S T O R A G E Ensuring Data Availability for the Enterprise with Storage Replica A Q&A with Microsoft s Senior Program Manager, Ned Pyle Data is the lifeblood of any company, which is a key reason why Microsoft is adding significant new capabilities to Windows Server designed to ensure data availability in a flexible, secure and relatively inexpensive way. Storage Replica provides block-level, synchronous replication between servers or clusters for disaster preparedness, recovery and high availability (Figure 1). First demonstrated at TechEd in Barcelona, Storage Replica is available for testing now in Windows Server 2016 Technical Preview. Indeed, the fact that Storage Replica is integrated into Windows Server is a big part of what makes the feature such an important advancement for the enterprise.
Figure 1. Shown here are supported replication scenarios using Storage Replica. Ned Pyle, Microsoft senior program manager, provided insight into the new feature and the impact it will have on the enterprise. What is Storage Replica, and why is it important right now? It s a brand-new feature in Windows Server 2016. It is block-level replication it doesn t operate on files, it operates on the blocks under volumes the data inside the lower-level storage. It really serves only one purpose, which is to help customers survive a disaster that wipes out a server, servers, or a data center, by providing a copy of that data that resides somewhere else. And all of this happens synchronously, meaning that every time you write data in one data center you write it in the other data center, at the exact same moment. With the integration of Storage Replica, what will Windows Server admins and storage managers find different? Well, for one thing, this kind of capability has never existed in Windows before, so the biggest change is they will have a way to do this kind of replication at all. It s a kind of technology that has existed in the storage industry for about 20 years, and to use it you paid a lot of money, and you typically could only use it from a proprietor of a particular type of storage. So, somebody sells you a storage array, and they ll sell you STORAGE 2
the associated software that they also own and make you re not allowed to use anything else, and you often end up paying through the nose. As a customer, it s very unlikely that you ve actually seen block-level replication because you probably couldn t afford it. Storage Replica really is what I d like to call the great democratizer: It comes in Windows, Server so it costs what Windows Server costs. For people in the Windows Server world, unless you were a Fortune 1000 business, maybe, the idea that you would have block-level replication in your environment was pretty unlikely because of the cost. This really opens up an entirely new world where somebody who has bought a couple of copies of Windows Server Datacenter now can do something that used to cost hundreds of thousands or even millions of dollars for just a few thousand. Is there a reason why this kind of functionality hasn t made its way into Windows Server before now? Only a few years ago did Microsoft start getting serious about storage. In 2012, we started taking on the storage industry and inventing a whole new class of Windows Server called Scale-Out File Servers and SMB [Server Message Block] 3 and a bunch of other stuff. At the same time, we were working on Storage Replica. This is a natural progression toward a stack that, end to end, is competitive with the more expensive Fiber Channel attached storage arrays. We ve made other replication products in the past, but Microsoft has typically worked in the world of files and not blocks. We made application replication, like SQL AlwaysOn Availability Groups and Hyper-V Replica. Those are products that replicate one thing themselves. Storage Replica is our first real attempt at doing something that is a true storageagnostic system. It s host-based, so you don t even have to use Windows storage, so to speak. You can use a SAN (storage-area network), an iscsi target, JBODs (Just a Bunch of Disks) in a SAS enclosure, or DAS (Direct Attached Storage). The actual thing being replicated doesn t have to be Windows--the Windows Server will do the work, but the actual storage can be anything that looks like a drive to Windows. So you can kind of put your toe in the water on this and say, I don t want to get rid of my SAN, but I ll use Windows to replicate and I ll stop paying top dollar for STORAGE 3
proprietary replication from the SAN maker or some third party from which I bought an expensive add-on for replication. What are some of the other benefits to Storage Replica? The initial benefit that people usually think of and see is, oh, I can finally just take a couple of important servers and make sure their data is replicated somewhere else so that if I have a disaster I don t have to go to some backups and lose all my work from that whole day or week, or from whenever the last time we backed things up. That s a pretty obvious one the simple one to one. We also have built cluster integration into Storage Replica, so you can take a normal Windows failover cluster and turn it into what we call a stretched cluster. You can take your normal failover cluster that you have been using for years things like Hyper-V or SQL or whatever--and stretch it across two sites. In the past, use of this type of feature was very rare because you had to buy extra software to do this software not made by Microsoft. Now you can just take half of a cluster and put it in one site and the other half at another site, and it will operate exactly like a normal cluster except that Storage Replica keeps the nodes synchronized across the sites the whole time. You don t need to retrain your staff on using a cluster because it still works normally it does automatic failover, it runs all the normal roles except, now, you could lose half the normal cluster to a data center being destroyed and, effectively, nothing happens. You come online almost instantly, and you lose zero data. We also do cluster to cluster. We ll see how interesting that will be to people, because it will be fairly expensive to do owning two clusters in the first place, then replicating them. Would certain types of organizations be better-suited to this type of feature than others? The feature would be most appealing to somebody who is not just creating a small disaster recovery site, but who actually operates multiple, full-power data centers. And what you would tend to do there is you d take two clusters and replicate the contents of them in both directions so that each one was doing work all day long and the other one was essentially copying that work. Let s say you were a big automotive company. You probably have five or six data STORAGE 4
centers around the country or around the world. You could replicate between those, and then, if you lose a data center, all your work fails over. That one cluster that s left is probably a lot busier than it used to be, but it still operates. So many companies today are spread out, physically. How far can companies replicate using storage replication? The first question people ask is, How far can I replicate? In the case of synchronous replication, our recommendation is around latency, not distance. We say, as long as your round trip is 5 ms or less, then that works. That range will be different depending on the customer, however. With some customers that may only be a mile. With others, it might be 100 miles. Storage Replica also uses SMB 3, which has a lot of really great capabilities built into it for being a transport for other technologies. We are one of those new technologies realizing a lot of earlier investments in SMB. We get encryption for free, signing for free, multichannel, RDMA all of that stuff comes to us for free inside of Storage Replica. We don t have to do any work; we can kind of re-leverage the stuff we ve already done, so we re incredibly fast and low-latency. We can use RDMA networks, for example, just like SMB can, and get you much faster connectivity and lower latency, lower CPU overhead, all while doing the replication. So we re kind of closing the loop on Windows storage for the first time in 20 years. Do you think Storage Replica will play a big role in driving customers to upgrade to Windows Server 2016 more quickly or at all? I sure hope so. This Windows Server release is a pretty major one. 2012 R2 was a fairly minor release from the storage perspective; 2012 was major. This one probably has at least as many new features, scenarios and abilities as in the big 2012 release. Customers have been running Storage Replica since October, and we ve been working on it for two years. It s not something that we just banged out since 2012 R2. We spent a lot of effort on this, and we feel from talking to customers, through interviews and from feedback from conferences, that Storage Replica will be something that drives a lot of people to want to run Windows Server 2016. During the last couple years, there have been a lot of big changes at Microsoft, especially in terms of the company s attitude toward openness. STORAGE 5
Do you think Server Replica is a result of those changes? Or at least reflective of the changes? We didn t make block replication for a long time, and when customers told us, You need to make block replication to be a serious part of the storage stack, we immediately made it. I ve been at Microsoft for 10 years, and in the last couple of years I think we ve probably been listening to customers more than we ever have in the last 20. It s quite astonishing how much. I m really glad to see the shields come down, and us listening more than talking. The Right Replication Mode for the Right Job Microsoft Storage Replica supports both synchronous and asynchronous replication. The Storage Replica Overview (https://technet.microsoft.com/en-us/library/ mt126183.aspx) on Microsoft TechNet describes the replication modes and their applications, as follows: Synchronous Replication Synchronous replication guarantees that the application writes data to two locations at once before completion of the IO (Figure 2). This replication is more suitable for mission-critical data, as it requires network and storage investments, as well as a risk of degraded application performance. Synchronous replication is suitable for both high-availability and disaster recovery solutions. Figure 2. Storage Replica supports synchronous replication. STORAGE 6
Asynchronous Replication Asynchronous replication means that when the application writes data, the data replicates to the remote site without immediate acknowledgment guarantees (Figure 3). This mode allows faster response time to the application, as well as a disaster-recovery solution that works geographically. Figure 3. Storage Replica also supports asynchronous replication, as shown here. Storage Replica is available for testing now, as part of the Windows Server 2016 Technical Preview 2 (https://www.microsoft.com/en-us/evalcenter/ evaluate-windows-server-technical-preview?wt.mc_id=blog_ws_announce_ TTD). STORAGE 7