software RAID replacing hard disk

[wbens]

Hello Forum:

I am learning about software RAID. I have setup RAD1 on one of my servers at home. This is what I have from the /procs/mdstat file:

cat /proc/mdstat
Personalities : [raid1]
md3 : active raid1 hdd3[1] hdb3[0]
68364480 blocks [2/2] [UU]

md2 : active raid1 hdd2[1] hdb2[0]
78132032 blocks [2/2] [UU]

md1 : active raid1 hdd1[1] hdb1[0]
97667072 blocks [2/2] [UU]

md0 : active raid1 sdb1[1] sda1[0]
241665664 blocks [2/2] [UU]

unused devices: <none>

Now I need to fail one of the drives, and replace it. For example, let us say I purposely fail the hdd drive. Ok, that is not a problem. However, the problem for me is when I have to physically remove it from the server itself. I have two hard drives making up the software RAID1. How do I know which one of the two to remove?

[Lazydog]

Do you know which drive is which in your system? Looks like you only have 4 drives so you should know which is which.

[wbens]

Hello Lazydog:

Thanks for your reply.

Actually, I am just concerned about the md1, md2, and md3 arrays. I should had not posted the md0 array. Please disregard that one.

[Lazydog]

Well if you lose a disk all of those raids will be affected. Looking at the disc connections should tell you which disk is which.

[Rubberman]

Disconnect one of the candidate drives and see which one has gone off-line? If you run the disc utility, it will be pretty obvious which one is off.