Use IBM AIX snapshot method to backup db

Hello, Before any major implementation or db upgrade, in order to have an consistent db backup, we use to take an offline database backup at OS level by doing an ARCHIVE with IBM Tivoli Storage Manager. As the db get expansion and takes more than 2 hours to finish an offline backp now, in order to minimize the db downtime, we are planning to use 'IBM AIX Snapshot' method to take a db backup. I think that I need to do the following steps but I am not sure :
1. Have snapshot disks ready
2. Shutdown db
3. Activate AIX snapshot (it takes no more that 2 minutes)