Availability Best Practices in VMware vSphere

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Agenda     

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VMware Solutions and Business Continuity – Availability Fault Domain Manager (FDM) Fault Tolerance (FT) Overview Additional Resources Q&A

VMware Solutions and Business Continuity VMware Offers Protection at Every Level

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VMware HA VMware HA:

• Provides automatic restart of virtual machines in case of physical host failures • No need for passive standby hardware and dedicated administrators • Support for virtual machine failures monitoring it, no additional software required VMware HA has several advantages over traditional failover solutions, including:

• Minimal setup • Reduced complexity • Reduced hardware cost and setup • Increased application availability without the expense of additional failover hosts • VMware DRS and vMotion integration

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VMware HA in Action

LUN 6 LUN 5

LUN 4 LUN 3 LUN 2

LUN 1

virtual machine A

virtual machine B

virtual machine A

virtual machine C

virtual machine E

virtual machine B

virtual machine D

virtual machine F

host

host

host

vCenter Server

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Architecture of a VMware HA Cluster

vCenter Server

vCenter Server agent

host

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VMware HA agent

host

vCenter Server agent

vCenter Server agent

VMware HA agent

VMware HA agent

host

Enabling VMware HA

Enable VMware HA by creating a cluster or modifying a DRS cluster.

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Configuring VMware HA Settings Disable Host Monitoring when performing maintenance activities on the host.

Admission control helps ensure sufficient resources to provide high availability.

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Admission Control Policy Choices

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Policy

Description

Recommended use

No. of host failures

Reserves enough resources to tolerate specified number of host failures

When virtual machines have similar CPU and memory reservations

% of resource reserved

Reserves specified percentage of total capacity

When virtual machines have highly variable CPU and memory reservations

Specific failover host

Dedicates a host exclusively for failover service

To accommodate organizational policies that dictate the use of a passive failover host

Configuring Virtual Machine Options Configure options at the cluster level or per virtual machine.

VM restart priority determines relative order in which virtual machines are restarted after a host failure. Host Isolation response determines what happens when a host loses the management (or service console) network but continues running.

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Configuring Virtual Machine Monitoring

Restart a virtual machine if its VMware Tools Heartbeats are not received.

Determine how quickly failures are detected.

Set monitoring sensitivity for individual virtual machines.

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Configuring Virtual Machine Monitoring

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Fault Domain Manager/vSphere HA 5.0

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FDM Architecture:

 FDM uses a FDM agent: • The agent on one host is the master and on all other hosts slaves • Uses both the mgmt. network and storage devices for communication • It also introduces IPv6 support • New configuration mechanism reduces the cluster configuration time to ~1 minute • When HA is enabled, all FDM agents participate in an election to choose the master

 Master is elected when: • vSphere HA is enabled • A master host fails • A management network partition occurs

 Heartbeat Datastore: • A new feature of FDM is its ability to use Heartbeat Datastores • Datastores will be used to communicate only when the management network is lost

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FDM Master and Slave Views:

Master View

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Slave View

Heartbeat Datastores  We can select datastore only when hosts are in the cluster.

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•

Using the datastore as a method of communication allows a master to:

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Monitor availability of slave hosts and the VMs running on them

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Determine whether a host has become Network Isolated rather than Network Partitioned

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Coordinate with other masters, who will coordinate VM ownership thru datastore communication

HA States

 A new host property to report the HA state of a host  Possible States are: • N/A (HA not configured) • Election (Master election in progress) • Master (Can be more than one) • Connected (to master over network) • Network partitioned • Network isolated • Dead • Agent unreachable • Initialization error • Unconfig error

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Fault Tolerance

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What Is FT? FT: • Provides a higher level of business continuity than VMware HA • Provides zero downtime and zero data loss for applications

FT can be used for: • Any application that needs to be available at all times • Custom applications that have no other way of doing clustering • Cases where high availability might be provided through Microsoft Cluster Service but MSCS is too complicated to configure and maintain

FT can be used with DRS: • Fault-tolerant virtual machines benefit from better initial placement and are included in the cluster’s load-balancing calculations

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VMware Fault Tolerance (FT)

PRIMARY

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SECONDARY

Additional Resources  VMware Availability Guide: http://www.vmware.com/pdf/vsphere4/r41/vsp_41_availability.pdf http://pubs.vmware.com/vsphere-50/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenterserver-50-availability-guide.pdf

 VMware Fault Tolerance http://www.vmware.com/products/fault-tolerance/

 Documentation and Whitepapers VMware Fault Tolerance Recommendations and Considerations on VMware vSphere 4: http://www.vmware.com/resources/techresources/10040 VMware vSphere 4 Fault Tolerance: Architecture and Performance: http://www.vmware.com/resources/techresources/10058

 Forum http://communities.vmware.com/community/vmtn/vsphere/availability?view=discussions

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