How to create RAID1 without data loss?

Question

Debian

Good afternoon!
There is a server on Ubuntu Server 16.04.
The OS is installed on an SSD. Soon I will install a second SSD of an identical model / volume there. Please tell me how to assemble these RAID1 SSDs without losing the installed system?

Answer 1

Depends on what means you are going to do RAID.
In the case of mdadm - for example .
There is one point - any work with disks, partitions, raid is a potentially dangerous operation that can destroy your data.
And only one remedy helps against data loss - backup!.

Answer 2

If the motherboard supports hard raid, or there is a controller, it's better to make one, I have a biased attitude towards soft ones. We make an image of the system -> go to the controller configurator -> create an array - roll the image. It usually goes without problems. If the ssd is pci-e, then it is usually possible to dig into the configs of the ssd itself and see that, for example, a terabyte consists of four 256 GB disks combined into a zero array (personal experience) and it is possible to create even a 10 array.