What is Virtual SAN?

Canadian Web Hosting recently launched new VMware based Private Cloud plans in Canada using VMware’s Virtual SAN storage technology that deliver cutting-edge technologies at a fraction of the cost. Virtual SAN represents a strategic shift in enterprise storage as it utilizes distributed storage running on commodity hardware and drives that significantly reduces capital expenditures, while also giving users top tier performance and the same enterprise grade reliability that many of us have come to expect from VMware.   So what is Virtual SAN and how will work for your business?

VMware Virtual SAN is a scale out storage solution that utilizes the local storage of the ESXi hosts, and presents a single data store to the private cloud or server cluster.  Driven by Storage Profiles, the options for VM performance and redundancy are on a per-VM basis.

vmware vsan

What Virtual SAN consists of:

  • ESXi hosts
  • vCenter 5.5 or 6.0
  • Virtual SAN Network – VMkernel port group on 1GB or 10GB (preferred) NICs
  • Disk Groups – a collection of a single SSD and up to 7 HDDs
    • Up to 5 Disk Groups per VMware host
    • SSD should be at least 10% of HDD capacity in Disk Group
  • Highly Available Cluster
  • Storage Profiles

How does it work?

As a high level overview, VMware’s Virtual SAN leverages the local storage of each host and combines it into a single data store, which is shared among all hosts in the cluster.  The hard drives are all presented individually to the host.  So, the setup includes a controller that supports JBOD or pass-through, so ESXi can see each individual disk.

The SSD hard drives in each disk group are not used for capacity, but is used for cache.  The ratio is 70% for read cache and 30% for write cache.  All the writes are directed to the SSD hard drives where the writes are then de-staged to the hard drives later. If a block gets requested which is not in the read cache, the request is then directed to the hard drive.

The images below include an example of how the read/write works:

  • First write to SSD cache and then to HDD
  • First read from SSD cache and then if the block isn’t there, read from HDD

vmware vsan

Redundant Array of Independent Nodes

It’s important to note that Virtual SAN does not leverage RAID like traditional storage services instead it uses a RAIN (Redundant Array of Independent Nodes).   It works when RAIN is implemented to increase fault tolerance in a cluster. The storage clusters can be managed through a centralized management interface (vSphere). The management software then builds a virtual pool of storage devices without requiring the physical presence of network and storage administrators. The RAIN management software with vSAN automatically detects any new server nodes and allows them to communicate with each other.  In case of a node failure, the lost data is replicated among other RAIN nodes in a cluster to avoid immediate replacement of the failed node.   RAIN-based grids are more resilient to application workload changes through effective load-balancing features.

Storage Policies

When a VMware Private Cloud with Virtual SAN is setup one of the first steps customers will do is to define their storage policy.  VM storage policies are defined before you start deploying your VMs.  At this time, you can decide if you need availability, or performance (striping) including reserving read cache, and whether you want to use thin or thick provisioning.  By default, the Private Cloud Virtual SAN does thin provisioning, but that can easily be overridden by your storage policy.

By using variables defined in our storage profiles, we can assign each VM to withstand 1 or more disk failures, or 1 or more host failures, ensuring redundancy and uptime.

The storage profiles will also allow us to define the number of HDDs that the VM will reside on. By striping the VM across multiple HDDs, we can increase performance for data that doesn’t currently reside in read cache.

Benefits of Virtual SAN:

  • Simple storage designed for virtual machines
  • Significantly lower TCO than systems with comparable performance
  • Granular, linear scaling of performance, capacity and cost, enabling you to start small with a low upfront investment and grow as you go
  • Rapid storage provisioning and automated, selftuning ongoing management
  • Support from VMware and all major server OEMs
  • “Single pane of glass” management with VMware vSphere Web Client

Read more about VMware’s Virtual SAN here.

Find out more about Canadian Web Hosting’s Private Cloud plans by calling 1-888-821-7888 or emailing sales@canadianwebhosting.com today!

About Canadian Web Hosting

Since 1998, Canadian Web Hosting has been providing on-demand hosting solutions that include Shared HostingVirtual Private Servers (VPS), Cloud Hosting, Dedicated Servers, and Infrastructure as a Service (IaaS) for Canadian companies of all sizes. Canadian Web Hosting is SSAE 16 Type II SOC 2 certified, ensuring that their processes and business practices are thoroughly audited against industry standards. Canadian Web Hosting guarantees a 100% network uptime, and a total money-back guarantee that backs everything they do. Customers can get help by calling 1-888-821-7888 to get 24/7 support. For more information, visit them at www.canadianwebhosting.com, or get the latest news by following them on Twitter at @cawebhosting.

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