I had a total disk failure, no recent backup, lost everything since September.

Oh well nothing I can do about it, life goes on.

My replacement drive arrived and then I thought about installing RAID 1 so I ordered a second drive, the same exact model.

It does not support the TLER(?) used by hardware RAID, so I will use Software RAID.

The day after I shipped the drive back to WD for replacement I rebuilt my system with an old IDE 17GB drive.

Can I build the RAID 1 on the 2 new disks in a running system?

They are WD3200AAKS FWIW 320GB, 512byte sectors (4K would have been better)

Can I just install mdadm and build the system up or must I use alt install?
(Or is it just really really wise to just do it that way?

Tom