DR Design Guides
Appendix A - Advanced Failover Modes

Appendix A  - Advanced Failover Modes

Cached config advanced mode

In some cases customers can not pre-sync configuration data from one cluster to the DR site, as this exposes data at the DR location.   This requirement means, all configuration data must be cached on the Eyeglass appliance versus pre-synced to the DR cluster.

Eyeglass always has a database of changes but it’s not used for failover operations as this information can be stale in planned failovers.   As of release 1.6 and later a failover mode switches Eyeglass to sync configuration data to files that are used in all failover modes controlled and uncontrolled.

The process now looks like this:

  1. Sync every 5 minutes, get configuration information difference changes and update local files on Eyeglass appliance.
  2. Controlled AND uncontrolled failover reads from cache files only, and never communicates with the source cluster to create shares, exports, quotas during the failover process on the target DR cluster.
  3. For controlled failover this means that potential stale data is used to failover in this scenario.

How to enable cached config advanced mode

  1. Ssh to Eyeglass as admin.
  2. igls adv failovermode set --readfromfile=true.
  3. Done.
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