User profile for user: Cursumperficio
Cursumperficio Author
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Logic Pro 12 requires free internal disk space even when Sound Library is fully relocated to external SSD

I’m experiencing a confusing behavior with Logic Pro 12 regarding Sound Library installation, and I’d like to confirm whether this is expected or a known limitation.


Setup


  • Logic Pro 12.0.1
  • macOS 26.2
  • Internal system disk with limited free space
  • External SSD formatted as APFS
  • Sound Library relocated to the external SSD using Logic Pro’s Sound Library Manager


What is confirmed


  • The Logic Sound Library is fully located on the external APFS SSD.
  • /Library/Application Support/Logic is correctly redirected to the external drive (verified via symlink).
  • Existing content (Alchemy, Sampler/EXS instruments, Ultrabeat, etc.) is already on the external SSD.
  • The external SSD is mounted before launching Logic and has sufficient free space.


The problem


When attempting to download additional sound content, Logic Pro still checks the internal system disk for a free space and fails if that space is not available even though the external SSD has plenty of free space and is correctly configured.


Apple documentation


According to Apple Support article “About the Logic Pro and MainStage sound library on Mac” (support.apple.com/en-us/125036), when the sound library is stored on an APFS-formatted external drive, Logic should be able to update and install new content on that external storage.

However, in practice, Logic Pro still appears to require significant temporary internal disk space during the download/unpack/validation phase, regardless of where the final library is stored.


Question


  • Is this internal disk usage during sound library installation intentional and unavoidable in Logic Pro 12?
  • Or is this a bug / unintended behavior specific to Logic Pro 12?


Any clarification from Apple moderators or users with similar experience would be appreciated.

Mac mini (M4, 2024)

Posted on Feb 23, 2026 8:35 PM

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User profile for user: D.I. Johnson
D.I. Johnson
User level: Level 8
35,927 points

Posted on Feb 24, 2026 6:51 AM

Cursumperficio wrote:

I’m experiencing a confusing behavior with Logic Pro 12 regarding Sound Library installation, and I’d like to confirm whether this is expected or a known limitation.
[...]
Question•

Is this internal disk usage during sound library installation intentional and unavoidable in Logic Pro 12?
• Or is this a bug / unintended behavior specific to Logic Pro 12?

Any clarification from Apple moderators or users with similar experience would be appreciated.


The behavior you are experiencing makes perfect sense to me from the perspective of a long time Mac user.


It is typical of the OS to download updates, upgrades and installation data into a location on the startup drive before processing it for installation at the appropriate location, whether that location is the Applications or Downloads folder or a particular app related destination folder such as Logic's library.


So yes, it's intentional and likely unavoidable and not a bug or unintended behavior.


If you maintain a healthy amount of space free on your startup drive then this situation should be invisible in the background and cause no problem. A healthy amount of free space would be 10%-15% of the total capacity of the startup drive or a very minimum of ~50 GB. Of course this can be difficult if one has a very low capacity startup drive - 256 GB or less.

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User profile for user: D.I. Johnson
D.I. Johnson
User level: Level 8
35,927 points

Feb 24, 2026 6:51 AM in response to Cursumperficio

Cursumperficio wrote:

I’m experiencing a confusing behavior with Logic Pro 12 regarding Sound Library installation, and I’d like to confirm whether this is expected or a known limitation.
[...]
Question•

Is this internal disk usage during sound library installation intentional and unavoidable in Logic Pro 12?
• Or is this a bug / unintended behavior specific to Logic Pro 12?

Any clarification from Apple moderators or users with similar experience would be appreciated.


The behavior you are experiencing makes perfect sense to me from the perspective of a long time Mac user.


It is typical of the OS to download updates, upgrades and installation data into a location on the startup drive before processing it for installation at the appropriate location, whether that location is the Applications or Downloads folder or a particular app related destination folder such as Logic's library.


So yes, it's intentional and likely unavoidable and not a bug or unintended behavior.


If you maintain a healthy amount of space free on your startup drive then this situation should be invisible in the background and cause no problem. A healthy amount of free space would be 10%-15% of the total capacity of the startup drive or a very minimum of ~50 GB. Of course this can be difficult if one has a very low capacity startup drive - 256 GB or less.

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User profile for user: D.I. Johnson
D.I. Johnson
User level: Level 8
35,927 points

Feb 24, 2026 9:50 AM in response to Cursumperficio

Cursumperficio wrote:

Oh, I get it. My startup drive is 256 GB, unfortunately. I'll try to free up some space before installing. Hopefully, it won't stay on my startup drive afterwards. Thanks for the reply.

You're welcome.


MacOS will normally erase the raw download after it has done the proper installation of the downloaded files, so that stuff should not remain on your startup drive.


Some users would buy a fast external SSD and install macOS on that and use it as the startup drive for a Mac with limited internal storage. They could then, of course, also install Logic Pro and its libraries as well. Something you might consider doing yourself.

How to use an external storage device as a Mac startup disk - Apple Support



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Logic Pro 12 requires free internal disk space even when Sound Library is fully relocated to external SSD

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