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What the editor wants to share with you this time is how to get started with vSAN in vmware. The article is rich in content. Interested friends can learn about it. I hope you can get something after reading this article.

First, background introduction

1. Briefly introduce the shared storage background of vsphere.

An important function in vSphere is to encapsulate a virtual machine. A virtual machine exists in the form of a file and can be copied arbitrarily, such as .vmx virtual machine configuration file, vmdk data file, etc.

There is also a concept of cluster under vSphere. A cluster is regarded as a resource pool with many advanced features of vSphere. Business can be on any host in the cluster without having to worry about the failure of a single host.

As shown in the following figure, vSphere's fault recovery mechanism, HA, can migrate virtual machines on failed hosts to other hosts to run.

But there is a premise of this feature is shared storage, a storage can be connected by multiple servers at the same time, read data at the same time, any node failure, the data is not affected, and other servers can use these data to quickly restore business.

Dual-head redundant storage is as follows:

2. Simple comparison between shared storage and distributed storage

Local storage has always been famous for its high reliability, good stability and rich functions, but it is easy to form a data isolated island due to its poor scalability, high price and difficult data connectivity, which leads to high data center management and maintenance.

Distributed storage: data is distributed on multiple independent devices on the network, generally using standard x86 servers and network interconnection, and running relevant storage software, such as vSAN, on which the system provides storage services as a whole.

II. Brief introduction of vSAN

1. Official introduction

What is vSAN can be understood as software-defined distributed storage based on server clusters.

The management program of storage is realized by software. only software can be developed, flexible and fast, and can adapt to the various needs of enterprises for storage. Distributed data and IO access can be distributed to multiple nodes, so that the capacity and performance of the whole storage system increases linearly with the increase of nodes.

The figure is as follows:

VMware vSAN aggregates local or directly attached data storage devices and creates a single storage pool that is shared among all hosts in the vSAN cluster. VSAN eliminates the need for external shared storage and simplifies storage and virtual machine configuration.

VSAN is a distributed software layer included in the ESXi hypervisor, which is fully integrated with VMware vSphere. VSAN supports vSphere features that require shared storage, such as high availability (HA), vMotion, and distributed resource scheduler (DRS). VM storage policies enable you to define virtual machine storage requirements and functions.

Each host in the vSAN cluster can provide storage for the cluster. These storage devices are combined to create a single vSAN data store. Hybrid vSAN clusters use flash devices as the cache layer and magnetic drives use the capacity layer. The all-flash vSAN cluster uses flash devices for the cache layer and capacity layer. The architecture creates flash memory optimization designed for virtual environments and flexible shared data storage.

2. VSAN concept

One of the key elements of software-defined storage is storage policy-based management (storage policy-based manage-ment,SPBM), when one of the vSAN features, through SPBM and vsphere API, the underlying storage technology is represented as an abstract pool of storage space with multiple functions and presented to administrators for deployment.

You can configure a hybrid cluster or an all-flash cluster, in which flash memory is used for caching, disks for capacity, and flash memory for both cache and capacity in an all-flash cluster. (the combination of cache and capacity makes storage performance better, and all-flash is faster.)

Local storage device, must have at least one flash cache device and one capacity device

Each node needs to provide storage resources, access resources and management procedures.

A 10 Gigabit Ethernet switch is generally required

The devices on the host will form one or more disk groups, each containing a flash cache device and one or more persistent storage capacity devices. Multiple disk groups can be configured on each host

3. VSAN functions and features

Properties:

Built into the vsphere kernel, vSAN is implemented within the vSphere kernel and seamlessly integrated with vSphere to help optimize performance and reliability of read / write (Imax O) caching. VSAN accelerates the speed of read / write disk Imax O through the built-in cache in server-side flash memory, minimizing storage latency and built-in fault protection. This technology uses distributed RAID and cache mirroring to ensure that data non-disruptive capacity scalability is never lost when disks, hosts, or networks send failures. By adding hosts to the cluster or adding disks to hosts, vSAN data capacity can be easily non-disruptively extended. Virtual machine-centric policy-based management The solution uses policy statements that automatically convert to system configuration to reduce storage requirements associated with individual virtual machines or virtual disks, and with this approach, any IT can immediately provision storage to strictly comply with service level agreements (service-level agreement,SLA). By self-adjusting storage and dynamic storage load balancing, vSAN automatically maintains the specified storage capacity, performance and availability level for each virtual machine without interruption. This technology can interoperate with VMware vSphere Distributed Resource Scheduler to achieve end-to-end technology and storage load balancing. Integrated with vSphere data services, the solution leverages vSphere snapshots, clones, VMware vSphere Data Protection and vSphere Replication to provide data protection, backup, fast cloning and data transfer across clusters or sites for disaster recovery and vSphere web client integration with extensive hardware compatibility and HORIZON VIEW and VMware vCenter site Recovery Manager interoperability. The solution can be deployed with horizon view in a virtual desktop infrastructure (VDI) environment Deploy in a disaster recovery environment with vCenter Site Recovery Manager

Features:

Shared storage support, vSAN supports VMware features that require shared storage, such as HA, vMotion, and DRS. For example, if a host is overloaded, DRS can reduce virtual machines and migrate to full disk clusters (JBOB) on other hosts in the cluster, supporting the use of JBOB in blade server environments. If your cluster contains blade servers, you can use JBOB storage connected to blade servers to expand data storage capacity full flash and hybrid configuration disk format VSAN6.6 supports disk virtual file format 5.0. this format provides highly extended snapshots and clone management support for failure domains by vSAN clusters, and vSAN supports configuration of failure domains. When vSAN clusters have multiple racks or blade server chassis in the data center, they can prevent hosts from rack or chassis failures. VSAN supports extended clusters, which can be vSAN Health Service across two address locations. Includes some preconfigured health check tests to perform health and troubleshooting and diagnose the cause of problems with cluster components, and to identify any potential risks to vSAN performance services, including statistical charts for monitoring IOPS, throughput, latency, and congestion. The ability to monitor the performance of vSAN clusters, hosts, disk groups, disks, and virtual machines is integrated with vSphere storage capabilities, typically with vSphere data management functions for VMFS and NFS storage, which include snapshots, linked clones, vSphere Replication and vSphere APIs for data protection virtual machine storage policies, and domain virtual machine storage policies to support virtual machine-centric storage management methods such as US allocation The default storage policy of vSAN is automatically lowered and assigned to virtual machine quick provisioning. During creation and deployment, vSAN can quickly provision storage in vCenter server.

4. Several nouns and terms about vSAN

Pooling

The connection between the connection servers inside the stand-alone

Fault domain

In order to ensure that the data is not lost and repaired, the location of the data is required. The same data of the same virtual machine must be saved on different hosts.

If a machine breaks down, the arbitration mechanism is needed to ensure that only one piece of data is active and up-to-date, otherwise it will cause conflict.

This is the simplest architecture of vSAN, which allows only one host to fail, as long as the fault is sent in one host.

The following is a simple indication of the vSAN fault domain. There is a word in vSAN called FTT (Fault to tolerance), which allows the maximum number of hosts to fail at the same time. The virtual machine data protection level determined by FTT also determines the minimum number of hosts required for a cluster.

Differentiated service

Storage policies can be used to distinguish different services for different objects.

For example:

Virtual machine 1 sets storage policy A (FTT=1, does not reserve cache, limits IOPS to 100) virtual machine 2 sets storage policy B (FTT=2, reserves 10% ssd cache, does not limit IOPS)

Disk group

Disk groups are physical storage capacity units on hosts and physical device groups that provide performance and capacity for vSAN clusters. Devices are organized in the form of disk groups on each esxi host where the vSAN cluster provides its local devices.

Each disk group must have one flash cache device and one or more capacity devices

At least one SSD+1~7 fast HDD per disk group, and no more than 5 disk groups per host

The devices used for caching cannot be shared between disk groups or for other purposes, and a single cache device must be dedicated to a single disk group. In a hybrid cluster, flash devices are used for the cache layer and disks are used for the storage capacity layer.

It is recommended to use multiple disk groups to disperse data, because, for example, a ssd failure will cause disk group data to be inaccessible, and decentralized data can effectively reduce the impact of this failure.

All capacity

"all capacity refers to the physical capacity used by one or more virtual machines at any time, which is determined by a number of factors, including the capacity technology cache size used by VMDK, including replicas, etc., regardless of the capacity used to include replicas."

Object-based storage

1) vSAN stores and manages data in the form of flexible data containers, that is, objects, whose data and metadata are distributed in logical volumes in the cluster. For example, each VMDK, each snapshot is also an object. When a virtual machine is installed on the vSAN data store, vSAN creates a set of objects composed of multiple components for each virtual disk.

2) based on the allocated virtual machine storage policy, vSAN sets up and manages each object separately, and may also be designed to create a RAID configuration for each object

3) when vSAN creates objects for virtual disks and determines how to distribute objects in the cluster, the following factors will be taken into account:

A, vSAN confirms that virtual disk requirements have been applied according to the specified virtual machine storage policy settings

B and vSAN confirm that the correct cluster resources are used for provisioning. For example, vSAN determines the number of replicas to be created based on the protection class, and the performance policy determines the amount of Flash Read Cache allocated and the number of strips created for each replica, as well as where each replica is placed in the cluster.

C, vSAN continuously monitors and protects the policy compliance status of virtual disks, and if any non-compliant policy status is found, it is necessary to troubleshoot and resolve the underlying problem.

D. If necessary, you can edit the virtual machine storage policy settings. Changing the storage policy settings will not affect the virtual machine access. When changing the virtual machine storage policy settings, vSAN may start the object re-creation process, and then resynchronize the objects.

E, vSAN confirm that the required protection components (such as mirroring and certification) are on different hosts or fault-tolerant domains

VSAN data storage

1) when vSAN is enabled on the cluster, a separate vSAN data store is created, and a single vSAN data store can provide different service levels for each virtual machine or virtual machine disk.

1) specific features of vSAN data storage need to be considered

A, vSAN provides a single vSAN data store that can be accessed by hosts (with or without devices) in the cluster, and each host can mount any other data store, including Virtual Volume, VMFS, or NFS

You can use Storage vMotion to move virtual machines between vSAN data stores, NFS data stores, and VMFS data stores

C, disks and flash devices used for capacity only can provide data storage capacity, and devices used for flash caching are not counted as part of the data storage

D. In automatic disk declaration mode, when adding capacity hosts to the vSAN cluster, or adding capacity devices to any cluster member, vSAN data storage capitalization increases dynamically.

Objects and components

1) each object consists of a set of components, such as .vmx, log files, vmdk, snapshot incremental description files, etc.

2) the vSAN data store protects the following object types:

A, virtual machine home page command space

All virtual machine configuration files are stored in the virtual machine home directory, such as .vmx, log files, vmdk (vmdk disk description file fvmdk-lag is the disk file), snapshot incremental description files, and so on.

B 、 VMDK

Virtual machine disk or .vmdk file, used to store the contents of the virtual machine hard drive.

C, virtual machine exchange object

Create-SWDK file when the virtual machine is powered on

D, snapshot increment VMDK

Created when a virtual machine snapshot is generated

3) vSAN components are object blocks that look across multiple hosts in a machine to allow multiple failures to be sent simultaneously and meet performance requirements

4) vSAN uses distributed RAID architecture to distribute data to the whole cluster

5) two technologies are mainly used in the distribution of components:

Striped (RAID 0) mirror (RAID 1)

6) the number of component copies to be created is determined based on the object policy definition.

Virtual machine compliance status: compliance and non-compliance

When too many objects cannot meet the requirements of the assigned storage policy, the virtual machine is considered to be non-compliant. For example, if the mirror copy cannot be accessed, the state may become non-compliant. The requirements defined in the storage policy of the virtual machine domain are met, and the status of the virtual machine is compliant. In the physical disk placement tab of the virtual disk page, you can determine the compliance status of the virtual machine object

Component status: degraded and non-existent

Degraded, and if a permanent failure is detected and it is determined that it cannot be restored to the original working state, the component will be in the degraded state.

No, vSAN detected a temporary build failure, in which the component and its data can be recovered and vSAN can restore its original state, then the component does not exist. It may occur when the host is restarted or the device is unplugged from the vSAN host. After waiting for 60 minutes, vSAN will rebuild the component in the nonexistent state.

Object status: normal and abnormal

Depending on the type and number of failures that occur in the cluster, the object may be in one of the following states:

Normally, when at least the RAID1 image is available or the minimum number of required segments is available, the object is considered to be in a normal state.

Abnormal, if there is no full mirror available, or if the RAID5 or RAID6 object does not meet the minimum number of segments, the object will be considered abnormal. If the number of votes of an object is less than 50%, the object is abnormal, and if there are multiple failures in the cluster, it may cause the object to be abnormal and affect the availability of the virtual machine.

Prove

A component that contains only metadata and does not contain any actual application data can be used as a te breaker when you need to determine the availability of a normal data storage component if a potential failure is sent. If you use disk format 1.0, you will witness the use of 2mb space in vSAN data storage to store meta-elements, and if you use 2.0 or higher, it will take up 4mb space.

6.0and higher will maintain the arbitration by giving the non-voting system, where each component may use multiple votes to determine the availability of the object, and if more than 50% of the votes that make up the virtual machine storage object are made up, the vSAN data store will no longer be able to access the object, and the inaccessible object may affect the availability of the relevant virtual machine.

Striping

Striping is a technology that divides a continuous piece of data into many small parts and stores them on different disks, which enables multiple processes to access different parts of the data at the same time without causing disk rereading, and can obtain the maximum Iluno parallel capability of Chengdu when sequential access to such data is needed. In order to achieve very good performance.

The illustration is as follows:

Number of disk stripes per object

Number of hard disks spanned by each copy of the storage object

Storage Policy-based Management (SPBM)

When using vSAN, you can define the storage requirements of virtual machines in the form of policies, such as performance and possibility. VSAN ensures that at least one virtual machine storage policy is assigned to virtual machines that have been deployed to vSAN data storage. When you understand the storage requirements of virtual machines, you can define storage policies and assign them to virtual machines. If the storage policy is not applied when deploying virtual machines, vSAN will automatically assign the default vSAN policy. The number of failures allowed is mainly configured as 1, one disk tape per object, and a thin standby virtual disk. For best results, define your own virtual machine storage policy, even if your policy requirements are the same as those defined in the default storage policy.

Ruby vSphere console (RVC)

RVC, which provides a command line interface for managing and troubleshooting vSAN clusters, RVC provides cluster-wide attempts rather than host-centric attempts provided by esxcli, and bundling with vcsa does not require separate installation

VSphere PowerCLI

Added command line scripting support for vSAN to help automate configuration and management tasks

VSAN Observer

Is a web-based tool allowed on RVCS for inbound performance analysis and vSAN cluster monitoring. VSAN Observer allows you to view performance statistics of the capacity tier, statistics of physical disk groups, current load of CPU, usage of vSAN memory pools, and distribution of memory objects among vSAN clusters

5. The core idea of vSAN

Improve the utilization of existing resources, reduce the cost of operation and maintenance, improve the availability of hardware and applications, realize the flexibility of operation and maintenance, improve the manageability and security of the desktop

6. The main functions realized through vsphere web client

VMotion,DRS, HA and other advanced functions are based on this technology DRS dynamic resource allocation technology, so that virtual machines running in multiple physical servers can achieve load balancing. When a server load is detected near the threshold, it can be migrated online through vMotion technology. DPM distributed power management can combine DRS function to centralize multiple virtual machines with low load on a few physical servers, and turn off useless ones, thus saving power. When the load increases, power on the unused physical servers is powered on, and load balancing is realized through DRS. Storage vMotion storage online migration technology, allows running virtual machine storage resources to migrate from one storage device to another storage device data protection data protection function, can backup high availability of virtual machines, when a physical server failure, the affected virtual machines can be migrated to other servers FT fault tolerance, running on different physical servers running two exactly the same virtual machines Provide the highest level of redundancy. Even if a physical server fails, the terminal business will not run replication. You can copy all the images of the virtual machine to another site for disaster recovery to ensure data security. After reading this article on how to get started with vSAN in vmware, if you think the article is well written, you can share it with more people.

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