I have successfully implemented a RAID1 software raid configuration with mdadm. I actually prefer Software Raid over hardware raid, for reasons I am not listing at the moment, as it falls out of the scope of the whole situation I am in.

The problem is, I am wanting to create a RAID5. I have the extra hard drive ready. The hardware really isn't the issue, its the data portablity. I know that if one drive failes, I can just hot swap it (i have hot swap bays). The problem is, what if the OS fails? What if I decide I need to reinstall the OS due to OS related issues?

Do I lose that RAID5 because its sofware? Do the disks remain in the same state, and when the reinstall of the OS I can just add them to a mdadm array or does it reformat the array? (the disks in the RAID would not be formatted or touched in the reinstall .. ) If so, that would defeat the point, because I would literally have to take the array .. back it up .. and then put it back on the array.

So my overall question is:

By an OS reinstall, can I readd and preserve a software raid without losing any data?

PS - here is how my disks are setup:

1 x 20GB IDE (OS)
3 x 250GB SATA II hdd (Raid5)

Thanks in advanced.