANless software synchronizes local storage in the cloud through real-time, block level replication, providing applications with immediate access to current data in the event of a failover.

Myth #2 – Protecting business critical applications in a cloud with a cluster is impossible without shared storage.You cannot provide HA for Windows applications in a cloud using Windows Server Failover Clustering (WSFC) to create a cluster because it requires a shared storage device, such a SAN. A SAN to support WSFC is not offered in public clouds, such as Amazon EC2 and Windows Azure.

Myth #3 – Remote replication isn’t needed for DR. Applications and data are protected from disaster in the cloud without additional configuration. 

  • The Truth – Cloud providers experience downtime and regional disasters like any other large organization. While providing high availability within the cloud will protect data centers from normal hardware failures and other unexpected outages within an availability zone (Amazon) or fault domain (Azure), data centers still need to protect against regional disasters. The easiest solution is to configure a multisite (geographically separated) cluster within a cloud and extend it by adding an additional node(s) in an alternate datacenter or different geographic region.
  • The Truth: Companies can use the

Myth #4 – Using the cloud is “all or nothing.”

Myth #5 – HA in a cloud has to be costly and complicated.

  • The Truth: A cluster for high availability in a cloud can be easily created using SANless clustering software with an intuitive configuration interface that lets users create a standard WSFC in a cloud without specialized skills. SANless clustering software also eliminates the need to buy costly enterprise edition versions of Windows applications to get high availability and added disaster protection or as described in Myth 4, to eliminate the need to build out a remote recovery site.

iGartner Says Cloud Computing Will Become the Bulk of New IT Spend by 2016.(http://www.gartner.com/newsroom/id/2613015)

iiGartner Hype Cycle for IT Service Continuity Management, 2014.  September 10, 2104.  Analysts:  John P Morency, Carl Claunch, Pushan Rinnen

About SIOS Technology Corp.

SIOS Technology Corp. makes SAN and #SANLess software solutions that make clusters easy to use and easy to own.An essential part of any cluster solution, SIOS SAN and #SANLess software provides the flexibility to build Clusters Your Way™to protect your choice of Windows or Linux environment in any configuration (or combination) of physical, virtual and cloud (public, private, and hybrid) without sacrificing performance or availability. The unique SIOS #SANLess clustering solution allows you to configure clusters with local storage, eliminating both the cost and the single-point-of-failure risk of traditional shared (SAN) storage.

Founded in 1999, SIOS Technology Corp. (www.us.sios.com) is headquartered in San Mateo, California, and has offices throughout the United States, United Kingdom and Japan.