High Availability and Disaster Recovery using

Virtualisation

info@techarchsolutions.com

www.techarchsolutions.com

Definitions

• HA – ability to proactively avoid some types of disasters before they occur

• DR – ability to quickly recover data and restart business operations in the event of a disaster

Traditional HA solutions - Clustering

• Purpose– High Availability– Scalability/Load Balancing– Manageability

• Types– Active/Active– Active/Passive– Cold Failover– Hot Failover

Traditional HA solutions - Clustering

• Benefits– Reduced probability of disaster occurrence– Reduced planned downtime windows and costs– Improved operational efficiencies

• Disadvantages– Expensive IT investment– Active / Passive clusters waste hardware– Complex implementation

Current DR solutions• Media-based backup/restore

– Good: Familiar, cheap

– Bad: slow, high cost of downtime

• Cold Standby– Good: server availability

– Bad: wasted hardware

• Hot Standby– Good: quick turnaround time, multitasking

– Bad: expensive

What is Virtualisation?

• Multiple virtual systems residing on a physical server.

• Provides a layer of abstraction between the hardware and software that runs on it.

Virtualisation as an Option• Disadvantages

– Not recommended for servers that are heavily utilised– Not recommended for applications/servers requiring specific

hardware requirements– If designed badly, single point of failure

• Advantages– Greater solution ROI– Savings on hardware and rack space– Ease of management– Efficiency in deployment of VMs– Zero-downtime hardware maintenance– Higher SLA and DR at a lower cost

Clustering for Higher Availability in a Virtual Infrastructure

• Cluster Virtual Machines for High Availability

• Cluster host servers for High Availability• Application Clustering• Virtual Infrastructure can be a replacement

for clusters where clustering for H/W failure only

Virtual Machine HA solutions• VMs can be run from

any server in a pool

• VMs can be dynamically moved between servers

SAN – same LUN presented to all systems

VMotion

Redundant data paths to Viirtual Machines stored on SAN

Dedicated network for VMotion migrations

Teamed network interfaces available to Virtual Machines providing network redundancy

Servers are able to share the same VMFS2 filesystem on the SAN

Virtual Center Console managing ESX Server

Farm

Disk redundancy provided by SAN

Virtual Machine HA solutions• VMs from a

failed server can be brought back on-line in remaining server pool quickly (within/across DCs)

Clustering with Virtual Machines

• Cluster between physical and virtual machines

• Cluster-in-a-box

• VM Clustering between 2 Host Servers

Physical-to-Virtual Clustering• Physical

machine clustered with a Virtual Machine

• Shared storage required

PM VM

PNet FNet

HB

Cluster in a Box• One VM is

primary and second is backup

• Quorum on shared storage PNet

HB

FNet

VM1 VM2

ESX Server

VM clustering between two servers

• VM on one host is primary, VM on second host is backup

• Shared storage required

VM2VM1

HB

FNet

ESX 2ESX 1

PNet

Virtual DR solutions• VMotion between DCs

• SAN mirroring between DCs

• Snapshot and copy between DCs

• Snapshot to tape or file server

• Physical to virtual DR

Virtualisation Vendors• Xen

• Solaris Zoning

• Microsoft Virtual Server 2005

• VMware ESX

Migration Tools for Virtualisation• Microsoft VSMT

• Leostream P>V direct

• VMware P2V Assistant

• Platespin PowerConvert

PlateSpin PowerConvert

PlateSpin PowerConvert Solutions

• Consolidation• Recovery• Test lab automation• Business Service

Provisioning• Hardware migrations• Data Centre Moves or

Centralisation

Future of Virtual Infrastructure• Host server clustering – ability to automatically bring up

VMs on secondary server in the event of failure

• Integration of the system failure detection card into the ESX layer

• Self managing Data Centres

• Application virtualisation (Softgrid Softricity)

QUESTIONS

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