Feb 5, 2015

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











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