SRM is a tool, not a goal

“Technically almost everything is possible.” One of the first things I will say to a customer when they ask advice about IT related stuff. This is also true with Site Recovery Manager (SRM), an excellent tool for enabling Disaster Recovery within your vSphere environment.

And the focus here is on “for enabling”. SRM is a means to an end. SRM is a tool and not a goal. It al starts with the definition what needs to be protected. Most of the times SRM is already bought and paid for, but during the implementation the question comes up : “What do we need to protect?”.

This is the other way around. It the same as building a house, but you don’t know how many people need to live in it. It must start with a definition what needs to be protected. What do you want to be failed over in case of disaster. In what time do you want this to happen? And how much data loss do you consider acceptable?

These are just a few questions that need to be answered before building your Disaster Recovery solution. Thankfully VMware has created a book on this topic with the title “A Practical Guide To Business Continuity & Disaster Recovery”.

The picture above is from this book and defines the process that needs to be followed when implementing a DR solution. In companies where IT processes have been defined, for example by using ITIL, “Business Process” most of the times is already there. You can find the answers to you questions in Service Level Agreements (SLA) or other documents that define the agreements between the business and the IT department with regards to application requirements.

Next is to define the applications that need to be protected by your DR solution. And especially insight needs to be created in the application chain. Most applications are depended on other applications for doing their job. So in case of a disaster it would be nice to have the complete application chain, in stead of just the web frontend. Products like VMware Infrastructure Navigator are nice tools to show these applications dependencies and to give you an overview of your applications chains.

After gathering this information the implementation of SRM is pretty straight forward. You can easily define your recovery plans and make sure that all virtual machines that need to be protected are identified and replicated to the recovery site.

Think first, build later… That’s what it all comes down to with SRM!

Understanding vSphere stretched clustering and SRM

Stretched clustering is one of the challenging topics I get when meeting with customers. Many customers think that stretched clustering is the ultimate disaster recovery solution and that it makes SRM obsolete. This is due to the fact that people think that HA will solve all their problems when it comes down to DR and that they still have the advantage of vMotion to have workload mobility between two data centers.

This however isn’t always true and there are some catches to the implementation of stretched clusters. In some cases, depending on the customers requirements, it even is better to have an SRM implementation to fulfill the requirements.

The table below give a graphical representation of which solution best suits which requirement.

So in the end its up to the customer to decide which solution best suits its requirement. To help make this decision VMware Tech Marketing created a whitepaper to help make the right choice. A must read for everybody involved with disaster recovery and availability within a vSphere infrastructure.

The whitepaper can be found here.

VMware SRM and EMC Symmetrix

Lately I’ve been working on a VMware Site Recovery Manager (SRM) 4.1 implementation in combination with a the Symmetrix storage arrays by EMC. Designing and figuring out how to get SRM working in combination with the storage arrays is the hard part of the job.

It requires knowledge of SRM, the EMC storage arrays and the vSphere infrastructure that you are implementing SRM into. The hard part is in the connection between SRM and the storage arrays. EMC providers a Storage Replication Adapter (SRA) , the EMC SRDF adapter, to integrate SRM with the Symmetrix storage arrays.

You need to understand how the SRA works, how to get it to working in combination with the Solutions Enabler software and how to present the replicated LUNs to your SRM.

EMC has written a document, “Using EMC SRDF Adapter for VMware vCenter Site Recovery Manager”, to fully understand all the software tooling and components involved in setting up a SRM implementation in combination with Symmetrix storage arrays.

The document is divided into four chapters and two appendices:

Chapter 1, “Introduction to VMware Technology,” introduces the reader to VMware and its technologies.

Chapter 2, “Installation and Configuration,” discusses the installation, setup and configuration of the EMC SRDF Storage Replication Adapter for VMware vCenter Site Recovery Manager version 4. This chapter also presents detailed best practices for installing and configuring Solutions Enabler for management of Symmetrix storage arrays.

Chapter 3, “Testing Recovery Plans with SRDF Adapter version 2.2,” presents how to configure and execute recovery plans with SRM version 4 and EMC SRDF Adapter version 2.2.

Chapter 4, “Failover and Failback with SRDF Adapter version 2.2,” discusses how to configure and execute failover and failback operations with SRM version 4 and EMC SRDF Adapter version 2.2.

Appendix A, “Symmetrix Access Controls with EMC SRDF Adapter,” discusses how to use Symmetrix Access Controls to manage access and control of the Symmetrix storage arrays visible to the VMware vCenter Site Recovery Manager server.

Appendix B, “Solutions Enabler Licensing,” discusses how to license Solutions Enabler to make use of the EMC SRDF SRA features. This section includes pre-Solutions Enabler 7.2 host-based licenses as well as Solutions Enabler 7.2 Symmetrix-based eLicensing.

Hopefully this document will help others understand SRM better and to successfully implement SRM with EMC Symmetrix storage arrays. It helped me in getting the job done! Thanks EMC.

HDS SRA 2.0

If you want VMware SRM to work with your storage array it needs to communicate to the storage array. For this reason each storage vendor has created a Storage Replication Adapter (SRA) which plugs into SRM. You can download these SRAs for each vendor here. (Note : Only download from the VMware website. Why?)

HDS also provides a SRA to connect to its storage arrays. But only installing the SRA won’t get the storage array to be recognized by SRM. The picture below gives a graphical representation of the component needed to let SRM communicate with the HDS storage array.

Click on picture to enlarge

The HDS SRA 2.0 needs an instance of the HDS Command Control Interface (CCI) to communicate to the HDS storage array. The HDS CCI is storage box management software which is provided by HDS. This can be installed on the SRM server next to SRM and the SRA.

To create an instance of the HDS CCI a Hitachi Online Remote Copy Manager (HORCM) service is defined manually on the Windows host. The HDS CCI manages the storage array(s) through the defined control LUNs on each storage array. The HORCM service is configured in the HORCM file. This file defines which LUNs are replicated between the protected and the recovery site. These LUNs are the LUNs that SRM can see and which it can managed for Disaster Recovery and testing purposes.

During configuration the HDS SRA is pointed to the HORCM instance which manages the storage array(s). All this provides the HDS SRA with the information which it passes through to the SRM server.

This creates the connection between the SRM server and the storage array necessary for SRM to work. For more information look at the VMware vCenter Site Recovery Manager Deployment created by HDS. Follow its step-by-step instructions carefully while it is essential getting HDS to work with SRM.

VMware vSphere & SRM with Hitachi Data Systems (HDS)

This post is about Site Recovery Manager (SRM) in combination with the storage system of Hitachi Data Systems (HDS). I’ve been working with over the last couple of months. This is a braindump of my knowledge about the product.

HDS has complete portfolio of storage solutions available. Every type of VMware environment can find a HDS solution suited for their needs. I’ve been working with the AMS2500. This is a SAS / SATA based storage array. It is a suitable solution for midrange size companies, but can also be used by enterprise size companies as a 2nd tier SAN. Next to this storage array HDS also provides enterprise class storage array with its Universal Storage Platform.

For both types of storage HDS provides best practices for VMware which can be found here for the AMS2000 series and here for the Universal Storage Platform VM.

Like all major storage vendors HDS also is a VMware partner when it comes to SRM. They committed themselves to the support of their storage systems with SRM through their HDS SRA 2.0.

For more information how to set up VMware SRM with HDS storage arrays take a look at the deployment guide here that HDS created. It’s a document that explains in detail how to setup your HDS storage array and HDS Storage Replicatoin Adapter (SRA) for the creation of your SRM environment.

For more information on HDS with VMware look at this resource page.