My question is, do I need to perform some kind of re-leveling of music files from the maxed out 1st drive to the new 2nd empty drive?
I would say no at 90% capacity and just point iTunes to the newer drive, itunes will know the existing files are on the older drive and the newer files on the newer drive.
At 99.5% I would reduce it 90%, but iTunes doesn't make the migration that simple. I would recommend to always buy a larger capacity drive for the replacement and let itunes copy the files. If you also have video files on the old drive, you can probably move a few of those to get below the 90% target I like. Also at 99.5% I would assume iTunes has already added media to your internal drive, so you might review that too.
If you purchased a larger drive you could have easily migrate by pointing iTunes to the new drive and then consolidate the library, it's that simple, but with 2TB it will take several hours to do the copy. Keep in mind iTunes won't move or remove the old files. With your approach do point iTunes to the new drive, but don't consolidate the library as you will have two full drives...
The original 2 TB drive has really slowed down as it has reached its capacity and my notion is if I say move 10% 20% of its files to the new drive that it will regain its former speed.
Have you measured the performance drop? If there truly is one, and not another drive, I would probably say it's time replace the drive. I assume you do backups here, but the older the drive the more likely they are to fail.
Going forward, does the OS provide some intelligent resource storage leveling? (ie it will place files on one hard drive up to say a 90% capacity and then redirect all additional files to the next hard drive?)
Nope, you could do RAID0(a stripe) as noted or or JBOD, but using FW or USB drives on something that I consider reliability is more important then speed it's not worth it as a single point of failure kills the volume. Also if you do RAID0 you really want identical brand, model and capacity.
In addition, it is correct that I should also uncheck the "Copy files to itunes media folder when adding to library" and also uncheck the "Keep itunes media folder organized" selections?
Point iTunes to the new drive and leave both of those enabled so any new files you add go to the new drive and also to keep the new files organized. When sharing 2 drives, don't ask iTunes to "consolidate the library".
Before you do anything though, make sure you have all of this backed up. It's easy to make mistakes.
Jim
