Storage cutover time considerations for Copy-Free Transition

Storage Cutover Window

 For Copy-Free Transition, the storage cutover window starts from 'Export & Halt' operation and ends with the 'Import' operation. Storage cutover window contains the following three phases:

• Export & Halt - Automated by 7-Mode Transition Tool
• Cabling - Manual operation by the customer
• Import   - Automated by 7-Mode Transition Tool 

In most cases, the storage cutover time can be 3 through 8 hours. Cutover time includes the time taken by the tool to perform two automated operations - the export and halt operation and the import operation, as well as the time taken for manually cabling the disk shelves to the new controllers. The export and halt operation and the import operation together can be upto 2 hours.

Note: For scaled configurations, the export and halt operation and the import operation together can take more than 2 hours. 7-Mode Transition Tool detects such conditions and provides a warning.

Cabling of the disk shelves can take from 1 hour through 6 hours. This cutover time guidance does not include the time for the required preproduction testing and assumes an error-free transition without unexpected failures such as disk failure.
 

Recommendations

The following are the recommendations for reducing the storage cutover window for Copy-Free Transition:

• Make sure that in a Windows system where the 7-Mode Transition Tool is installed, the 7-Mode controllers and target cluster are on the same local network. This will reduce the network latency when 7-Mode Transition Tool is communicating with the 7-Mode controllers and the target cluster.
• Download and read the Copy-Free Transition Cabling Guide and fill the Copy-Free Transition Cabling Worksheet provided in the guide.
• Download the Config Advisor and make yourself familiar with it. NetApp recommends you to run the Config Advisor on 7-Mode controllers to detect any issues. After the 7-Mode disk shelves are connected to target cluster nodes, it is recommended to run the Config Advisor on the cluster to detect any cabling issues.
• Days ahead of the cutover window, apply the SVM configurations (Apply SVM Config operation) and make the necessary changes to the target SVM configurations.
• Verify the applied SVM configurations and test connectivity with external servers like DNS, NIS, and AD.
• If 7-Mode controllers contain iSCSI or FC LUNs, perform the required Zoning and any host-side remediation steps. For more information, see the SAN Host Transition and Remediation Guide
• Hours ahead of the cutover window, run the cutover readiness operation (Check Readiness operation) to make sure that there are no blockers for the transition.
   

Configuration Sample

In the lab tests, the following are the example configurations and the time taken for each of the 'Export & Halt' and 'Import' operations:

Notes: 

• The above are the combined number of configurations across both 7-Mode controllers in the source HA pair. 
• These timings might vary based on the network latency and load on the 7-Mode controllers and cluster.
• Is it observed that collecting quota rules from 7-Mode and applying those quota rules on target SVM takes significant amount of time if there are thousands of quota rules. The time increase in the 'Import' operation time for the above second example can be contributed to the increase in quota rules between first and second configuration examples.
   

Acknowledge the blocking error produced by the 7-Mode Transition Tool:

To acknowledge the blocking error produced by the 7-Mode Transition Tool and convert it into a warning, run the following command on the host where 7MTT is installed, and then re-run the precheck operation:

transition cft ignorableerrors add -p <project-name> -c ignore-configuration-limits-check