Yosemite on external SSD. Keep it that way or..?

[Racineur]

Hello, after much much hesitation, I think I can let go of Mountain Lion on my iMac late 2012, 3,2 i5, 1T FD, 8 Ram. I did this: I bought a 250 g external SSD and installed Yosemite 10.4.4 on it. I can now booth my iMac with the SSD. I am very pleased and happy with what I see and what I feel in Yosemite. A little faster than ML and no beachball from hell until now. I'm a bit restrained with what I can do since I can't install many apps on a small 250 g, but I can manage with Safari, Mail and Pages for now. Can't stand Photos though so I reverted to iPhoto. My question: it's been a clean install on the external SSD, what kind of installation would it be if I uppgraded from Mountain Lion 10.8.5 to Yosemite 10.10.4 from the App Store? A clean install? I read so many negative posts on Yosemite, I wonder if the kind of installation has some importance here? I have complete backups with Time Machine of my system. Lastly, will I lose for good ML? The ML installer on the invisible partition too? For whatever reason, could I use Time Machine to go back to ML? Thanks mucho for help and support.

 

[Taz Mangus]

Hello, after much much hesitation, I think I can let go of Mountain Lion on my iMac late 2012, 3,2 i5, 1T FD, 8 Ram. I did this: I bought a 250 g external SSD and installed Yosemite 10.4.4 on it. I can now booth my iMac with the SSD. I am very pleased and happy with what I see and what I feel in Yosemite. A little faster than ML and no beachball from hell until now. I'm a bit restrained with what I can do since I can't install many apps on a small 250 g, but I can manage with Safari, Mail and Pages for now. Can't stand Photos though so I reverted to iPhoto. My question: it's been a clean install on the external SSD, what kind of installation would it be if I uppgraded from Mountain Lion 10.8.5 to Yosemite 10.10.4 from the App Store? A clean install? I read so many negative posts on Yosemite, I wonder if the kind of installation has some importance here? I have complete backups with Time Machine of my system. Lastly, will I lose for good ML? The ML installer on the invisible partition too? For whatever reason, could I use Time Machine to go back to ML? Thanks mucho for help and support.

If you installed on top of 10.8.5 it would not be a clean install. Yosemite would replace the necessary system files on your 10.8.5 install. In other words, the Yosemite installer would install only what is required to be able to run 10.10.4. All your user account data will not be touched. One thing you could do, is use a program like Carbon Copy Cloner and copy your 10.8.5 install to your external hard drive. This will create an exact copy of your 10.8.5 install to your external hard drive. Then do a clean install of 10.10.4 onto your internal hard drive. Finally, setup 10.10.4 on your internal hard drive and use migration assistant to bring over your user data from the the 10.8.5 on the external hard drive. The reason I bring this up is because you mentioned that you are getting a lot of beachballing with 10.8.5 and there could be a possibility that installing on top of 10.8.5 will not solve that due to something already installed on your 10.8.5. Just a thought.

 

[Fishrrman]

As the poster above mentioned, by creating an external bootable clone of your 10.8.5 OS, and by just keeping it around for a while after you have made the transition to Yosemite on the internal drive, you will have some "insurance"...

 

[Racineur]

[QUOTE="Taz Mangus, The reason I bring this up is because you mentioned that you are getting a lot of beachballing with 10.8.5 and there could be a possibility that installing on top of 10.8.5 will not solve that due to something already installed on your 10.8.5. Just a thought.[/QUOTE]

Sorry if my words were misleading. I have no beachballs with ML. Actually, it's so stable, it's freaky. No nothing but pure stability. And no beachballs with Yosemite. In understand what you're suggesting to do with Carbon Copy Cloner. Excuse my lack of knowledge but what is the benefit of using Carbon Copy Cloner over my Time Machine backups? Is there something I should know about the Fusion Drive before having it erased in the process? I was told that the OS (Mountain Lion in that case) is installed on the SSD portion of the Fusion Drive. Will Yosemi be installed too on the SSD portion of the FD? Lastly, what about ML? Gone for always? I know, many questions, but it would be the firts time I do all this by myself. Don't wanna mess with the stability I'm used too.

 

[Weaselboy]

Excuse my lack of knowledge but what is the benefit of using Carbon Copy Cloner over my Time Machine backups?

For your purposes just to keep the old ML system around in case you want to go back to it, Time Machine will work fine and there is no reason to use CCC. The reason many like CCC it a CCC clone can be booted to and actually operate the computer from the external cloned drive. TM does not do that, as it requires to backup to be restored to the operating drive for real usage. For you purposes, just run a TM backup and set that disk aside if you want.

You could actually just keep using the same disk for TM backup under Yosemite and still use it to restore ML if you want, but the down side is if the disk starts to get full, the older backups (including potentially ML) will get purged off.

Is there something I should know about the Fusion Drive before having it erased in the process?

Nope... to you and the system the Fusion drive looks like one drive and the install works the same.

I was told that the OS (Mountain Lion in that case) is installed on the SSD portion of the Fusion Drive. Will Yosemi be installed too on the SSD portion of the FD?

That is not how it works. Fusion works at the bit level on the drive(s) and moves the most frequently accessed data to the SSD. That may or not be parts of the OS.

Lastly, what about ML? Gone for always?

A Yosemite install to the ML drive will overwrite the ML recovery partition with a Yosemite recovery partition, so yes, your ability to do a reinstall of ML would be gone. If that is important, you might want to redownload ML from your purchases list and use the installer to make a USB installer key and set it aside.

Or you can always restore from the TM backup like I mentioned earlier.

The only issue with restoring from either TM or CCC, is you will be restoring back to a point in time you had ML, so any data added (like documents) between the Yosemite install date and the restore to ML would need to be manually moved over to the restored ML setup in some way.

 

[Racineur]

Thanks a lot. I will proceed in a few days. Hope I won't mess up my things...