Clean Install Yosemite onto new SSD (Also, what is TRIM?)

Yes. Absolutely you should be able to do that exactly. Your machine might be one to look into Trim Enabler. I have used it on my 128gb Samsung 840 pro in my 2012 Mac Mini running Mountain Lion and I still get 360 mbps-write 500+ mbps-read after 2 years. I assume the with the transition to the all PCIE flash architecture, Apple has Trim taken care of.

Just plug in the drive into a SATA to USB cable then to your computer, Go to disk utility and format it to Mac OS extended, Download Yosemite and when it asks which drive to write to, install it to the new, external drive.

Since you have a 15" MacBook Pro, look into how your graphics card will be affected by the change in OS. Each Apple OS has different driver sets and some work better than others. Yosemite seems to be pretty clean but definitely check it out since the whole point of owning a 15" MacBook Pro is to utilize a GPU... Good Luck Mate! Let us know how it works out for you!

I agree that the new SSD's can get along without trim. I would guess that you will buy a new Mac someday before you see any performance deterioration of the SSD with no trim.

TRIM is very important. On my Mountain Lion Mac Mini if I turn my trim off for a month my Samsung 840 pro write speeds will go down to 100mbps and reads to 300mbps. When i turn TRIM enabler back on, it takes a day or so but my speed returns and the drive is "TRIMmed". Like my other post said, Apple probably has TRIM figured out for Yosemite but you should download Black Magic to test your SSD's speed regularly (weekly) to make sure TRIM is actually working right. If you start losing SSD speed, look into Yosemite TRIM enabler work arounds.

OP can we get an update on this thread, I'm in exactly the same situation with exactly the same Macbook Pro model. Did you manage to change across to a SSD using the steps you listed in your post?

Thanks 🙂

Apple has their SSD specially made for them. You probably won't find one aftermarket with native trim support.

I've seen where others have posted that Samsung 840 EVO works fine without enabling TRIM. Software controllers on the new drives are getting better without the need for outside TRIM software. You might also check out OWC website for their Mercury SSDs. OWC states that they do not recommend enabling TRIM. Says their SSD has it's own garbage collection built in and doesn't need outside help.

I wouldn't worry about enabling TRIM. If you do find that your drive is slowing down, you can always use Trim Enabler to turn it on and disable it at your liking.

I do have an OWC SSD drive. I have not enabled TRIM. It has been fine without it. It's the only one I've tried and it's an older 3G model, so I have nothing to compare it to. So far, it's been great compared to the old conventional hard drive. I don't think I could go back to the old drive now. I'm spoiled.

Odd as I have had no slow downs and I did not use trim with my Samsung 840 EVO but probably depends on how much you write to the SSD. If your SSD slows down and you do not have trim then just option boot, leave in this idle mode for a few hours and all the speed will come back as the garbage collection works which is slower than when trim is enabled.

There are a number of people here who have long time experience with SSDs and Trim. I am one of them.

For modern SSDs and modern OSX (Mavericks, and especially Yosemite) I strongly advise against installing the Trim command: this can lead to transfer issues on the file level (incurable) and in Yosemite you have to disable a whole security level. The Garbage control and overprovisioning in modern SSDs is VERY good and efficient. I used to install trim years ago, but without the hacking apps as there TrimEnabler (a complete disaster in the beginning) and Chameleon (better, but still a hack), I used the "hand method" of GrantPannell.

Hi,

I'd like also to have an update on the original question of the Yosemite clean install steps in the first post.

And if we would add one more step: 4) Connect old hard drive to USB and use Migration Assistant to transfer user settings/files and apps to SSD fresh Yosemite Installation.

Would that work as a replacement for other various guides using, e.g., CCC, to perform the SSD upgrade?

I somehow feel that it's better if the OS is clean installed in a new drive and after that settings/files are updated.

Thanks!

Thanassis

Hey Thanassis,

Just to confirm, since my post asking for an update I've actually followed the steps above by putting the OS onto my new SSD externally then swapping the HD out and booting up with a fresh install. All worked fine and the new crucial SSD runs Yosemite perfectly but I did cause an issue with migration assistant in that midway through backing up from my old HD it seemed to freeze/crash.

I've ended up plugging the HD in and transferring my content manually which for me was fine but just to let you know, the steps work and the error with migration assistant may well be down to an error on my part knocking the HD during the transfer.

Using the Migration Assistant looks attractive (settings and such come with it), but doing the transfer by hand has the advantage that you only have the things you did by hand; you "pay" for that advantage by having to install and do settings and connect libraries. I only once in my life used Migration Assistant.

Thanks for your comments.

Problem with 'transferring by hand' is that you have to re-install apps and repeat any custom configurations I have (e.g. macports). I'd like to avoid that by using some tool that do this transferring/migration into a clean installation.

Haven't tried yet, currently I'm waiting for my new Samsung SSD 850 Pro 256GB to be delivered!

Thanassis

Problem with 'transferring by hand' is that you have to re-install apps and repeat any custom configurations I have (e.g. macports)

Yes, but that is an advantage at the same time...

You can also use the Migration Assistant just for those difficult things and do the rest by hand.

Beautiful and very good modern SSD you ordered.

👿

Lex