[CentOS] Identifying physical disks

I am sure this is really simple.

I have a setup of 2 disks (sda, sdb) which are outwardly identical, and 
are mirrors of each other. Together they form 3 raid1 devices. Both 
disks can boot.

Now sda has bad sectors, and I should replace it. But which one of the 
physical disks is sda??

The machine boots fine from either one of the disks, (and the booting 
disk of course is always called sda).

In the messages log I see entries like this:

Apr 29 02:21:07 a134-224 kernel: ata2: SATA link up 3.0 Gbps (SStatus 
123 SControl 300)

By noticing which SATA link (ata1, ata2) is up and which is down, I can 
find out which physical disk is connected to ata1 and which to ata2.

If both disks are connected, will the hd in ata1 become sda, and the hd 
in ata2 become sdb??

- Jussi