Virtualisation 101 – SRM

This is the first in a short series of high level articles intended to explain how some of VMware’s products and features work, to help anyone that needs to get up to speed quickly on a particular topic.

What Is It?

Site Recovery Manager is a VMware product that enables protection of a virtual infrastructure at a site level.  Once configured, SRM can orchestrate the recovery of a failure of the primary site, bringing virtual servers online quickly, and in a predetermined order, at the recovery site.

What Do I Need to Deploy It?

  • A compatible SAN – The SRM application uses a vendor-specific Site Recovery Agent (SRA) to talk to the SAN.  Check the SRM Storage Compatibility Matrix to ensure your SAN is on the list (link below).
  • Two SANs  –  Replication of data is done by the SANs, not by SRM, so the Recovery Site requires a SAN of the same type as the Protected Site SAN  that has sufficient spare capacity to host a mirror copy of the Protected Site’s data.  You can decide on a per-LUN level whether to replicate or not.  But remember you will need more storage.
  • SAN Replication  –  Terminology will vary between vendors, but basically a Master/Slave setup is required between the SANs, with all changes on the Protected SAN copied over — as close to realtime as possible – to the Recovery SAN.  This means you’ll need a fast link between sites and to pay for SAN licensing to enable mirroring between SANs.
  • Good relations with your SAN engineers  –  the SRA requires an admin login to the SAN in order to interrogate it and initiate failovers.
  • Recovery Site resources  –  there needs to be ESX or ESXi servers at the Recovery Site with enough resources to run your protected servers.  The Recovery site also requires its own vCenter and SRM server, linked to those at the Protected Site, along with any supporting servers such as Active Directory and DNS.

How Much Does It Cost?

The core SRM product licensed in units covering 25 managed servers, with a list price of US $11,250 per 25 VMs. 

Other things to consider when budgeting for SRM:

  • Remember the prerequisites such as SAN replication licensing;
  • Extra Storage;
  • Adequate WAN links for SAN replication;
  • Provisioning ESX resources at the Recovery Site;  
  • Windows licenses for two vCenter servers and two SRM servers. 
  • The Requirement for Two vCenter servers and two SRM servers 
  • Larger scale deployments should also consider storing the SRM database externally.

Where Do I Go From Here?

SRM Storage Compatibility Matrix:

VMware SRM Docs page:

Administating SRM:, Mike Laverick’s eBook is essential reading before deploying SRM; it costs less than £7 and all proceeds go to Unicef, you can get a hard copy too.

VMware Communities page for SRM:, seriously folks I cannot state how useful this resourse is in your first steps to getting to grip with the product.  it should also be your fisrt stop when troubleshooting.

The next step in this series is a 102 post on how to setup working SRM evironment.

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