Installing El Capitan


I have an iMac circa 2011 running 10.6.8 and want to install El Capitan. My question is that I have a couple of external drives with 10.6.8 compatible software that I still use. If I clone my existing HD to the external, install El Capitan and later wish to reboot from the external to use the software will El Capitan let me?
Depends on the exact model and what type of connection your external has. There are some iMac’s that can boot via external if it is Firewire only, some that can boot USB. The external needs to be set up as a bootable 10.6 drive not just a copy.
I have the folowing:
Model Name: iMac
Model Identifier: iMac12,2
Processor Name: Intel Core i5
Processor Speed: 3.1 GHz
with two 1tb firewire externals that I regularly back up to via Carbon Copy Cloner. I can boot from either of these drives with no problem and be perfectly functional.
My question is will El Capitan allow me to do this?
I don't see any problem with running those apps in El Capitan. Are your external drives bootable? If so, you can run the apps from the ext HD but El Capitan should be able to run them, as well. It's not like a PPC app trying run on Intel processors.
You definitely should. I do not have Carbon Copy Cloner--I use SuperDuper!--but I believe both make "bootable clones." I only used it because "Back in the Day," Time Machine did not make "bootable clones."

I did the same thing you want to do. I was on your system, I cloned it, I then tried El Capitan. I was then able to boot--again--from my clone and, if I wanted to--cloned to my El Capitan HD if I did not "wike it" for whatever reason.

Since you can boot from clones made by CCC now, you should have no problem doing that! Heck, there are Techies with Huge-Ass HDs that partition them so they can put a new OS on one partition to test it. They do not like it? They go to the other partition!