The difference between VMware vSphere LCM (vLCM) and Dell EMC VxRail LCM is still a trending topic that most HCI customers and prospects want more information about. While we compared the two methods at a high level in our previous blog post, let’s dive into the more technical aspects of the LCM operations of VMware vLCM and VxRail LCM. The detailed explanation in this blog post should give you a more complete understanding of your role as an administrator for cluster lifecycle management with vLCM versus VxRail LCM.

Even though vLCM has introduced a vast improvement in automating cluster updates, lifecycle management is more than executing cluster updates. With vLCM, lifecycle management is still very much a customer-driven endeavor. By contrast, VxRail’s overarching goal for LCM is operational simplicity, by leveraging Continuously Validated States to drive cluster LCM for the customer. This is a large part of why VxRail has over 8,600 customers since it was launched in early 2016.

In this blog post, I’ll explain the four major areas of LCM:

• Defining the initial baseline configuration
• Planning for a cluster update
• Executing the cluster update
• Sustaining cluster integrity over the long term

Defining the initial baseline configuration

The baseline configuration is a vital part of establishing a steady state for the life of your cluster. The baseline configuration is the current known good state of your HCI stack. In this configuration, all the component software and firmware versions are compatible with one another. Interoperability testing has validated full stack integrity for application performance and availability while also meeting security standards in place. This is the ‘happy’ state for you and your cluster. Any changes to the configuration use this baseline to know what needs to be rectified to return to the ‘happy’ state.

How is it done with vLCM?

vLCM depends on the hardware vendor to provide a Hardware Management Services virtual machine. Dell provides this support for its Dell EMC PowerEdge servers, including vSAN ReadyNodes. I’ll use this implementation to explain the overall process. Dell EMC vSAN ReadyNodes use the OpenManage Integration for VMware vCenter (OMIVV) plugin to connect to and register with the vCenter Server.

Once the VM is deployed and registered, you need to create a credential-based profile. This profile captures two accounts: one for the out-of-band hardware interface, the iDRAC, and the other for the root credentials for the ESXi host. Future changes to the passwords require updating the profile accordingly.

With the VM connection and profile in place, a Catalog XML file is used by vLCM to define the initial baseline configuration. To create the Catalog XML file, you need to install and configure the Dell Repository Manager (DRM) to build the hardware profile. Once a profile is defined to your specification, it must then be exported and stored on an NFS or CIFS share. The profile is then used to populate the Repository Profile data in the OMIVVV UI. If you are unsure of your configuration, refer to the vSAN Hardware Compatibility List (HCL) for the specific supported firmware versions. Once the hardware profile is created, you can then associate it with the cluster profile. With the cluster profile defined, you can enable drift detection. Any future change to the Catalog XML file is done within the DRM.

It’s important to note that vLCM was introduced in vSphere 7.0. To use vLCM, you must first update or deploy your clusters to run vSphere 7.x.

How is it done with VxRail LCM?

With VxRail, when the cluster arrives at the customer data center, it’s already running in a ‘happy’ state. For VxRail, the ‘happy’ state is called Continuously Validated States. The term is pluralized because VxRail defines all the ‘happy’ states that your cluster will update to over time. This means that your cluster is always running in a ‘happy’ state without you needing to research, define, and test to arrive at Continuously Validated States throughout the life of your cluster. VxRail – well, specifically the VxRail engineering team - does it for you. This has been a central tenet of VxRail since the product first launched with vSphere 6.0. Since then it has helped customers transition to vSphere 6.5, 6.7, and now 7.0.

Once the VxRail cluster initialization is completed, use your Dell EMC Support credentials to configure the VxRail repository setting within vCenter. VxRail Manager plugin to vCenter will automatically connect to the VxRail repository at Dell EMC and pull down the next available update package.

Figure 1  Defining the initial baseline configuration

Planning for a cluster update

Updates are a constant in IT, and VMware is constantly adding new capabilities or product/security fixes that require updating to newer versions of software. Take for example the vSphere 7.0 Update 1 release that VMware and Dell Technologies just announced. Those eye-opening features are available to you when you update to that release. You can check out just how often VMware has historically updated vSphere here: https://kb.vmware.com/s/article/2143832.

As you know, planning for a cluster update is an iterative process with inherent risk associated with it. Failing to plan diligently can cause adverse effects on your cluster, ranging from network outages and node failure to data unavailability or data loss. That said, it’s important to mitigate the risk where you can.

How is it done with vLCM?

With vLCM, the responsibility of planning for a cluster update rests on the customers’ shoulders, including the risk. Understanding the Bill of Materials that makes up your server’s hardware profile is paramount to success. Once all the components are known, and a target version of vSphere ESXi is specified, the supported driver and firmware version needs to be investigated and documented. You must consult the VMware Compatibility Guide to find out which drivers/firmware are supported for each ESXi release.

It is important to note that although vLCM gives you the toolset to apply firmware and driver updates, it does not validate compatibility or support for each combination for you, except for the HBA Driver. This task is firmly in the customer’s domain. It is advisable to validate and test the combination in a separate test environment to ensure that no performance regression or issues are introduced into the production environment. Interoperability testing can be an extensive and expensive undertaking. Customers should create and define robust testing processes to ensure that full interoperability and compatibility is met for all components managed and upgraded by vLCM.

With Dell EMC vSAN Ready Nodes, customers can rest assured that the HCL certification and compatibility validation steps have been performed. However, the customer is still responsible for interoperability testing.

How is it done with VxRail LCM?

VxRail engineering has taken a unique approach to LCM. Rather than leaving the time-consuming LCM planning to already overburdened IT departments, they have drastically reduced the risk by investing over $60 million, more than 25,000 hours of testing for major releases, and more than 100 team members into a comprehensive regression test plan. This plan is completed prior to every VxRail code release. (This is in addition to the testing and validation performed by PowerEdge, on which VxRail nodes are built.)

Dell EMC VxRail engineering performs this testing within 30 days of any new VMware release (even quicker for express patches), so that customers can continually benefit from the latest VMware software innovations and confidently address security vulnerabilities. You may have heard this called “synchronous release”.

The outcome of this effort is a single update bundle that is used to update the entire HCI stack, including the operating system, the hardware’s drivers and firmware, and management components such as VxRail Manager and vCenter. This allows VxRail to define the declarative configuration we mentioned previously (“Continuously Validated States”), allowing us to move easily from one validated state to the next with each update.

Figure 2  Planning for a cluster update

Executing the cluster update

The biggest improvement with vLCM is its ability to orchestrate and automate a full stack HCI cluster update. This simplifies the update operation and brings enormous time savings. This process is showcased in a recent study performed by Principled Technologies with PowerEdge Servers with vSphere (not including vSAN).

How is it done with vLCM?

The first step is to import the ESXi ISO via the vLCM tab in the vCenter Server UI. Once uploaded, select the relevant cluster, ensure that the cluster profile (created in the initial baseline configuration phase) is associated with the cluster being updated. Now, you can apply the target configuration by editing the ESXi image and, from the OMIVV UI, choose the correct firmware and driver to apply to the hardware profile. Once a compliance scan is complete, you will have the option to remediate all hosts.

If there are multiple homogenous clusters you need to update, it can be as easy as using the same cluster profile to execute the cluster update against. However, if the next cluster has a different hardware configuration, then you would have to perform the above steps over again. Customers with varying hardware and software requirements for their clusters will have to repeat many of these steps, including the planning tasks, to ensure stack integrity.

How it is done with VxRail LCM?

With VxRail and Continuously Validated States, updating from one configuration to another is even simpler. You can access the VxRail Manager directly within the vCenter Server UI to initiate the update. The LCM operation automatically retrieves the update bundle from the VxRail repository, runs a full stack pre-update health check, and performs the cluster update.

With VxRail, performing multi-cluster updates is as simple as performing a single-cluster update. The same LCM cluster update workflow is followed. While different hardware configurations on separate clusters will add more labor for IT staff for vSAN Ready Nodes, this doesn’t apply to VxRail.  In fact, in the latest release of our SaaS multi-cluster management capability set, customers can now easily perform cluster updates at scale from our cloud-based management platform, MyVxRail.

Figure 3  Executing a cluster update

Sustaining cluster integrity over the long term

The long-term integrity of a cluster outlasts the software and hardware in it. As mentioned earlier, because new releases are made available frequently, software has a very short life span. While hardware has more staying power, it won’t outlast some of the applications running on them. New hardware platforms will emerge. New hardware devices will enter the market that will launch new workloads, such as machine learning, graphics rendering, and visualization workflows. You will need the cluster to evolve non-disruptively to deliver the application performance, availability, and diversity your end-users require.

How is it done with vLCM?

In its current form, vLCM will struggle in long-term cluster lifecycle management. In particular, its inability to support heterogeneous nodes (nodes with different hardware configurations) in the same cluster will limit its application diversification and its ability to take advantage of new hardware platforms without impacting end-users.

How it is done with VxRail LCM?

VxRail LCM touts its ability to allow customers to grow non-disruptively and to scale their clusters over time. That includes adding non-identical nodes into the clusters for new applications, adding new hardware devices for new applications or more capacity, or retiring old hardware from the cluster.

Conclusion 

Figure 4  Comparing vSphere LCM and VxRail LCM cluster update operations driven by the customer

The VMware vLCM approach empowers customers who are looking for more configuration flexibility and control. They have the option to select their own hardware components and firmware to build the cluster profile. With this freedom comes the responsibility to define the HCI stack and make investments in equipment and personnel to ensure stack integrity. vLCM supports this customer-driven approach with improvements in cluster update execution for faster outcomes.

Dell EMC VxRail LCM continues to take a more comprehensive approach to optimize operational efficiency from the point of the view of the customer. VxRail customers value its LCM capabilities because it reduces operational time and effort which can be diverted into other areas of need in IT. VxRail takes on the responsibility to drive stack integrity for the lifecycle management of the cluster with Continuously Validated States. And VxRail sustains stack integrity throughout the life of the cluster, allowing you to simply and predictably evolve with technology trends.

Cliff Cahill
VxRail Engineering Technologist
Twitter @cliffcahill
LinkedIn http://linkedin.com/in/cliffcahill

Enabling high performance for HCI workloads is exactly what happens when VxRail is configured with Intel Optane Persistent Memory (PMem). Optane PMem provides compute and storage performance to better serve applications and business-critical workloads. So, what is Intel Optane Persistent Memory? Persistent memory is memory that can be used as storage, providing RAM-like performance, very low latency and high bandwidth. It’s great for applications that require or consume large amounts of memory like SAP HANA, and has many other use cases as shown in Figure 1 and VxRail is certified for SAP HANA as well as Intel Optane PMem.  

Moreover, PMem can be used as block storage where data can be written persistently, a great example is for DBMS log files. A key advantage to using this technology is that you can start small with a single PMem card (or module), then scale and grow as needed with the ability to add up to 12 cards. Customers can take advantage of PMem immediately because there’s no need to make major hardware or configuration changes, nor budget for a large capital expenditure. 

There are a wide variety of use cases today including those you see here:

Figure 1: Intel Optane PMem Use Cases

PMem offers two very different operating modes, that being Memory and App Direct, and in turn App Direct can be used in two very different ways.

First, Intel Optane PMem in Memory mode is not yet supported by VxRail.  This mode acts as volatile system memory and provides significantly lower cost per GB then traditional DRAM DIMMs. A follow-on update to this blog will describe this mode and test results in much more detail once it is supported.

As for App Direct mode (supported today), PMem is consumed by virtual machines as either a block storage device, known as vPMemDisk, or as byte addressable memory, known as Virtual NVDIMM. Both provide great benefit to the applications running in a virtual machine, just in very different ways. vPMemDisk can be used by any virtual machine hardware, and by any Guest OS.  Since it’s presented as a block device it will be treated like any other virtual disk. Applications and/or data can then be placed on this virtual disk. The second consumption method, NVDIMM has the advantage of being addressed in the same way as regular RAM, however, it can retain its data through reboots or power failures. This is a considerable plus for large in-memory databases like SAP HANA where cache warm-up or the time to load tables in memory  can be significant!

However, it’s important to note that, like any other memory module, the PMem module does not provide data redundancy. This may not be an issue for some data files on commonly used applications that can be re-created in case of a host failure. But a key principle when using PMem, either as block storage or byte addressable memory is that the applications are responsible for handling data replication to provide durability. 

New data redundancy options are expected on applications that are using PMem and should be well understood before deployment.

First, we’ll look at test results using PMem as virtual disk (or vPMemDisk). Our Engineering team tested VxRail with PMem in App Direct mode and ran comparison tests against a VxRail all-flash (P570F series platform). The testing simulated a typical 4K OLTP workload with 70/30 RW ratio. Our results achieve more than 1.8M IOPs or 6X more than the all-flash VxRail system. That equates to 93% faster response times (or lower latency) and 6X greater throughput as shown here:

Figure 2: VxRail PMem App Direct versus VxRail all-flash

This latency difference indicates the potential to improve the performance of legacy applications by placing specific data files on a PMem module, for example, placing log files on PMem. To verify the benefit of this log acceleration use case we ran a TPC-C benchmark comparing VxRail configured with a log file on a vPMEMDIsk to a VxRail all-flash vSAN, and we saw a 46% improvement on the number of transactions per minute.

Figure 3: Log file acceleration use case

For the second consumption method, we tested PMem in App direct mode using the NVDIMM consumption method. We performed tests using 1,2,4,8 and then 12 PMEM modules. All testing has been evaluated and validated by ESG (Enterprise Strategy Group). The certified white paper has been published as highlighted in the resources section.

Figure 4: NVDIMM device testing (vSAN not-optimized versus optimized PMem NVDIMM)

The results prove linear scalability as we increase the number of modules from 1 to 12. And with 12 PMem modules, VxRail achieves 80 times more IOPs than when running against vSAN not optimized (meaning VxRail all-flash vSAN with no PMem involved), and 100X for the 4K RW workload. The right half of the graphic depicts throughput results for very large IO, 64KB. When PMem is optimized on 12 modules we saw 28X higher throughput for a 64KB random read (RR) workload, and PMem is 13 times faster for the 64K RW.

What you see here is amazing performance on a single VxRail host and almost linear scalability when adding PMem!! Yes, that warrants a double bang. If you were to max out a 64-node cluster, the potential scalability is phenomenal and game changing! 

So, what does all this mean? Key takeaways are:  

• The local performance of VxRail with Intel Optane PMem can scale to 12M read IOPS, and more than 4M write IOPs or 70GB/s read throughput / 22GB/s write throughput on a single host.
• The use of PMEM modules doesn’t affect the regular activity on vSAN Datastores and extends the value of your VxRail platform in many ways;
  • It can be used to accelerate legacy applications, such as RDBMS Log acceleration
  • It enables the deployment of in memory databases and applications that can benefit from the higher IO throughput provided by PMEM while still taking the benefit of vSAN characteristics in the VxRail platform 
  • The local performance of a single host with 12 x 128GB PMem modules achieves more than 12M read IOPS, and more than 4M write IOPs
  • It not only increases performance of traditional HCI workloads such as VDI, but also support performance-intensive transactional and analytics workloads
  • It offers orders-of-magnitude faster performance than traditional storage
  • It provides more memory for less cost as PMem is much less costly than DRAM

The references and validation testing have been completed by ESG (Enterprise Strategy Group).  White papers and other resources on VxRail for Extreme Performance are available via the links listed below.

Additional Resources

ESG Validation: Dell EMC VxRail and Intel Optane Persistent Memory

VxRail and Intel Optane for Extreme Performance – Engineering presentation

High Performance for HCI Workloads with Dell EMC VxRail & Intel Optane Persistent Memory - infographic

Dell EMC & Intel Optane Persistent Memory - video

ESG Validation: Dell EMC VxRail with Intel Xeon Scalable Processors and Intel Optane SSDs

By: KJ Bedard – VxRail Technical Marketing Engineer

LinkedIn: https://www.linkedin.com/in/kj-bedard-50b25315/

Twitter: @KJbedard