VMware Fault Tolerance provides zero-downtime, zero-data-loss continuous availability for any application, without the cost or complexity of traditional solutions.

VMware Fault Tolerance is a component of VMware vSphere that provides continuous availability to applications, preventing downtime and data loss in the event of server failures. VMware Fault Tolerance, built using VMware vLockstep technology, provides operational continuity and high levels of uptime in VMware vSphere environments, with simplicity and at a low cost.

How Does VMware Fault Tolerance Work?

VMware Fault Tolerance, when enabled for a virtual machine, creates a live shadow instance of the primary, running on another physical server.

The two instances are kept in virtual lockstep with each other using VMware vLockstep technology, which logs non-deterministic event execution by the primary and transmits them over a Gigabit Ethernet network to be replayed by the secondary virtual machine.

The two virtual machines play the exact same set of events, because they get the exact same set of inputs at any given time.

The two virtual machines access a common disk and appear as a single entity, with a single IP address and a single MAC address to other applications. Only the primary is allowed to perform writes.

The two virtual machines constantly heartbeat against each other and if either virtual machine instance loses the heartbeat, the other takes over immediately. The heartbeats are very frequent, with millisecond intervals, making the failover instantaneous with no loss of data or state.

VMware Fault Tolerance requires a dedicated network connection, separate from the VMware VMotion network, between the two physical servers.

How is VMware Fault Tolerance Used in the Enterprise?

VMware Fault Tolerance is used in the enterprise to prevent application disruption due to hardware failures. Downtime associated with mission-critical enterprise applications can be very expensive and disruptive to businesses. Traditional solutions that address this problem through hardware redundancy or clustering are complex and expensive. VMware HA addresses server failures by automatically restarting virtual machines on alternate servers. VMware Fault Tolerance takes high availability to the next level, completely eliminating downtime due to hardware failures with simplicity, at a low cost and across all applications, regardless of operating system.

With VMware Fault Tolerance, IT organizations can,

  • Eliminate even the smallest of disruptions due to server hardware failures. 
  • Provide continuous availability to any critical application. 
  • Deliver uninterrupted service with simplicity and low cost. 

Key Features:

  • VMware Fault Tolerance automatically detects server failures and triggers instantaneous, seamless stateful failover resulting in zero downtime, zero-data-loss continuous availability.
  • VMware Fault Tolerance automatically triggers the creation of a new secondary virtual machine after failover, to ensure continuous protection to the application.
  • VMware Fault Tolerance works with all types of shared storage, including Fibre Channel, NAS or iSCSI.
  • VMware Fault Tolerance works with all operating systems supported with VMware ESXi.
  • VMware Fault Tolerance works with existing VMware DRS and VMware HA clusters and only an additional dedicated gigabit Ethernet network.