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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Notebooks > Formatting an SSD

Formatting an SSD
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Aug 20, 2010, 06:51 PM
 
Hi,

I want to install a new copy of Mac OS X from scratch. However, since SSD's degrade I was wondering whether it's a good idea. I heard that there's a way to do it without SSD degrading due to all the write that's gonna happen in the next day or so. Anyone know what I'm talking about?

Thanks!
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Aug 20, 2010, 06:58 PM
 
If you're really worried about it, the only thing you can really do is to boot into another OS that supports TRIM and reformat it there. I'm betting on 10.6.5 bringing TRIM support to OS X, though, so you could just hold out a bit if you feel like gambling on that.

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Aug 20, 2010, 10:07 PM
 
I guess; I also heard something about securely erasing the drive... overwrite will cause the SSD to reset itself or something like that but I cannot find anything about it when I need it :/
MacBook Pro 15" Intel Core i7 2.66Ghz/4GB/GeForce 330GT M 512MB/Corsair 128GB SSD
Mac Pro coming soon
iPhone 4 32GB Black
     
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Aug 20, 2010, 10:14 PM
 
You can do that by doing a "secure erase" in an OS that supports TRIM.

Whatever you do, do not use any of the OS X Disk Utility's secure erase options — if you zero all data or do a 7-way rewrite on an SSD, you will write to every free block on the drive, which is pretty much the worst thing you can do to an SSD on a system that doesn't support TRIM.

Myself, I'd just hang tight for a couple of months and see if 10.6.5 includes the long-overdue TRIM support. Hints of it showed up in 10.6.4, and 10.6.5 has been taking long enough that it's plausible that they could be working on this.

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Aug 21, 2010, 07:41 PM
 
Damn... thanks a lot for the heads up! Didn't know the secure erase meant I would need an OS with TRIM support still. I guess I'm gonna wait and then do it.

Thanks a lot!
MacBook Pro 15" Intel Core i7 2.66Ghz/4GB/GeForce 330GT M 512MB/Corsair 128GB SSD
Mac Pro coming soon
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Aug 31, 2010, 02:30 AM
 
Yes, it is possible on an intel Mac to restore your SSD to full speed without a Trim command. I just undertook this task with an Intel G1 SSD. As other posters have mentioned DO NOT ERASE OR ZERO THE SSD WITH DISK UTILITY. That merely marks EVERY block of the SSD as dirty and you end up with an even slower writing SSD. SSD's need their blocks marked as unused and that is possible with TRIM, but we don't have that option under OSX. Also, my Intel G1 SSD has no Trim support.

Windows users have the HDD Erase utility that can be run from a DOS boot disk. After a few frustrating attempts to create a DOS boot disk under VM fusion and Windows XP, I gave up on that route. Instead I found a nice equivalent that runs on a live Linux distro... gparted.

You can find it at... GParted -- Live CD/USB/PXE/HD
Grab the iso and burn it to CD.

Boot your Mac with the CD to run it.

There are numerous steps and you need to type in commands

How to secure erase your SSD's on a Mac - Mac Forums details the process (sorry to link out of the forum, but it is too much to rewrite.

Also, https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase has the info about the actual command line work.

My notes...
Be sure to clone your SSD first. This process with completely ERASE it and mark all the blocks as unused. Once that is done, you'll restore your backed up data back to the SSD.

On a MacBook pro, you DO indeed get the linux GUI, so it is easy to determine the device. In my case it was sdb when the SSD was in a USB dock. I did not need to detach all my other drives, but was careful about typing in the right device. Yes, this works with the SSD in a USB dock!

As the author stated, the first time you try

hdparm -I /dev/sdb

you will get an error. Do it again, and the error clears.

You want to secure erase, NOT enhanced security erase.

Took just over 2 min on a 160 GB intel G1 SSD.

Follow the commands carefull. It also helps to change the instructions to courier font for easier reading.

Yes, there is way on a Mac to do this without Windows!
     
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Aug 31, 2010, 02:55 PM
 
Yep, that's why I referred to using an OS that supports TRIM, rather than any specific OS. You can do it in either Windows 7 or Linux.

I still would prefer to wait for 10.6.5 and see if there's any news on the TRIM front, though, as it'd be a lot more convenient.

Ticking sound coming from a .pkg package? Don't let the .bom go off! Inspect it first with Pacifist. Macworld - five mice!
     
   
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