My job is to add another RAID1 along already installed RAID1 and there are few things I'd want to make sure of before starting anything as I'm still not sure of what might (or not) happen, because there is quite a lot of important data present on the existing raid.
Both of raids will be installed to the motherboards own raid controller and the new one I'm about to add is 3141SAS hotswap with 2x1TB HDD's in it. Already existing raid has operating system installed to it.
Is there something I should know of before doing anything and is it required to do changes to OS after installing the raid?
The only change that you will have to make to the OS after installing the RAID is partitioning and formatting the newly-created 1 TB volume.
What you need to be aware of is that you will have to attach the two drives to two of the chipset's SATA ports and interrupt the BIOS boot sequence at the point where it offers to reconfigure RAID. You will have to bind the two new drives into a single RAID volume.
If you have not done this three times before, and are not qualified to write a manual on it, do a complete image backup of all the other storage on the machine first. That way, if anything goes wrong you will be able to restore the machine to its original state and not lose all the software and data. You would be surprised how easily pressing the wrong button (figuratively) can wipe out stuff you don't think that you are touching. Be careful.
Yes I just made the raid today, I was roaming around bios while looking for raid settings and for my surprise, I did not find any. Not even after BIOS boot. So in the end most of my fears were for nothing as there was nothing done outside operating system.
Which also kind of let me down because now I know that the server will spend much more CPU power on the raid than I originally intented. Especially when this raid was created to hold first backups from the offices work PC's. (There will be masses of several hundreds of GB's forced on to server weekly)
I'm not sure what you mean with "ahead of the game", but yes the raid was produced in Disk Manager.
I made the backup queries so that they will try to run when people are on breaks or not at work yet, so that will reduce the network load at working hours. (The same server is used as file server)