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Can I delete my old OS off my hard drive?

I have a mid 2012 MacBook Pro which I’ve put an ssd in the optical drive. This I now use as my startup disk and the computer runs a lot faster. Only problem is - there’s an old OS on my HDD. Is there a way to delete it? Feels like wasted space and messy.


thanks

MacBook Pro 13″, macOS 10.15

Posted on Oct 1, 2020 2:54 PM

Reply
Question marked as Top-ranking reply

Posted on Oct 2, 2020 5:17 PM

Ash Jones wrote:

So you’re saying I need to wipe what’s on the HDD currently in order to do it? In that case why bother with FileVault?

I may have misinterpreted what you were requesting in your original post. I thought you wanted to securely erase the original drive. I'm always looking out to protect private information and data and the method I outlined in the previous post would ensure that your private data was inaccessible.


To simply re-use the drive for extra storage you can use Disk Utility to erase the hard drive as GUID partition and MacOS Extended (Journaled). Just make sure to copy off any data from the hard drive you want saved before erasing the hard drive. It is too difficult to just remove the OS system files from the drive. You are much better off performing a full erase on the hard drive.


if the hard drive SATA cable failed, would it damage the drive?

It won't normally damage the physical drive. Unfortunately the symptoms of a defective cable vary greatly and may not be noticed at first. A defective cable can manifest by causing the drive to take longer to transfer data since errors are introduced requiring the system to send the data to the drive again. Worst case it can prevent communication with the drive altogether until the cable is replaced.


The cable has an extremely high rate of failure in the 13" model especially when used with an SSD, but it can also affect the hard drive (probably less noticeable if you are not reading & writing to it at the same time as would happen if it was still the boot drive).


Also are you saying to replace it because it’s been a few years now just get a new one? Or is there a specific SATA cable I need to look out for?

After several years of using the laptop the hard drive SATA cable tends to become worn where it can affect the performance of the drive or even prevent access to the drive. The cable failed so often that Apple at one time would actually replace the cable for free even it there was no apparent failure. This is the only time in 20 years that I recall Apple proactively replacing a part so it speaks volumes how prone this cable is to failing. Apple made the cable a bit thicker to minimize the chances of a replacement cable from having the same failure, but it is unlikely you will be able to purchase the newer style cable.


OWC sells replacement hard drive SATA cables for the 2012 MBPros:

https://eshop.macsales.com/search/?q=hard%20drive%20cable&filter.catidpath=3406/3410


If everything is working, then you can leave things alone, but if you encounter odd or intermittent issues, then maybe this cable is the problem or having the SSD in the optical drive bay may be the problem. I'm only suggesting to swap drives because I've seen lots of reported issues when using an SSD in the optical drive bay on Apple laptops especially for a boot drive. Apple really only designed the SATA controller, connector & cable to work with a really slow optical drive and not a high speed SSD. Personally I feel a hard drive is better off using the Optical drive bay because the hard drive has slower transfer rates and is less likely to have problems.


5 replies
Question marked as Top-ranking reply

Oct 2, 2020 5:17 PM in response to Ash Jones

Ash Jones wrote:

So you’re saying I need to wipe what’s on the HDD currently in order to do it? In that case why bother with FileVault?

I may have misinterpreted what you were requesting in your original post. I thought you wanted to securely erase the original drive. I'm always looking out to protect private information and data and the method I outlined in the previous post would ensure that your private data was inaccessible.


To simply re-use the drive for extra storage you can use Disk Utility to erase the hard drive as GUID partition and MacOS Extended (Journaled). Just make sure to copy off any data from the hard drive you want saved before erasing the hard drive. It is too difficult to just remove the OS system files from the drive. You are much better off performing a full erase on the hard drive.


if the hard drive SATA cable failed, would it damage the drive?

It won't normally damage the physical drive. Unfortunately the symptoms of a defective cable vary greatly and may not be noticed at first. A defective cable can manifest by causing the drive to take longer to transfer data since errors are introduced requiring the system to send the data to the drive again. Worst case it can prevent communication with the drive altogether until the cable is replaced.


The cable has an extremely high rate of failure in the 13" model especially when used with an SSD, but it can also affect the hard drive (probably less noticeable if you are not reading & writing to it at the same time as would happen if it was still the boot drive).


Also are you saying to replace it because it’s been a few years now just get a new one? Or is there a specific SATA cable I need to look out for?

After several years of using the laptop the hard drive SATA cable tends to become worn where it can affect the performance of the drive or even prevent access to the drive. The cable failed so often that Apple at one time would actually replace the cable for free even it there was no apparent failure. This is the only time in 20 years that I recall Apple proactively replacing a part so it speaks volumes how prone this cable is to failing. Apple made the cable a bit thicker to minimize the chances of a replacement cable from having the same failure, but it is unlikely you will be able to purchase the newer style cable.


OWC sells replacement hard drive SATA cables for the 2012 MBPros:

https://eshop.macsales.com/search/?q=hard%20drive%20cable&filter.catidpath=3406/3410


If everything is working, then you can leave things alone, but if you encounter odd or intermittent issues, then maybe this cable is the problem or having the SSD in the optical drive bay may be the problem. I'm only suggesting to swap drives because I've seen lots of reported issues when using an SSD in the optical drive bay on Apple laptops especially for a boot drive. Apple really only designed the SATA controller, connector & cable to work with a really slow optical drive and not a high speed SSD. Personally I feel a hard drive is better off using the Optical drive bay because the hard drive has slower transfer rates and is less likely to have problems.


Oct 1, 2020 9:23 PM in response to Ash Jones

If the old hard drive boots, then enable Filevault on it and let Filevault finish encrypting. Afterwards you can boot to the SSD and simply use Disk Utility to erase the hard drive which will destroy the Filevault encryption key making the data on the hard drive inaccessible.


FYI, I would move the SSD to the main drive bay as the SATA controller for the optical drive bay is not the best option for an SSD plus the SATA cable may not be sufficiently shielded to handle the higher transfer rates of an SSD.


Also if you the 13" model you should replace the hard drive SATA cable in the main drive bay since this cable has an extremely high rate of failure.

Can I delete my old OS off my hard drive?

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