What is VMware vSAN

VMware Virtual SAN or we call it vSAN which was introduced back in 2013. In simple words, if I would say, vSAN is a software-based distributed storage solution that pools together direct-attached storage devices across a VMware vSphere cluster to create a distributed, shared data store. You can also refer to it as hyper-converged or can consider it as software-defined storage and some even referred to it as hypervisor converged at some point. VMware vSAN is fully integrated with VMware vSphere. There is a very simple configuration required for configuring vSAN. If you know how to enable HA and DRS, then you know how to configure vSAN. Of course, you will need to have a vSAN Network, and you achieve this by creating a VMkernel interface and enabling vSAN on it. vSAN works with L2 and L3 networks, and as of vSAN 6.6 no longer requires multicast to be enabled on the network. If I will go through with a quick overview of vSAN, here it is.

Overview of VSAN:-

• VSAN pools the locally attached storage from members of a VSAN–enabled cluster and presents the aggregated pool back to all hosts within the cluster.
• It has multiple disks presented to multiple hosts
• VSAN does not require any additional software installations.
• It is built directly into ESXi itself. Managed from vCenter Server.
• VSAN is compatible with all the other cluster features that vSphere offers, such as vMotion, HA, and DRS.
• We can even use Storage DRS to migrate VMs on or off a VSAN datastore.
• VSAN uses the disks directly attached to the ESXi hosts and is simple to set up.
• VSAN uses the concept calling RAIN or a reliable array of independent nodes.
• VSAN uses a combination of vSphere APIs for Storage Awareness (VASA) and storage policies to ensure that VMs are located on more than one disk and/or host to achieve their performance and availability requirements.
• VMware recommends 10 Gbps networking between ESXi hosts when using VSAN.

Requirements for VSAN:-

• ESXi 5.5 or newer hosts
• vCenter 5.5 or newer
• One or more SSDs per host
• One or more HDDs per host for hybrid mode
• Storage controllers must be on the VSAN HCL
• Minimum of three hosts per VSAN cluster
• Maximum of 64 hosts per VSAN cluster
• 1 Gbps network between hosts (10 Gbps highly recommended)

Types of VSAN Configuration

• Hybrid
• All SSD(Flash Only Disconnect)

 Hybrid:

• It uses both SSD and magnetic hard disks.
• VSAN requires at least one flash-based device in each host.
• Hybrid VSANs use the SSD as a read and write cache just as some external SANs do.
• When blocks are written to the underlying datastore, they are written to the SSDs first, and later the data can be relocated to the (spinning) HDDs.
• VSAN’s read/write cache ratio is 70% read, 30% write.

All SSD:

•  It uses all SSD Disks.

There are many reasons why customers are more interested in choosing VSAN for their SDDC environment. Here are a few of them:

• Integrated with vSphere which becomes more easier to manage and use existing tools
• Provides deduplication and data encryption
• Low Latency
• Lowering the CAPEX
• Enable fast delivery of services in less human efforts
• Save unsed storage from ESXi
• Easy to migrate to Cloud
• Low Risk
• High Controlling
• Simplify Day to Day Management
• Reduce TCO
• Automation
• Availability
• Security
• Reliability
• Scalability
• Management

There are two types of deployment mode in VMware vSAN:

• Hybrid Mode
• All-Flash Mode

Hybrid Mode:

In the hybrid mode of deployment, we will use all magnetic disks. However, you must have one SSD disk for caching used. It means you should have 1 SSD disk and the rest will be a magnetic disk.

All-Flash Mode:

In all-flash mode, all disks must be SSD. Out of all disks, you will use 1 disk for caching purposes, and the rest will be for disk pool.

Points to Remember for VMware vSAN:-

• VMware VSAN works on a cluster basis.
• In a single cluster, there can be a maximum of 5 Disks groups.
• In each disk group, there can be a maximum of 7 disks for data control and 1 disk for caching used. It means you can have 8 disks in each disk group.
• Every disk group must have 1 SSD disk.
• There must be at least 3 ESXi hosts in a cluster.
• There can be a maximum of 64 ESXi hosts in a cluster if you are using vSphere 6. x environment
• You enable VSAN on the VMware cluster.

The calculation for Maximum Disks:

• Total Maximum Disk in a Cluster in Hybrid Deployment: (1 SSD + 7 Magnetic) X 5 Disk Groups
• Total Maximum Disk in a Cluster in Hybrid Deployment: (1 SSD + 7 SSD) X 5 Disk Groups