Vmware Virtual SAN - vSAN Architecture

1. Overview

• Software-defined storage software solution.

• Aggregates locally attached storage from each ESXi host in a cluster.

• Flash optimized storage solution.  

• VM-Centric data operations and policy driven management principals.

• Resilient design based on a Distributed RAID architecture

• No single points of failures

• Fully integrated with vSphere.

• Virtual SAN is NOT a Virtual Storage Appliance

• Virtual SAN is fully integrated with vSphere (ESXi & vCenter)

• Drivers embedded in ESXi 5.5 contain the Virtual SAN smarts

• Kernel modules:

• Provide the shortest path for I/O

• Remove unnecessary management overheads when dealing with an appliance

• Do not consume resources unnecessarily

• VSAN:

• Hybrid storage solution

• Magnetic disks (HDD)

• Flash based disks (SSD)

• Storage scale out architecture built into the hypervisor

• Dynamic capacity and performance scalability

• Object based storage architecture

• Interoperable with vSphere and enterprise features:

• vMotion, DRS, vSphere HA 

2. Hardware Requirements

• Boot Devices

• Depends on amount of host memory

• Up to 512 GB

• Use SD/USB devices as the installation media.

• 512 GB or greater

• Use a separate magnetic disk or solid stated disk as the installation device
• In Virtual SAN ALL read and write operations always go directly to the Flash tier.
  
  • Flash based devices serve two purposes in Virtual SAN
  • Non-volatile Write Buffer (30%)
  • Writes are acknowledged when they enter prepare stage on SSD.
  • Reduces latency for writes
  • Read Cache (70%)
  • Cache hits reduces read latency
  • Cache miss – retrieve data from HDD
   

3. Documents

VMware vSAN Technical Walkthrough Deep Dive

Vmware vSA N Understand Choice Storage

VMware vSAN Design and Sizing

VMware vSAN Overview

VMware vSAN Technical