Azure Classroom Series – 28/Aug/2020

Ephemeral OS disks

  • Lets understand Stateless and Stateful Applications

  • A Stateful application saves data (client_data) about application in the same machine. Preview

  • A Stateless application doesn’t save data (client data) about application in the same machine Preview

  • In stateful applications whenever servers scale up or down, then there will be need for local storage.

  • Stateless applications are designed to scale, Scaling up or down doesn’t really matter

  • Stateless applications are designed for performance & it doesn’t matter if the local storage is lost when the machine is terminated/removed as the state is stored externally.

  • Azure gives option for the OS disks to be ephemeral (lost when vm is deleted) just like temp disks for stateless application architectures, These disks are called as ephemeral os disks.

  • As of now Ephemeral Os Disks can be stored on temp disks (Preview)

  • So in azure we have two kinds of Os disks

    • Persistent Os Disks
      • Vm Sizes Supported: all vm sizes
    • Ephemeral Os Disks
      • Vm Sizes Supported: Premium storage such as DSv1, DSv2, DSV3, Fs, FSv2, GS, M
  • Before we understand further about managed disk, lets also try to understand un-managed.

  • To understand un managed disks, we need to understand about Azure Storage Accounts

Azure Storage Account

  • This is a service which contains all of Storage Objects
    • blobs
    • files
    • queues
    • tables
    • disks
  • Data in Azure Storage account is durable, highly available, accessible from any where in the world over HTTP(s)
  • Storage account provides number of storage services
    • Blobs: Provides a highly scalable service for storing data objects such as text or binary data
    • Tables: Provides a NoSQL style store for storing structured data.
    • Queues: Provides a reliable messaging queues b/w application components
    • Files: Provides managed file shares that can be used by Azure VMs or on-premise servers
  • There are three types of storage blobs
    • Block Blobs:
      • To store any files (text/image/video/mp3) etc on Azure.
    • Append Blobs:
      • They are used for log files
    • Page Blobs:
      • They are used to store VHD (Virtual Hard disk) files when deploying unmanaged disks.
  • Performance Tiers: While creating storage accounts we can choose b/w Standard & Premium Performance Tiers
    • Standard: This tier supports all storage services (blobs, tables, files, queues)
    • Premium: They only support page blobs & they support only one replication option (LRS)
  • Replication Options:
    • Local Redundant Storage (LRS): Makes three synchronous copies of your own data within a single data center.
    • Zone redundant Storage (ZRS): Makes three synchronous copies of your own data across multiple availability zones within a region
    • Geographically Redundant Storage (GRS): Same as LRS, plus three additional asynchronous copies to other region.
    • Read Only Geographically Redundant Storage (RA-GRS): Same as GRS, plus you have read-only access to data in other region
  • Create a Storage Account using Azure Portal Refer Here Preview Preview
  • Exercise: Create a Storage Account by looking into all the possible options and make note of options.

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