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# Make configuration changes safely

Certain configuration tasks that are performed on a storage system may not be not immediately processed, but instead are kept in a job list for review and submission in batches.

## About this task

Before making configuration changes, you must thoroughly understand your storage system configuration. The following guidelines establish safe disciplines as you begin any change that can impact stored data:

Ensure that it is viable to make configuration changes to the current configuration.

Before creating volumes, check for free hard drive space. New storage volumes are created first on hard drives that have no prior allocations, causing these disks to be committed to that emulation type.

No configuration change is activated in the storage system until you commit the action.

Some classes of change operations may or may not impact current I/O. When possible, before you commit any action, stop I/O activity on the volumes to be altered during a configuration change session.

Ensure that all your critical data is preserved and safe when creating new or changing volume configurations. Do not store data on any volume that is not mirrored.

After committing a mapping operation, you must update the volume mapping information within the host system environment. Attempting host activity with a volume after it has been removed or altered, but before you have updated the host's volume information, can cause host errors.

If I/O activity on an affected volume occurs before or during a commit action, the commit action might fail. Heavy I/O activity on unaffected volumes impacts how long it takes to commit changes.

Contact Customer Service for assistance in reverting to your previous configuration should there be unforeseen problems with the new configuration.