My ISIS 5500 is a 16 x 1TB storage.

I've been looking for 1TB AVID drives to get to replace out a failing one, but I haven't been able to find them anywhere. Instead I got some 2TB WD drives that were supposedly taken out of a known good chassis.However, the bad drive just failed a few days ago and I tried to install one of the 2TB drives. After I cleared the foreign config I got "Invalide spare drive slot" I guess since the size of the new drive doesn't match up to the rest of the drives.  

Is there anything I can do to get a 2TB drive to work in the existing RAID with my ISIS running 1TB drives? 

Unfortunately, the drive must contain the Avid firmware in order for the ISIS system to accept it.

You will need to find an Avid drive.

Thank you, Dom.

It is supposedly an Avid drive with Avid firmware. The only difference is it's a 2 TB drive instead of 1 TB. SHouldn't the system still recognize it and just use 1 TB of it? 

Correct. A larger drive, 2TB in this case, is a valid replacement for the smaller 1TB drive.

Try rebooting the server chassis.

Hi,

If the drive wasn't empty and you had to clear foreign config the raid controller does not add the drive automatically to the raid set as a global hot spare. It has to be set to a global hot spare manually.

Can you confirm in the megaraid utility if the 2TB drive is considered to be a global hot spare? 

What version of ISIS are you running?

Thank you, Dom, for your suggestion. I rebooted the chassis and the message changed from "invalid spare drive slot" to "Missing spare drive". 

Still trying to figure out where to go from here. 

Pull the drive out. Mount it on a Windows PC and "clean" it. 
 https://www.seagate.com/support/kb/how-to-diskpart-eraseclean-a-drive-through-the-command-prompt-005929en/

I took your advice, Jeroen and it worked! Here's what happened in a nut shell: 

I had to get the correct MegaRAID Storage Manager installed but the GUI wouldn't work. So my senior technician had to access it through command prompt using the Storage Command Line Tool (StorCLI). From there we could see that the spare drive was assigned as Unconfigured Good not as a Global Hot Spare.

Using a simple StorCLI command (easy to find in the StorCLI reference manual from LSI) we had the drive assigned as a Global Hot Spare and the ISIS accepted it as the hot spare!

So thanks a lot for your note!

As a warning to anyone out there -- in resolving this, I did run into an issue with Java.exe. The MegaRAID Storage Manager required Java which we then installed on the System Director.

We later had serious issues using the ISIS on any computer and in any project. We found java.exe leaking memory, causing the ISIS to become basically useless.

By ending the process -- java.exe -- and rebooting, we handled all the issues. But watch out if you see I/O errors from all your disks, a lot of error code 112 when you know you have enough space, and your physical memory maxed out above 99% -- you probably have an out of control program leaking memory.