switched startup drive - safe to delete old startup partition?

[daveh0]

I recently put a 2nd drive in my 2011 iMac. I had been running OSX on the single HDD. But now with a faster SDD, I downloaded the High Sierra installer to the HDD and ran it specifying to install to the SSD. When the computer restarted, I held down the Option key and specified to start from the SSD. Much to my surprise, when it started from the freshly installed version, I was still able to log in with my user from the previous install on the HDD. I was sure all that would not be accessible by the new install. Now that I know the OS running from the SSD works, I'd like to delete and repurpose the partition from the HDD that contains the old OS. Will this cause me to lose the ability to retain my user account and settings? Should I do this anyway? I was pretty much prepared for a clean install and like I said, was very surprised to find everything still in place as if no changes were made (other than the increase in speed having the OS on the SSD)....

And I am certain that it's running from the SSD

 

[Fishrrman]

I'd keep a booting copy of the OS on BOTH drives.

Then... if one drive fails... you can IMMEDIATELY boot to the finder and run from the other one.

Two bootable copies of the Mac OS (on different drives, of course) are ALWAYS better than having "just one".

 

[daveh0]

I'd keep a booting copy of the OS on BOTH drives.

Then... if one drive fails... you can IMMEDIATELY boot to the finder and run from the other one.

Two bootable copies of the Mac OS (on different drives, of course) are ALWAYS better than having "just one".

You couldn't be more right!!

Right now, i have that partition set to around 500Gb. With minimal apps installed, I'm guessing I'd be safe reducing it by about half (or more)? When I change the size in Disk Util, will it automatically allocate the remaining space to the the only other partition on that drive or will I have to somehow specifically add it to it?

Also, I have all my data on this "only other partition" cloned/backed-up of course, but of-course (again), i'd like to avoid having to restore it. With that said, how risky (to other partitions on the same disk) of an operation is it to change the space allocated to a given partition...in this case, the 500GB partition containing the now-backup OS? If there's anything other than an ultra-low probability of losing data in the process, I may hold off on the resizing until workload slows =)

 

[Fishrrman]

Reduce the size of the old boot partition to whatever you like.
Depending upon "how much" is on it, you might even shrink it down to around 30gb (with nothing more than the OS, apps, and a basic account on it).

And once you've done this, do "a test boot" from it, just to be sure it works.