"Can I just switch physically the primary disk with the secondary, so the new disk will be the primary disk?" There is no primary disk  on lsi based controllers. The is a preferred disk the controller writes to first, it could be either disks of a raid 1 pair, chosen by the controller upon installation.  Can I just switch physically the primary disk with the secondary, so the new disk will be the primary disk? If you were to "switch" the disks, it is a bit involved, no less there is absolutely nothing to gain, the data is the same on both disks. "Does this controller read from the primary disk or from both?" There are raid controller which read from both drives in raid1, LSI based do not, the controller will read from the disk which is preferred by the controller, unless the is an issue, then it will read from the other disk in the array.  
Hi! I have a dell server running in raid1 with controller SAS 6/IR. I recently replaced one of the disks for a new one. (the secondary disk). They are now with status ok. Can I just switch physically the primary disk with the secondary, so the new disk will be the primary disk? Will I have any advantage with this? For example, when I want to replace the old disk by a new one also... Does this controller read from the primary disk or from both? Thanks
Switch disks on a SAS 6/iR controller RAID1