Restoring an existing RAID/LVM data array

[PeterHobson]

Thanks to your excellent guide I have successfully set up my media server using an old mobo/cpu and other spare parts plus four new 2TB hard drives. I have everything running well now but want I want to do next is set up the storage pool using software Raid 5 and then use LVM on top of that. My aim is to be able to set up folders so I have protection against disk failure and can expand as required without being constrained by physical disk capacity. I have a separate disk for my OS which is not configured as Raid but was installed with the LVM option checked.

I understand that I can set up the data Raid array with mdadm and run LVM on top of that. However what I’m not sure about is: once that is all set up, if I ever have to reinstall the OS for any reason will I lose the data on the disks running Raid and LVM? All the documentation I have found seems to assume any Raid or LVM configuration is to be set up on clean disks or that existing data is not needed and would be lost. Is this the only option or can an existing Raid and/or LVM configuration somehow be ‘re-mounted’ under a new OS?

I will be backing up of course so it’s not the end of the world if I can’t, but restoring large amounts of data can be slow and as I’m still very much a Linux beginner I do anticipate have to re-build the OS a few times. So if I can leave the data intact it would make life much easier!