Components of VMware vSphere (Module 2 Pt.3 VMware vSphere Cluster Features)

  Data Center Virtualization, VMWare

vMotion

  • vMotion is a migration process
  • vMotion allows you to migrate a running VM from one ESXi host to another.
  • Can be used to load balance ESXi hosts in a cluster by moving VMs to a host with more available resources.
  • Allows you to perform hardware adjustments by moving all VMs to another host

How does this work

  • VMs are built on virtual hardware and are predominantly a large chunk of memory on an ESXi host
  • Just need to copy that memory from one host to another
  • Migration is very fault tolerant.  If something goes wrong, the original host remains in control.
  • Can operate without shared storage – can migrate even if the VMs do not use shared storage.

Distributed Resource Scheduler (DRS)

  • Monitors memory and CPU loads on ESXi hosts.
  • Upon VM Power up, DRS can recommend which Host to run the VM on, OR:
  • Using vMotion, can automate migration of VMs to another host that isn’t being as utilized based on usage and configuration settings (rules).
  • Using rules, some VMs can be bound together or forced apart (redundant clusters).
  • Upon VM Powerup, DRS can recommend which Host to run the VM on.

Distributed Power Management (DPM)

  • Leverages the automation of DRS to consolidate VMs on specific hosts, allowing low-use hosts to shut down and save power
  • Power can be restored using Wake On Lan or IPMI
  • On Power-up, DPM again leverages DRS to balance the ESXi hosts

Storage vMotion

  • Allows migration of a VMs hard drive from storage device to another.
  • Configures ESXi host to see both storage array, then I/Os are written to both source and mirrored disks.
  • Storage devices do not need to be the same, as long as they are both supported.
  • Can move VM from Shared device to Local Storage to perform maintenance on Shared while not disrupting the VM

Storage DRS

  • Load balances Disk I/O between storage units
  • Can be manually or automated

Storage I/O Control

  • Some applications may consume all I/O available, at the expense of others (Database Servers, busyEmail Servers)
  • Storage I/O Control makes sure some I/O is available for the lesser consuming applications to optimize performance.

vSphere Data Protection (VDP)

  • Image Based Backup (aka Bare Metal Backup)
  • Can be restored as a whole and powered on (like a snapshot) or
  • Can be used to selectively restore specific files.
  • Leverages data duplication to make backups efficient
  • VADP provides open set of APIs to 3rd party backup providers so probably supported by your current backup software

High Availability (HA)

  • Helps protect against hardware failures
  • vCenter used to configure, but is not required to operate – each host participates in a “monitoring relationship”
  • When a Host fails, the VMs will be migrated to the surviving Hosts and restarted.  The VMs will crash, but are often restarted with a minute or so.
  • Special software and drivers can also detect a VM failure.  If the OS crashes or other instability is detected, HA can restart the VM automatically.
  • By leveraging part of VMwares “Hyperic Product Suite”, HA can monitor specific services and applications even if the OS remains active.

Monitor ESXi Hosts

  • Configured by vCenter, but do not rely on it to monitor hosts
  • Each ESXi host participates in monitoring other hosts
  • If a host crashes, the VMs are distributed between surviving hosts
  • * The crashed VMs will need to restart, but are usually up within a minute or less.

Monitor VMs

  • Can also be used to monitor VMs using a special set of software and drivers. These talk to the ESXi host
  • Should this communication fail due to OS fault or other issue, HA can restart the VM automatically.
  • Highly configurable, so different criteria can be applied.

Monitor Applications

  • Leverages WMwares “Hyperic product suite”, can monitor applications and services.

Fault Tolerance (FT)

  • Used for applications that MUST NEVER FAIL, or can cause data corruption if they do
  • Perpetually mirrors specific VMs to another ESXi host
  • Used “active-passive” clustering that is completely transparent to the application
  • Once a failure occurs, the “passive” VM becomes the primary and a new secondary is created automatically.
  • Easy to configure
  • FA VMs are limited to 1 CPU in 5.x and up to 4 CPUs in 6.x depending on licensing.

vSphere Replication (VR)

  • Used for Data Center Replication (between data centers, different sites, etc.)
  • Can also be used to replicate data to a central location for data protection or recovery. (Remote locations – > Corporate office)
  • Can be restored at a “point in time” in case recent changes are corrupt.
  • Similar to R1Soft, you configure replication interval at remote site.
  • Can monitor replication to ensure it is working.

 

 

 

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