Susanne58,   To start let me point you to the manual, as a lot of what I am going to say you can find steps for in there.   We are also going to need additional details in order to accurately assist. Now since the T610 doesn't appear to support cabled hard drives, you should find the drives installed on the front of the server, under the front bezel. You can find steps to remove the bezel on page 79-80.  Once the bezel is removed, how many drives do you see installed, and are there any displaying amber lights, if so is it flashing amber and green?   My next question is, can this server be shut down or is it in use/production currently? The reason I ask is the next steps we will need to take is to reboot to the raid controller, in order to verify the actual status of the physical disks, as well as what Raid level the Virtual Disk is.    This is important because if the virtual disk, hypothetically, is a raid 1 then it is redundant and the failed drive can be replaced. Now in a different scenario, if the virtual disk is a Raid 0, then there is no redundancy and you can't just replace the drive without backing it up.   In order to give you accurate advice we will need to know the hardware installed, so would you please private message me the svc tag?   Let me know and we can go from there.    
I have been tasked to install a second hard drive in an older T610 desktop style server running ubuntu. I am not a computer tech. I can find info for mounting etc from the linux side, but I do not see where physically the drive would be installed inside the server. it has an empty bay underneath a DVD drive, and I understand an adapter can be found, or is there another location? I cannot 'see' where the currently installed hard drive is. I also dont know if I need any wiring/connectors. all I can find is videos for a blade server, does anyone know one for the tower version? and yes, I probably should not be messing with this, but our university does not have ANY linux support techs and the current hard drive is starting to fail.
second hard drive in Ubuntu poweredge T610