A "Witness" is a special VM that monitors the Metro Availability configuration health. The Witness resides in a separate failure domain to provide an outside view that can distinguish a site failure from a network interruption between the Metro Availability sites.
vSAN is enterprise-class, storage virtualization software that, when combined with vSphere, allows you to manage compute and storage with a single platform. With vSAN, you can reduce the cost and complexity of traditional storage and take the easiest path to future ready hyperconverged infrastructure and hybrid cloud.
A file share witness is an SMB share that Failover Cluster uses as a vote in the cluster quorum. This topic provides an overview of the technology and the new functionality in Windows Server 2019, including using a USB drive connected to a router as a file share witness.
VMware vSAN uses a software-defined approach that creates shared storage for virtual machines. It virtualizes the local physical storage resources of ESXi hosts and turns them into pools of storage that can be divided and assigned to virtual machines and applications according to their quality-of-service requirements.
What is a mandatory requirement for a vSAN stretched cluster? The desired configuration should be able to survive a single failure. Which configuration satisfies the design requirements? A new vSAN cluster needs to run 900 VMs and protect against one failure.
A vCenter HA cluster consists of one Active node that serves client requests, one Passive node to take the role of Active node in the event of failure, and one quorum node called the Witness node. The other two nodes in the cluster dynamically assume the roles of Active and Passive nodes.
Object-Based StoragevSAN stores and manages data in the form of flexible data containers called objects. An object is a logical volume that has its data and metadata distributed across the cluster. For example, every VMDK is an object, as is every snapshot.
A vSAN datastore contains the following object types: VM Home Namespace. The virtual machine home directory where all virtual machine configuration files are stored, such as . vmx, log files, vmdks, and snapshot delta description files.
By default VSAN. ClomMaxComponentSizeGB is set to 255GB. When Virtual SAN stores virtual machine objects, it creates components whose default size does not exceed 255 GB.
Click on Edit Virtual Machine Settings, either on the Summary View for that Virtual Machine (VM) or by going to the VM Menu, then Settings. Once inside the VM Settings, click on the Options tab, then select Startup/Shutdown. From there, you will need to change the account that the VM will start under.
If multiple hosts exist in a data site, then vSphere HA fails over the virtual machines on the failed host to other hosts in the same site. If the site contains a single host, then vSphere HA fails over the virtual machines to a host on the remaining data site.
If you want to leverage RAID 6 erasure coding polices, the following requirements must be met:
- vSAN Advanced license.
- The hosts in the cluster must use all-flash storage.
- The cluster must have at least 6 hosts.
- On-disk format version 3 or later for RAID 5/6 polices.
vSAN reduces the total cost of ownership by up to 50% by eliminating traditional hardware storage costs with intelligent software-defined storage that accelerates the shift to server economics, affordable flash, and the broadest selection of x86 platforms for HCI.
A cluster in vSphere is a collection of ESXi hosts configured to share their resources. Clusters are used to enable some of the more powerful features in vSphere, such as High Availability (HA), Distributed Resource Scheduler (DRS), Fault Tolerance (FT), and vMotion.
The primary benefit of a stretched cluster solution is to enable active-active and workload balanced data centers. The solution has the ability to migrate virtual machines between sites, which enables cross-site mobility of workloads.
Fault domains enable you to protect against rack or chassis failure if your vSAN cluster spans across multiple racks or blade server chassis. A fault domain consists of one or more vSAN hosts grouped according to their physical location in the data center.
This cluster is located in two geographical locations. In a stretched cluster configuration, both sites are active sites. If one or the other site fails, VMware vSAN uses the storage on the other site and VMware vSphere HA restarts any VM which was running on the failed site, on the remaining active site.
VMware Site Recovery Manager (SRM) is a disaster recovery orchestration product that protects virtual machines by duplicating them to a secondary site. This is achieved using storage array-based replication or vSphere Replication network-based replication.
Each host that contributes storage in a vSAN cluster will contain at least 1 disk group. Disk groups contain at most 1 cache device and between 1 to 7 capacity devices. At most a vSAN host can have 5 disk groups, each containing up to 7 capacity devices, resulting in a maximum of 35 capacity devices for each host.
Stretch is the difference between the best possible path through the network and the actual path the traffic takes through the network.
Overview of Stretched Storage in SRMVMs are shut down and restarted on the target site. The Recovery Point Objective is not guaranteed to be zero. SRM attempts to synchronize any changes during a failover, but in the case of a site loss of the source it may not be possible.
