Running VMware vsan Witness Appliance in VMware vcloudair First Published On: April 26, 2017 Last Updated On: April 26, 2017

Transcription

1 Running VMware vsan Witness Appliance in VMware vcloudair First Published On: April 26, 2017 Last Updated On: April 26,

2 Table of Contents 1. Executive Summary 1.1.Business Case 1.2.Solution Overview 1.3.Key Results 2. Running vsan Witness Appliance in vcloudair Reference Architecture 2.1.Purpose 2.2.Scope 2.3.Audience 3. Technology Overview 3.1.Overview 3.2.VMware vsphere 6.0 Update VMware vsan VMware vcloud Air 4. Solution Configuration 4.1.Overview 4.2.Architecture Configuration 4.3.Hardware Resources 4.4.Infrastructure VM Configuration 4.5.vSAN Disk Group and Fault Domain Configuration 4.6.Witness Appliance Deployment in vcloud Air 4.7.Network Configuration 4.8.VMware ESXi Server: Storage Controller Mode 4.9.Storage Policy Settings 4.10.HCIBench Profile 4.11.Advanced Settings of vsan 5. Solution Validation 5.1.Overview 5.2.Performance Data Collection Tools 5.3.Performance Comparison between Witness in vcloud 5.4.Performance Comparison between Witness in vcloud 6. Conclusion 6.1.Conclusion 7. Reference 7.1.White Paper 7.2.Product Documentation 7.3.Other Documentation 8. About the Author and Contributors 8.1.About the Author and Contributors 2

3 1. Executive Summary This section covers the Business Case, Solution Overview and Key Results of the 'Running VMware vsan Witness Appliance in VMware vcloudair' document. 3

4 1.1 Business Case After introducing the capabilities of fault domains and virtual witness appliances in VMware vsan 6.1, VMware has received numerous requests asking how to place the virtual witness appliance in VMware vcloud Air. This document is intended to provide a reference architecture for placement of the vsan witness appliance in vcloud Air, supporting both Stretched Cluster and 2-Node configurations. Both vsan Stretched Cluster deployment and 2-Node vsan deployment require a witness appliance running in a third location to provide quorum. The purpose of vsan witness appliance is to provide judgement if a split-brain situation occur. The witness appliance can be placed either in a customerowned on-premises data center or in public clouds such as vcloud Air or the vcloud Air Network. Placing a witness appliance in vcloud Air can bring customers all the benefits of public cloud for witness components. Customers do not need a dedicated site, or even dedicated hardware to host witness appliances, reducing both the costs and management effort of physical servers for a witness appliance. Furthermore, as business requirements and workloads grow, witness appliances in vcloud Air can be easy to scale up and scale out. This reference architecture demonstrates that running the witness appliance for vsan Stretched Cluster and 2-Node vsan ROBO Cluster in vcloud Air is fully supported. The performance testing results show that running the witness appliance in vcloud Air has no impact on performance comparing to running the witness appliance in an on-premises data center. In addition, various failure testing results show that the architecture with witness appliance in vcloud Air carries no additional risk of data loss and has only slight performance impact. 1.2 Solution Overview This solution covers the witness appliance deployment method in vcloud Air, network configuration between vcloud Air and on-premises data center, and vsan configuration. This solution covers both vsan Stretched Cluster and 2-Node vsan ROBO Cluster. In both architectures, a witness appliance is needed to run in a third site to provide quorum. This solution compares the performance between running the witness appliance in an on-premises data center and running it in vcloud Air. The results show that running the witness appliance in vcloud Air has no impact on performance. This solution also includes various failure scenario testing, and results show that running the witness appliance in vcloud Air is robust and the performance is only slightly affected with failure occurrences. Note: vsan ROBO deployment is a license instead of an architecture. The node number limit for vsan ROBO deployment is 64, which is the same number for vcluster. We use the term 2-Node vsan ROBO in this reference architecture to indicate that we run the tests with the minimal configuration requirement. In addition to the CPU-socket-based license, VMware also provides a vsan ROBO deployment license with 25 virtual machines. Users can apply this license to multiple ROBO sites and each ROBO site can have 2 to 64 physical hosts. 1.3 Key Results This reference demonstrates: Running a vsan witness appliance in vcloud Air for vsan Stretched Cluster is fully supported. Running a vsan witness appliance in vcloud Air for 2-Node vsan ROBO Cluster is fully supported. Running a vsan witness appliance in vcloud Air has no performance impact comparing to running witness appliance in local on-premises data center. 4

5 Running a vsan witness appliance in vcloud Air can tolerate various failures and the performance is only slightly affected during failure. 5

6 2. Running vsan Witness Appliance in vcloudair Reference Architecture This section provides the purpose, scope and the intended audience for this reference architecture 6

7 2.1 Purpose This reference architecture validates the ability to run the vsan witness appliance in vcloud Air for both vsan Stretched Cluster and 2-Node vsan ROBO Cluster. This reference architecture shows the procedure of deploying and managing a vsan witness appliance in vcloud Air. It proves that the performance is not affected when running the witness appliance in vcloud Air. The test results validate that this architecture can handle hardware failures in a production environment. Data integrity is maintained while performance is minimally affected. Failure tests demonstrate that running the vsan witness appliance in vcloud Air is a robust solution. 2.2 Scope This reference architecture: Demonstrates deploying and managing vsan witness appliance in vcloud Air. Shows the network configuration between vcloud Air and on-premises data center. Shows the baseline performance of 2-Node vsan ROBO Cluster and Stretched Cluster with witness appliance in local on-premises data center. Illustrates the comparative performance of 2-Node vsan ROBO Cluster with witness appliance in vcloud Air. Illustrates the comparative performance of vsan Stretched Cluster with witness appliance in vcloud Air. Demonstrates the resiliency of 2-Node vsan ROBO Cluster and Stretched Cluster with witness appliance in vcloud Air. 2.3 Audience This reference architecture is intended for information technology architects and storage architects involved in planning, architecting, and administering an environment with 2-Node vsan deployment or vsan Stretched Cluster deployment. 7

8 3. Technology Overview This section provides an overview of the technologies used in this solution. 8

9 3.1 Overview This section provides an overview of the technologies used in this solution: VMware vsphere 6.0 Update 2 VMware vsan 6.2 VMware vcloud Air 3.2 VMware vsphere 6.0 Update 2 VMware vsphere is the industry-leading virtualization platform for building cloud infrastructures. It enables users to run business-critical applications with confidence and respond quickly to business needs. vsphere accelerates the shift to cloud computing for existing data centers and underpins compatible public cloud offerings, forming the foundation for the industry s best hybrid cloud model. 3.3 VMware vsan 6.2 VMware vsan is VMware s software-defined storage solution for hyper-converged infrastructure, a software-driven architecture that delivers tightly integrated computing, networking, and shared storage from x86 servers. vsan delivers high performance and highly resilient shared storage by clustering server-attached flash devices and hard disks (HDDs). vsan delivers enterprise-class storage services for virtualized production environments along with predictable scalability and all-flash performance, all at a fraction of the price of traditional, purposebuilt storage arrays. Just like vsphere, vsan provides users the flexibility and control to choose from a wide range of hardware options and easily deploy and manage it for a variety of IT workloads and use cases. 9

10 Figure 1. vsan Cluster Datastore vsan can be configured as either a hybrid or an all-flash platform. In a hybrid disk architecture, vsan leverages flash-based devices for performance and magnetic disks for capacity. In an all-flash disk architecture, vsan uses flash-based devices (PCIe SSD or SAS/SATA SSD) for both caching and persistent storage. It is a distributed object storage system that uses the vsphere Storage Policy Based Management (SPBM) framework to deliver centrally managed, application-centric storage services and capabilities. Administrators can specify storage attributes, such as capacity, performance, and availability, as a policy on a per-vmdk level. The policies dynamically self-tune and load balance the system so that each virtual machine has the right level of resources. 3.4 VMware vcloud Air vcloud Air is a secure public cloud platform, built on the trusted foundation of vsphere. Workload portability, seamless networking, and common management make it easy to extend to the cloud from on-premises environments. vcloud Air is uniquely positioned to solve three critical IT challenges whether your customers need an affordable disaster recovery option, an efficient way to extend their data center, or a complete data center replacement. Figure 2 illustrates the vcloud Air features. 10

11 Figure 2. vcloud Air Features 11

12 4. Solution Configuration This section introduces the resources and configurations for the solution including architecture configuration, hardware & software resources and other relevant VM and storage configurations. 12

13 4.1 Overview This section introduces the resources and configurations for the solution including: Architecture configuration Hardware resources Infrastructure VM configuration vsan disk group and fault domain configuration Witness appliance deployment in vcloud Air Network configuration VMware ESXi Server: Storage Controller Mode Storage policy settings HCIBench profile Advanced settings 4.2 Architecture Configuration The tests cover two different scenarios: 2-Node vsan ROBO Cluster, and vsan Stretched Cluster. Each scenario requires a witness appliance in the cluster configuration. To compare the witness performance, we[1] conduct two sets of experiments using the following steps: 1. Place the witness in a local on-premises data center. 2. Place the witness appliance in vcloud Air. 3. Compare the performance between the two types of configurations. In the following architecture diagrams, we use a local on-premises data center to hold the infrastructure virtual machines. These architectures reflect the actual testbeds for the experiments. However, the local on-premises data center is not necessarily required. Users can also place all the infrastructure virtual machines in vcloud Air. Based on the architectures with a local on-premises data center, we assume the networking between the local on-premises data center and a ROBO site or Stretched Cluster sites already exists. This is a typical networking connectivity requirement for a corporate network. In the diagrams, the Routed Network indicates the existing routed network in a corporate network topology. Only one VPN between vcloud Air and the local on-premises data center is required in the following configurations. On the other hand, if users choose to get rid of the local on-premises data center and place all infrastructure virtual machines in vcloud Air, VPNs from vcloud Air to each site and network connectivity between sites are required. Under this circumstance, the VPN setup method is not changed and users just need to repeat the configurations for each site. The VPN setup method is introduced in the VPN Configuration section. Figure 3 shows the architecture of a 2-Node vsan ROBO Cluster with the witness appliance in the local on-premises data center. 13

14 Figure 3 2-Node vsan ROBO Cluster with Witness Appliance in Local On-premises Data Center Figure 4 shows the architecture of a 2-Node vsan ROBO Cluster with the witness appliance in vcloud Air. 14

15 Figure 4. 2-Node vsan ROBO Cluster with Witness Appliance in vcloud Air Figure 5 shows the architecture of a vsan Stretched Cluster with the witness appliance in the local onpremises data center. 15

16 Figure 5. vsan Stretched Cluster with Witness Appliance in Local On-premises Data Center Note: vsan Stretched Cluster supports both layer-2 network and routed layer-3 networking between site B and site C. Figure 5 shows the use of a routed layer-3 network in our environment. Figure 6 shows the architecture of a vsan Stretched Cluster with the witness appliance in vcloud Air. 16

17 Figure 6. vsan Stretched Cluster with Witness Appliance in vcloud Air 4.3 Hardware Resources Table 1 shows the configuration of each vsan ESXi Server in both 2-Node vsan ROBO Cluster and vsan Stretched Cluster configurations. Table 1. Server Configuration PROPERTY ESXi Server model SPECIFICATION 2 x x86 Servers 17

18 PROPERTY ESXi host CPU ESXi host RAM SPECIFICATION 2 x 20 CPU 3.0GHz v2 512GB ESXi version ESXi 6.0 build Network adapter 2 x 10Gbps SFI/SFP+ Storage adapter SMC 3008 Disks Cache SSD: 2 x 800GB (6Gbps) Capacity HDD: 12 x 1.2TB (6Gbps) 4.4 Infrastructure VM Configuration Single vcenter Server with following roles: vcenter vcenter single sign-on (SSO) vcenter Inventory Service HCIBench controller virtual machine Table 2 shows the infrastructure VM configuration. INFRASTRUCTURE VM ROLE vcpu RAM (GB) STORAGE (GB) OS vcenter appliance, build SUSE Linux Enterprise 11 vsan witness appliance VMware ESXi 6 HCIBench controller VMware Photon 4.5 vsan Disk Group and Fault Domain Configuration The 2-Node vsan ROBO Cluster and vsan Stretched Cluster configurations in our tests differ in network configuration but have the same disk group configuration. Each server is deployed with an identical configuration and the ESXi Server is booted from local disk. The fault domain setting uses the default value: each ESXi host is one vsan fault domain. Table 3 shows the disk group configuration on the ESXi hosts. Each host has two disk groups including 2 SSDs and 12 HDDs. Table 3. Disk Group Configuration 18

19 CONFIGURATION NUMBER CAPACITY (GB) Disk groups per host 2 For each disk group: - 1 SSD as the cache tier - 6 HDDs as the capacity tier HDD as the capacity tier per disk group 6 1,200 GB SSD as the cache tier per disk group GB 4.6 Witness Appliance Deployment in vcloud Air Perform the following steps to deploy a vsan witness appliance in vcloud Air: 1. Download the vsan witness appliance from MyVMware account. 2. Use vcloud Director to manage the vcloud Air instance. Go to Catalogs->vApp Templates, click the Upload button. Then choose the downloaded witness ova package, name it and click Upload as shown in Figure 7. 19

20 Figure 7. Upload vsan Witness Appliance ova to vcloud Air 3. Wait for the uploading process to complete as shown in Figure 8 Figure 8. Make Sure the Uploading is Successful 4. Click Add vapp from Catalog on the vcloud Director home page as shown in Figure 9. Figure 9. Add vapp from Catalog on vcloud Director Home Page 5. Find the witness appliance template in the All Templates list. Choose it and click Next as shown in Figure

21 Figure 10. Choose the Newly Uploaded vsan Witness Appliance Template to Deploy 6. On the Network Mapping page, make sure that Management Network and Witness Network use the proper networks. We use VLAN1721 and VLAN1722 in our example as shown in Figure 11. These VLANs will also be used in the VPN configuration in the next section. 21

22 Figure 11. Choose the Proper Networks The witness appliance is properly deployed and is ready for use. 4.7 Network Configuration VPN Configuration For a good communication between witness appliance in vcloud Air with vcenter Server and ESXi hosts in local on-premises data center, a VPN tunnel between vcloud Air and local on-premises data center must be properly configured. For details about setting up a site-to-site IPSec VPN within vcloud Air to a remote network, see VMware Knowledge Base In our tests, the site-to-site IPSec VPN is set up as shown in Figure

23 Figure 12. Site-to-site IPSec VPN Configuration between vcloud Air and Local On-premises Data Center vcloud Air supports enabling IPSec VPN in vcloud Air Edge Gateway Services directly. Managing vcloud Air instance in vcloud Director mode and choose Virtual Data Center->Administration->Edge Gateways, then right click on the Edge Gateway and choose Edge Gateway Services as shown in Figure 13. Figure 13. vcloud Air IPSec VPN Configuration Page On the VPN tab, check the Enable VPN box and then click Add. 23

24 Figure 14. vcloud Air IPSec VPN Configuration Dialog In the details page, fulfill the network configuration details based on the customized networks. For example, based on our network configuration as shown in Figure 12, the detailed configuration page should be fulfilled as shown in Figure

25 25

26 Figure 15. vcloud Air IPSec VPN Configuration Details Page In the detailed configuration page, the Local Networks refers to networks in vcloud Air. The Peer Networks refers to networks in the on-premises data center. Local ID is the public IP address of the vcloud Air instance. Peer ID or Peer IP is the public IP address of the on-premises data center s gateway (VPN endpoint). For explanation of each field, refer to VMware Knowledge Base After the VPN service in vcloud Air Edge Services is properly configured, vcloud Air provides a very convenient way to show the peer VPN endpoint configuration. Go back to Figure 14, the Peer Settings button is enabled at this step. Click this button and the peer configurations are displayed as shown in Figure

27 Figure 16. vcloud Air IPSec VPN Peer Settings This page helps administrators configure the IPSec VPN endpoint in the on-premises data center. Administrators configure their own VPN endpoint exactly as this page displays, then the VPN tunnel should be successfully set up. Because the configuration of on-premises data center VPN endpoint is differentiated by different network devices, we will not include this part. Administrators should refer to the device configuration guide, such as a router configuration guide. VPN Validation After VPN is properly configured, we use the Ping commands to test connectivity from vcloud Air to on-premises data center and from on-premises data center to vcloud Air bi-directionally. If the ping 27

28 test is successful, we can further add the witness appliance in vcloud Air to the local vcenter to prove that network is fully functional as shown in Figure 17. Figure 17. Add Witness Appliance in vcloud Air to Local vcenter After the witness is successfully added to the local vcenter, we can configure the 2-Node vsan ROBO Cluster or vsan Stretched Cluster respectively per the VMware vsan 6.2 Stretched Cluster and 2- Node Guide. Network Emulation When placing the witness appliance in an on-premises data center, we use a software router to emulate network delay and bandwidth limit in both 2-Node vsan ROBO Cluster and vsan Stretched Cluster tests. See the related blog for details about how to set up the bandwidth limit and latency. For the 2-Node vsan ROBO Cluster, we set the bandwidth between the witness and a simulated remote-office site to 500ms RTT latency and 1.5 Mb/s. This is the minimum requirement for a 2-Node configuration. For vsan Stretched Cluster, based on the VMware vsan 6.2 Stretched Cluster and 2-Node Guide, the rule is 2 Mb/s for every 1,000 vsan components. We therefore set the bandwidth between the witness and Stretched Cluster sites to 200ms RTT latency and 2 Mb/s, which is also the minimum requirement for a Stretched Cluster configuration. 28

29 The network emulation is used to configure the vsan ROBO Cluster with a witness appliance residing in an on-premises data center. This is used for comparing performance with the witness appliance residing in vcloud Air. Network to vcloud Air Measurement We test the real network latency and bandwidth from the on-premises data center to vcloud Air. We use the ping command to test network latency and used the iperf command to test the network bandwidth. The result shows that the latency is around 50ms and the network bandwidth is around 10 Mb/s. These values meet the requirements for both 2-Node vsan ROBO Cluster and vsan Stretched Cluster. Due to various factors in real environments, these values might change. Make sure they meet the requirements for 2-Node vsan ROBO Cluster or vsan Stretched Cluster. 4.8 VMware ESXi Server: Storage Controller Mode The storage controller supports both pass-through and RAID mode. It is recommended to use controllers that support the pass-through mode with vsan to lower complexity and ensure performance. If RAID is the only available mode, each disk should be configured as a standalone RAID-0 device. 4.9 Storage Policy Settings All HCIBench virtual machines use the vsan default storage policy. Table 4 shows the detailed settings of the storage policy used in the test. Table 4. Storage Policy Settings RULE NAME VALUE Number of Failures to Tolerate (FTT) 1 Number of disk stripes per object 1 Force provisioning No Object space reservation (%) 0 Flash read cache reservation (%) 0 Disable object checksum Failure tolerance method No RAID-1 (Mirroring)-Performance IOPS limit for object HCIBench Profile 29

30 We use HCIBench to generated I/O load and collect testing performance data. Users can set different HCIBench profiles to test storage performance with different workloads. We use a typical HCIBench profile that has the following settings as shown in Table 5. Table 5. HCIBench profile settings CONFIGURABLE FIELD VALUE Number of VMs 25 Number of data disk 1 Size of data disk 100GB Working-set percentage (%) 10 Number of threads per disk 2 Block size 4K Read percentage (%) 70 Random percentage (%) 70 I/O rate Unlimited Test time (seconds) 3,600 Warm-up time (seconds) 1,800 Initialize storage before testing 4.11 Advanced Settings of vsan None Dom Owner Force Warm Cache The vsan DOMOwnerForceWarmCache setting can be configured to force reads on both Node 1 and 2 in a 2-Node configuration. This is useful for 2-Node vsan ROBO Cluster because it can improve performance when virtual machines migrate. Meanwhile, it will not introduce any read latency since two nodes are physically located together. Do not force the cache to be read across Stretched Cluster sites as this will introduce additional read latency across the inter-site link. As such, we recommend enabling this setting (set value to 1) in a 2- Node vsan ROBO Cluster while keeping the default value (set value to 0) in a vsan Stretched Cluster. To check the status, run the following command on each ESXi host: esxcfg-advcfg -g /VSAN/DOMOwnerForceWarmCache To set it for 2-Node clusters: esxcfg-advcfg -s 1 /VSAN/DOMOwnerForceWarmCache 30

31 For more details, see Read Locality in Hybrid 2-Node vsan. 31

32 5. Solution Validation In this section, we present the test methodologies and processes used in this document. 32

33 5.1 Overview We tested the following solution cases: Baseline performance of 2-Node vsan and Stretched Cluster with witness in on-premises data center Performance testing of 2-Node vsan and Stretched Cluster with witness in on-premises data center with injected failures Performance testing of 2-Node with witness in vcloud Air Performance testing of 2-Node with witness in vcloud Air with injected failures Performance testing of Stretched Cluster with witness in vcloud Air Performance testing of Stretched Cluster with witness in vcloud Air with injected failures 5.2 Performance Data Collection Tools We used the following testing and monitoring tools in this solution: vsan Observer vsan Observer is designed to capture performance statistics and bandwidth for a VMware vsan Cluster. It provides an in-depth snapshot of IOPS, bandwidth and latencies at different layers of vsan, read cache hits and misses ratio, outstanding I/Os, and congestion. This information is provided at different layers in the vsan stack to help troubleshoot storage performance. For more information about the VMware vsan Observer, see the Monitoring VMware vsan with vsan Observer documentation. vsan Performance Service Performance Service collects and analyzes performance statistics and displays the data in a graphical format. vsan administrators can use the performance charts to manage the workload and determine the root cause of problems. When the vsan Performance Service is turned on, the cluster summary displays an overview of vsan performance statistics, including IOPS, throughput, and latency. vsan administrators can view detailed performance statistics for the cluster, for each host, disk group, and disk in the vsan Cluster. HCIBench HCIBench stands for "Hyper-converged Infrastructure Benchmark". It is essentially an automation wrapper around the popular and proven Vdbench open source benchmark tool that makes it easier to automate testing across an HCI cluster. HCIBench aims to simplify and accelerate customer POC performance testing in a consistent and controlled way. The tool fully automates the end-to-end process of deploying test VMs, coordinating workload runs, aggregating test results, and collecting necessary data for troubleshooting purposes. HCIBench is not only a benchmark tool designed for vsan, but also can be used to evaluate the performance of all kinds of Hyper-Converged Infrastructure Storage in vsphere environment. For details about HCIBench, refer to the HCIBench Page on VMware Fling. 5.3 Performance Comparison between Witness in vcloud Overview In this section, we conducted two sets of performance tests. Firstly, the 2-Node vsan ROBO Cluster was configured with a witness appliance in local on-premises data center. Secondly, the local witness was removed out of the cluster and a witness appliance in vcloud Air was added to this cluster. Get the performance data and compare it to that with witness in local. 33

34 In addition to the basic performance test, we also injected some failures deliberately to prove that vsan is robust to hardware failures regardless of placing witness appliance in vcloud Air or in local. Test Scenarios Baseline test In the baseline test, we ran the I/O test with HCIBench for one hour without any errors injected during the test. Additional 30-minute warm-up time was added before tests. The values of HCIBench parameters are defined in the Solution Configuration section. SSD failure test In the SSD failure test, we ran the HCIBench workloads for an hour. During the test, we injected a permanent disk error into the SSD on one of the two nodes. The injection occurred 30 minutes after the test was initiated. Note that if an SSD was down, the whole disk group would be down as well. Then all the IOs moved to the other healthy node. HDD failure test In the HDD failure test, the HCIBench workloads were also running for an hour. During the test, we injected a permanent disk error to one of the hard disks. The injection occurred 30 minutes after the test was initiated. Since this was a permanent error, vsan would start to rebuild the affected components onto other hard disks immediately after the error was detected. Witness appliance failure test In the witness appliance failure test, the HCIBench workloads were also running for an hour. The witness host was powered off 30 minutes after the test was initiated. Since two vsan nodes were both healthy, vsan can still function properly. VMware vsphere vmotion and host maintenance test In this test, we only put the physical node into maintenance mode but not the witness appliance. All the HCIBench workload virtual machines were distributed evenly on the two nodes. To put a host into maintenance mode, we must vmotion all the virtual machines from one host to another host first. We started the vmotion 20 minutes after the test was initiated. After vmotion was completed, we put that host into maintenance mode immediately. After the host was in maintenance mode for 10 minutes, we made that host exit maintenance mode. All these actions could be done during the one-hour test. Test Results 34

35 Figure 18. IOPS of vsan 2-Node Performance Test Figure 18 shows the IOPS result of 2-Node vsan performance test, including all the failure scenarios. In the figure, the legend local means placing the witness appliance in local on-premises data center. The legend vcloud Air means placing the witness appliance in vcloud Air. Based on the result, we concluded that: Placing witness in vcloud Air was fully supported because the performance was better than the worst case. A 2-Node vsan ROBO Cluster with witness appliance in vcloud Air could handle various hardware failures and the failures had minimal impact on vsan performance. In fact, the performance with the witness in vcloud Air was better than that with witness in local. The reason was that we emulated the network between local witness and a ROBO site to 500ms latency and 1.5 Mb/s bandwidth, which was the worst case. The reason we used the worst case scenario for the baseline performance data, was that the latency and bandwidth between vcloud Air and the ROBO site varied between environments and varied from time to time. Any other emulated network latency and bandwidth were not suitable for comparison from the perspective of methodology. The actual measured latency and bandwidth between vcloud Air and the ROBO site in our test were around 50ms and around 10 Mb/s. Thus, the performance with the witness in vcloud Air should be better than that with witness in local as expected. 5.4 Performance Comparison between Witness in vcloud In this section, we conducted two sets of performance tests. Firstly, the vsan Stretched Cluster was configured with a witness appliance in a local on-premises data center. Then, the local witness was removed out of the cluster and a witness appliance in vcloud Air was added to this cluster. This allows us to capture vcloud Air witness performance data and compare it to that with witness in the local site. In additional to the basic performance tests, we also injected some deliberate failures to prove that vsan is robust against hardware failures regardless of witness location. Test Scenarios The test scenarios were the same as those used in the 2-Node vsan test. Test Results Figure 19. IOPS of vsan Stretched Cluster Performance Test 35

36 Figure 19 shows the IOPS result of vsan Stretched Cluster performance testing, including all the failure scenarios. In this figure, the legend local means placing the witness appliance in the local onpremises data center. The legend vcloud Air means placing the witness appliance in vcloud Air. Based on the result, we conclude that: Placing the witness in vcloud Air does not result in any performance degradation. A vsan Stretched Cluster with its witness appliance in vcloud Air could handle various hardware failures with minimal impact on vsan performance. The performance when running the witness in vcloud Air was in fact even better than that with the witness in a local environment. That is likely due to the emulated network between local witness and each Stretched Cluster site being configured to 200ms latency and 2 Mb/s bandwidth, which was the worst case while remaining in a supportable configuration. The reason we used the worst case scenario for the baseline performance data, was that the latency and bandwidth between vcloud Air and the Stretched Cluster site varied between environments and varied from time to time. Any other emulated network latency and bandwidth were not suitable for comparison from the perspective of methodology. The actual measured latency and bandwidth between vcloud Air and the Stretched Cluster site in our test were around 50ms and around 10 Mb/s. Thus the performance with the witness in vcloud Air should be better than that with witness in local, as expected. 36

37 6. Conclusion This section summarizes how the solution reference architecture confirms that both 2-Node vsan ROBO Cluster and vsan Stretched Cluster support running a witness appliance in vcloud Air. 37

38 6.1 Conclusion This solution validates the supportability of placing the vsan witness appliance in vcloud Air for both 2-Node vsan ROBO Cluster and vsan Stretched Cluster. The performance tests also show that placing the vsan witness appliance in vcloud Air has no performance impact on 2-Node vsan ROBO Cluster or vsan Stretched Cluster. The failure injecting tests show that vsan is robust to failures and the performance is minimally affected in failure scenarios with the witness appliance in vcloud Air. Meanwhile, placing the vsan witness appliance in vcloud Air brings users the advantages of public cloud, which is easy to scale out and easy to manage. In sum, this solution reference architecture confirms that both 2-Node vsan ROBO Cluster and vsan Stretched Cluster support running a witness appliance in vcloud Air and the performance will not be impacted by witness location. 38

39 7. Reference This section lists the relevant references used for this document. 39

40 7.1 White Paper For additional information, see the following white papers: VMware vsan 6.2 for Remote Office and Branch Office Deployment 7.2 Product Documentation For additional information, see the following product documentation: vsan Management VMware vsan 6.2 Stretched Cluster and 2-Node Guide VMware vsan 6.2 Network Design Guide 7.3 Other Documentation For additional information, see the following document: VMware Compatibility Guide 40

41 8. About the Author and Contributors This section provides a brief background on the author and contributors of this operation guide. 41

42 8.1 About the Author and Contributors Victor Chen, Solution Architect in the Product Enablement team of the Storage and Availability Business Unit, wrote the original version of this paper. Catherine Xu, Technical Writer in the Product Enablement team of the Storage and Availability Business Unit, edited this paper to ensure that the contents conform to the VMware writing style. 42