I'm looking for a way to create the RAID 1 array without losing my data on CentOS. Here's my situation: I've got a web server running on CentOS. There is one VG partition with few LV volumes. I bought a second HDD (the same model and size as the first one) and I want to create the RAID 1 configuration. I can't just shut down this server for more than an hour because my clients will be disappointed. I need to do this as quickly as possible with minimal risk of data loss.