SIOS SANless clusters

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Storage Switzerland: Storage Q&A: High Availability for Data Centers of all Sizes

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SIOS Technologies and Storage Switzerland recently joined forces for a highly attended webinar. The attendees asked some outstanding questions about flexible HA and DR for virtual servers and cloud environments. Joining Storage Switzerland Founder and Chief Steward George Crump on the Webinar is Director of Field Engineering Tony Tomarchio from SIOS.

Question 1

“What are the connectivity requirements between two geographically dispersed data centers, such as bandwidth and latency, in order for your high availability solution to work?”

Tony: It all comes down to the workload that you need to protect. We don’t have a minimum requirement per se. It depends on the I/O activity on your system, specifically data rate of change, which is how rapidly your disks being written. Let’s say you have one server, which on average is writing 3MB/sec to disk. SIOS Software wants to replicate that data as fast as you write it to disk locally to replicate it out. You need to look at the servers you want to protect. In Windows this is very easy to do. You can pull up PerfMon, look at disk stats and let that run for some representative time period. That will tell you exactly how much bandwidth you need to support real-time replication.

As far as the latency aspect of this question goes, we support both synchronous and asynchronous replication. Generally, you would go with synchronous replication if you have a high-speed low latency network connection. Synchronous gives you maximum data protection and zero data loss because it’s a double commit. The write isn’t considered complete until it’s made it to both source and targets. But you do have to factor in the round trip latency between source/target as that will have an effect on your write performance.

If you have higher latency and you’re more performance sensitive, you might go with asynchronous. But you have to understand that in the event of a failure there could be some in flight data that might not make it from source to target. So there could be some data loss. That is the classic trade-off between synchronous and asynchronous.

To summarize, we don’t have a minimum requirement as far as bandwidth and latency. It really comes down to how busy your servers are, how rapidly they write to disk, what your performance tolerances are, and how much data loss, if any, you can withstand.

Question 2

“How are the SAN-less clusters beneficial in a VMware environment?”

Tony: If you deploy VMware, it’s got built-in features such as VMware HA. That is a partial solution from an HA perspective. If you look at what VMware HA does, it protects you against host failures. If a host fails, it reboots a virtual machine onto another physical host in the VMware cluster. If you have an issue with the networking or the application that’s inside the virtual machine, essentially the virtual machine is a block box and that type of issue won’t necessarily be protected. Adding on application level availability and clustering at the guest level can provide you with a higher level of availability.

The other challenge that I mentioned before with doing guest level clustering in that type of environment is that you have to pass the storage up to the virtual machine. Usually you’ll have to configure raw device mapping (RDM), and then you’ll lose things like VMotion. You’re giving up some virtualization features for HA, but with a SAN-Less cluster solution from SIOS you can have both. We’re doing everything from inside the guest. There are no specific changes you need to make at the hypervisor level.

Question 3

“What storage configuration provides the best HA?”

George: I’m a SAN guy. But clearly from a cost perspective, the ability to use external drives has to be appealing both from a cost and familiarity perspective. What is your stance on that?

Tony: Certainly SANs are robust and have a lot of redundancy, such as redundant controllers, disks and so on. But at the end of the day shared storage in your cluster represents a single point of failure. Again, it may not be a hardware failure. Many times it’s a configuration or user error that causes connectivity loss to the SAN that can take down your entire cluster.

By going to a SAN-less configuration, you’re eliminating storage as a single point of failure and achieving a higher level of availability.

If you already have made the investment in a SAN, I’m not saying don’t use it. You can certainly use existing storage and server resources that you have in your infrastructure. But if that’s the way you were clustering in the past, let’s say two servers and a SAN, you might consider adding a third node with it’s own independent storage. It could be a different SAN or it could be local storage. That way you’ve now got another node in the cluster so you can withstand one more host failure. You’re also eliminating storage as a failure point, so technically you’re stepping up one notch in the availability chain.

George: I wrote a paper on this and there was a section called, “What can go wrong with your SAN Array.”

One of the interesting things that can go wrong is most systems have a RAID or something going on to protect it in case of a drive failure. But one of the things I find that takes people off guard is what the performance is like while the RAID rebuild is happening. It typically leaves you with two choices. You can turn down the speed at which the rebuild is happening leaving you exposed for a longer period of time, or you can speed up the RAID rebuild which typically hurts the disk I/O performance.

It sounds to me that in your environment, I can fail to a separate stand alone system and let the RAID rebuild happen all by itself on a separate primary system. That would be able to work, wouldn’t it?

Tony: Yes, you could certainly do that if performance during that operation was a concern. Basically what happens at the physical level, like a RAID rebuild, is transparent to our software. That’s one of the reasons why you can mix and match servers.

One of the requirements with our Windows solution is that drive letters match and all of the volumes are the same size. Whether it’s a single disk or it’s a RAID 0, 1, 5 or 10, under the covers that are all transparent. So yes, if that was a concern, you could potentially failover to another node in the cluster and let everything run off of that while your RAID rebuilds on the other side.

Question 4

“Can you use your software for anything other than SQL?”

Tony: Yes, you can use it with any cluster-able service or application. Most commonly we’re protecting SQL. We have solutions for Linux where we do a lot of SAP, Oracle and NFS type clusters. It’s really all over the map.

We can also protect custom applications. That is one of the benefits of having a block level replication technology. It is server, storage and even application agnostic. You just tell us which partitions or volumes you want to replicate and whatever data happens to live in there and we’re going to protect. From that regard, this can be used for much more than just SQL.

Question 5

“How is application performance impacted by running the SAN-less software?”

Tony: This comes back to the mode of replication. We support both synchronous and asynchronous replication. With asynchronous replication, you’re not going to see any kind of performance impact. If synchronous, then you’re only going to see an impact on writes to disk because it’s a double commit. Reads are not impacted.

If you go with synchronous replication, you’ll want to have a low latency network connection to minimize the overhead that synchronous replication imposes on writes.

VI Briefing: SIOS SANLess Clustering Software Provides Epicure Selections with High Availability and Disaster Recovery Protection for Critical SQL Server Applications

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Epicure Selections deploys hybrid solution providing additional cost savings of running on-premises with the reliability and flexibility of running in the cloud

SAN MATEO, CA – January 20, 2015 – SIOS Technology Corp. (www.us.sios.com), maker of SAN and #SANLess clustering software products, today announced that Epicure Selections is using SIOS DataKeeper Cluster Edition software to easily and cost-efficiently provide HA and DR protection for its business-critical SQL Server applications without the complexity of building out a remote DR site or purchasing costly SQL Server Enterprise Edition licenses.

Epicure, Canada’s leading direct sales company, sells healthy, easy-to-prepare food products through a network of over 16,000 consultants.  Epicure relies on two websites for its critical business operations. Its public website provides product, company, and consultant enrollment information to customers and people interested in becoming a consultant. The internal website provides consultants with important product information and enables them to place orders.

The company uses two instances of SQL Server Standard Edition, one for each website running on a single server. “Our websites are vital to our business,” said Russell Born, senior network infrastructure administrator at Epicure.

As the company grew and expanded its products and services, the Epicure IT department needed to update and protect its business-critical websites from downtime. It decided to move both websites from a third-party hosted facility to its on-premises data center and Amazon Web Services. As part of this update, Epicure wanted an efficient, cost-effective way to provide high availability and disaster protection for both websites while continuing to run them on two instances of SQL Server Standard Edition.

Using SIOS SANLess clustering software, Epicure IT staff created a two-node cluster in an active-passive failover configuration that enables each SQL instance to failover independently. One cluster node is in the on-premises data center and the second node is in an instance of the AWS EC2 cloud. Epicure IT staff created the SIOS SANLess clusters and configured them using the software’s intuitive graphical user interface.

The SIOS software provides Epicure with an easy, cost-efficient way to provide HA and DR protection for its business-critical SQL Server applications without the complexity of building out a remote DR site or purchasing costly SQL Server Enterprise Edition licenses. “The SIOS software has allowed us to create a hybrid solution providing additional cost savings of running on-premises with the reliability and flexibility of running in the cloud,” said Born. “Knowing that a website outage will result in an automatic failover allows our IT Team to focus their attention on other priorities to strengthen our business.”

“Whether you want to protect applications in a physical server, a private cloud within an organization, in a public cloud or a hybrid cloud, you need to protect applications, like Windows SQL Server, from downtime if the cloud instance or the cloud provider fails,” said Jerry Melnick, COO, SIOS Technology.  “Epicure is using SIOS to provide a fast, easy way to deploy applications in a high availability environment in the cloud while continuing to use Windows Server Failover Clustering.  I applaud them for their use case and innovation and look forward to continuing to provide value to their HA and DR strategies.”

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.

Tech Target: SIOS SANLess cluster helps keep Epicure websites up and running

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Direct-sales food distributor Epicure deployed a new server cluster to keep its websites from being overwhelmed — and saved money on SQL Server and storage in the process.

Traffic on the two primary websites operated by Canadian direct-sales food distributor Epicure went up substantially at the end of each month — so much that the spikes often made the sites unusable. Epicure tried working with the third-party vendor that hosts the sites to resolve the problem, but saw no improvement. And the North Saanich, British Columbia company’s business model is dependent on the two sites. It uses one website to market itself and its selection of food and cookware products; the other site is used by the independent “consultants” who sell the Epicure products at tasting parties to place orders and communicate with the company.

Russell Born, senior network infrastructure administrator at Epicure, looked for a way to keep the sites running smoothly through the end-of-month rush — and, while doing a Google search last year, he found SIOS Technology Corp. and its DataKeeper data replication software andSANLess clustering tools. The SIOS offerings enable users looking to guard against processing downtime to create Windows or Linux server clusters that utilize local storage only, avoiding the need to deploy a storage area network (SAN).

“Before that, I thought we required a SAN,” Born said. SIOS also supports SAN-based clusters, but Epicure would have faced some difficulties if [it] went that route,” he added. According to Born, a SAN leads to higher costs and more setup effort; it also creates a “single point of failure,” since the entire operation becomes dependent on it to function. To combat that, Born could have deployed multiple SANs, but he said doing so would have become prohibitively expensive.

No backup in case of outage

Epicure had another good reason to want to bolster its websites, which use SQL Server to process and fulfill orders and track the work of its consultants. Shortly before Born learned about SIOS, Epicure’s data center suffered an outage that lasted several hours. “We didn’t have redundant Web servers, so there was no failover externally,” he said.The company had two servers, one for each site, and both were reaching their resource limit, which contributed to the end-of-month performance problems. In addition to SIOS, Born turned to cloud computing vendorAmazon Web Services (AWS) to help relieve the pressure. The new setup for Epicure includes a primary Web server running on-premises and a cloud-based failover system, and the SIOS software replicating data between them. Concurrently, Epicure is upgrading from SQL Server 2008 to SQL Server 2012, and from Windows 2008 to Windows 2012.Jerry Melnick, COO of San Mateo, Calif.-based SIOS, said one of the primary motivators for the deployment was Epicure’s concerns about disaster protection and recovery. “There is so much depending on those sites,” he said. “Users are ordering off the sites. If they go down, it could take weeks to get [them] back up.”One method for ensuring high availability is to deploy servers in a second location so that, if the primary data center goes down, you can failover to the backup one. But Melnick said that has a high startup cost, so he recommended companies like Epicure tap into a cloud provider, such asAWS, for disaster recovery. SIOS’ job, according to Melnick, is to be the linchpin of the SANLess cluster.

More money left on Epicure’s table

Consolidating the two servers into one primary system also saved the company some money on the DataKeeper software. “SIOS’ licenses are based on the number of servers, so it was half the cost,” Born said.

Also, prior to working with SIOS, Epicure had been using SQL Server Enterprise Edition solely because that was the only way to get the high-availability features included in the database. Now that Epicure is using the SIOS software, Born said it has been able to downgrade to the much less-expensive SQL Server Standard Edition, achieving “very substantial cost savings” on that as well.

Born started out with some reservations about the SIOS technology. “I did have concerns initially that if SIOS lost its data connection, there would be some corruption,” he said. “But we didn’t see that.” In fact, he was able to work out all of the startup issues with the SQL Server version of DataKeeper while testing the product, and only needed to make a couple calls to SIOS support. “It migrated over seamlessly,” Born said, adding that so far, he’s pleased with what the SIOS software has done for Epicure’s websites and the SQL Server systems that power them.Jessica Sirkin is associate site editor of SearchSQLServer. Email her at jsirkin@techtarget.com and follow us on Twitter: @SearchSQLServer.

Read more on TechTarget.com

Disaster Recovery Journal: Meeting the Protection Requirements of Business Critical Applications in Virtual Server, and Cloud Environments

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You can save money and gain tremendous IT agility, flexibility and efficiency in your data center by moving your applications to virtual server and cloud environments. However, there is significant confusion in enterprise IT management about how to meet the exacting availability requirements of business critical applications in these environments.

IT managers have a wide range of questions: Do you need high availability (HA) and disaster recovery (DR) protection in a public cloud? Are replication solutions sufficient? Can you provide high availability and disaster protection that doesn’t limit or offset the cost saving and flexibility benefits of virtualized environments? While HA and DR in a physical server environment is a straightforward matter of setting up a shared storage cluster, in virtual server and cloud environments, the best practices for HA and DR are not as clear.

Traditional HA and DR Protection

The traditional shared storage cluster is the preferred solution for achieving HA for business critical applications. When protecting applications based on SQL Server, IT staff often use Windows Server Failover Clustering (WSFC) to configure a cluster of two or more servers that share the same storage, usually via a SAN or NAS device. The application runs actively on one server and WSFC software monitors the server and application. If WSFC detects a failure, it orchestrates a recovery of all required application resources on another cluster node.

To achieve DR and protect applications from site failure today, IT typically uses a variety of replication or failover technologies and they require multiple products, scripts and manual steps to allow recovery at a remote site. Alternatively, more costly enterprise-grade SAN solutions are used to implement geo-clustering across geographically separate sites.

Challenges of Protecting Applications in Virtual Server and Cloud Environments

When moving to virtualization and cloud platforms, there are a number of application, database and hypervisor or cloud specific approaches to use for availability. Examples of database level solutions include SQL Server AlwaysOn Availability Groups (AOAG). In the cloud, regional isolation of workloads is an option typically provided as an add-on service to use for assembling an HA/DR configuration. However, there are limitations in these solutions that make achieving cost-effective and reliable availability challenging.

For instance, AOAG is a SQL database-only protection solution and does not replicate the entire storage volume, which may contain other application data. It uses log-shipping and can add significant CPU overhead slowing performance.

In cloud environments, most providers offer separate computing resources for local or site redundancy. Providers also offer data replication services between zones but do not include any application monitoring or failover capabilities. You’ll need to use other technologies to fashion a complete solution to achieve HA or DR.

In contrast to these approaches, traditional shared storage clustering is a comprehensive, full stack HA solution that protects the application across the OS and all lower operating software and hardware layers. The problem is that traditional clusters require shared storage limiting their usefulness in virtualization and cloud environments.

For instance, you can use shared storage clustering in the guest VM, but to do so you have to use Raw Device Mapping (RDM), which adds complexity and limits the flexibility. In cloud environments, shared storage isn’t even an option.

So, if shared storage clustering is the best solution for tier-1 application availability, is there a way to provide availability and disaster protection using clustering without shared storage?

SANLess Clustering for HA and DR Business Critical Applications

A simple way to gain the advantages of clustering in virtual server and cloud environments without the limitations of shared storage is to add SANLess clustering software to a Windows Server Failover cluster. This software allows you to create an HA cluster without the need for shared storage. It uses efficient, block level host-based replication to synchronize local storage on each cluster node so that it appears to WSFC as shared storage. It can be used in virtual server (any hypervisor), cloud, hybrid cloud, and in physical server environments using high performance (SSD) storage.

In some environments, you can configure SANLess clusters in the guest VM and use VMDK storage, eliminating the need for RDM. SANLess clusters give you both full high availability protection for your applications and data and flexibility. Using SANLess clusters allows you to use low cost local storage or high performance server-side flash to cluster. This gives you complete VM portability, live migration, and failover protection with very high performance.

To take advantage of the cost savings, flexibility and efficiency benefits of virtual server and the cloud you need a sound strategy for protecting important application environments from downtime and data loss. While the redundancy offered in cloud and some virtual server environments provides some level of protection, it is not sufficient for business critical applications. SANLess clusters provide an easy, cost-efficient way to protect applications in these environments where traditional shared storage clusters may not be practical or even possible.

About the Author:

Melnick-JerryJerry Melnick is the chief operating officer of SIOS Technology Corp. Melnick (jmelnick@us.sios.com) is responsible for defining corporate strategy and operations at SIOS Technology Corp. (www.us.sios.com), maker of SIOS SAN and #SANLess cluster software. He has more than 25 years of experience in the enterprise and high availability software industries. He holds a bachelor of science degree from Beloit College with graduate work in computer engineering and computer science at Boston University.

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Storage Newsletter — Mavis Discount Tire Keeps Servers Rolling

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SIOS Technology Corp., maker of SAN and SANLess clustering software products, announced that Mavis Discount Tire is using SIOS DataKeeper Cluster Edition software to ensure HA for its mission-critical SQL Server applications.

Mavis Discount Tire

Mavis Discount Tire is a New York-based tire retailer with 150 stores throughout the northeastern US. The company relies on business critical applications running on SQL Server 2008 R2 Enterprise Edition and SQL Server 2012 Enterprise Edition to manage their orders, inventory, and other business-critical processes. For retail stores, application performance is a critical priority.

“Our retail stores need fast, reliable access to these applications to operate,” said Edward Schwartz, CIO, Mavis Discount Tire. “To keep customer satisfaction high, we cannot afford slow response times or downtime.”

The company needed a way to provide HA protection for its SQL Server applications and databases that would not impede performance. The company considered using traditional clustering using Windows Server Failover Clustering (WSFC). However, to implement a traditional cluster solution and maintain the high level of performance they needed, Mavis Discount Tire would have required multiple SANs and both dedicated and redundant external switches.

“While a traditional WSFC environment would have protected our applications from downtime, it requires SAN storage which adds cost, complexity, and performance overhead,” said Schwartz.

Since the company does not store large volumes of data, they saw little value in the storage benefits of deploying external SANs. They were also concerned about the performance impact that SAN storage could have had on the highly transactional SQL Server databases.

The Mavis Discount Tire IT department chose SIOS SANLess software to provide HA and DR protection without the need for a SAN.

“We used WSFC to create two node clusters for our SQL environments in the same way a traditional cluster is created,” said Schwartz. “We simply added SIOS DataKeeper Cluster Edition software to enable the cluster to use local storage in a SANLess configuration.”

The SIOS software uses performance optimized host-based replication to synchronize local storage on the primary and standby nodes in the cluster so that it appears to the WSFC as a SAN. SIOS #SANLess cluster software provides HA without slowing performance. They also eliminated the single point of failure risk of a shared storage cluster.

“The SIOS DataKeeper Cluster Edition software is a good technology for a company that is growing rapidly. It is easy to use and eliminates the need to buy unnecessary SAN hardware or redundant switches,” said Schwartz.

“SIOS is providing opportunities for the creation of SAN and SANLess clusters for physical, virtual and cloud environments,” said Jerry Melnick, COO, SIOS Technology. “SIOS DataKeeper is a virtual SAN that runs under the application layer of SQL Server, allowing Mavis Tire to create SANLess clusters and benefit from all advantages of a second SAN without the performance challenges and added costs.”

Originally posted on StorageNewsletter.com on 12/19/2014.