Is it True There Should Always be 20 to 25% of Free Space At All Times?

Alvin777 wrote:

Hello Apple friends, I read, is it true there should always be 20 to 25% of free space of your drives' physical space at all times when running macOS, especially the latest, Sonoma or Sonoma has fixed this and you can max the capacity of your SSD (or hardisk) to 100% nowadays and it won't decrease the life of your SSD too soon from the average lifespan and things would still be fast and stable?

I also heard, the free space could be just the same amount as your RAM?

Which "school" is the correct one?

Thank you in advance.

Godspeed, have a great day- God bless Apple users.

The Operating System will need a certain amount of Empty Space in order to boot up.

Without that empty Space available to the Operating System, the life span of the drive will be very much longer

Longer, in that, the computer will Cease to Boot Up at all even in Safe Mode

There is, No Fix from Apple, to how the user ( You ) manages the defined Capacity of the Drive.

They figure, the user is responsible for working with what they have purchased in specific regards to the Size of the Internal Drive

20% to 25 % of the Total Drive Capacity, is generally believed to be the Optimum percentages of Empty Space

Less that that, may actually have the Opposite Effect

The computer will always be searching for Empty Space ( More Power consumed there ) as it tries to Write to the Drive

As it searches and writes to the drive, the changes may require over-writing some files which in turn increased the Number to Writes to the drive

It has nothing to do with the OS. An SSD needs space to do garbage collection to reset the storage to writeable for deleted items. You cannot overwrite the storage like on a hard drive. It must first be reset to writeable before it can be re-used. This process will normally move things around so the free space is needed.

" As it searches and writes to the drive, the changes may require over-writing some files which in turn increased the Number to Writes to the drive "

Perhaps I need to clearly " Overwrite " as in mark as Rewritable and Reusable

Thank to previous posting for catching that

Alvin777 wrote:

Hello Apple friends, I read, is it true there should always be 20 to 25% of free space of your drives' physical space at all times when running macOS, especially the latest, Sonoma or Sonoma has fixed this and you can max the capacity of your SSD (or hardisk) to 100% nowadays and it won't decrease the life of your SSD too soon from the average lifespan and things would still be fast and stable?

That's one long question. The answer is a firm "No".

I also heard, the free space could be just the same amount as your RAM?

Somewhat true.

Which "school" is the correct one?

Those are two different questions. I'll clarify...

You don't need to worry about the life or speed of your SSD. That's just internet misinformation. It's not true.

There is no percentage of hard drive space that you need to keep free. Ideally, you should have 100-200 GB of free storage available. If you have a 120 GB SSD, that's going to be a challenge.

Note that I said "free" storage. In most places, the operating system is going to tell you about "available" storage. Ignore that. "Available" storage is nonsense and means nothing. Disk Utility will tell you the actual "free" storage in the big bar chart. That's what you want to look at.

If you run low on storage, your computer will run more slowly and you'll start to have strange problems. If you run completely out of storage, that can be a catastrophic failure resulting in total data loss. Consider yourself warned.

Unfortunately, the operating system doesn't warn you until you run totally and completely out of storage. Once you get to this point, you'll get totally confused. Up will be down. Black will be white. You'll furiously delete files only to see your available storage go down. Everything you do will only reduce your storage. You'll get frustrated, question your sanity, and walk away in a huff. Three days later, everything will be fine. It'll be like the operating system is gaslighting you. Then, in a couple of weeks, it all starts again. You can avoid this by keeping 100-200 GB of "free" storage at all times.

User wrote “ I also heard, the free space could be just the same amount as your RAM? “

Not true

“ There is no percentage of hard drive space that you need to keep free. Ideally, you should have 100-200 GB of free storage available “

If we combine the users earlier statement with a previous statement.

To attain the amount of Empty Space on the drive equal to the installed RAM installed on this computer and to maintained the " 100-200 GB  free storage space. "

It would require a Mac Studio Pro totally Maxed out with 196 Unified RAM

Perhaps a MacBook Pro M2 Pro 14” form  2023 with 96 Unified RAM 

Then the MacBook Pro M2 Pro configuration  also with 96 Unified RAM

Surely the types of configurations will be doing much more than general Internet Surfing and emails 

Therefore it would reasonable to believe the 100 - 200 GB Of Empty Space would be eaten up very quickly.

Just saying  

MacOS is a UNIX operating system, and historically, whether Apple or another vendor, the operating system needs some reserve storage for normal operation, to say nothing of ordinary user storage. Exhaust that storage and you end up with a paperweight Mac that cannot boot. That is not theory as it happened to a friend's daughter last year.

The previous figures we suggested for earlier releases of (smaller) macOS and other UNIX operating systems were approximately 10 - 15% free storage at all times. Due to the increasing resource demands of evolving releases of macOS, I don't believe 20 - 25 % free storage retention is now unrealistic. One should temper the version of macOS installed with the original drive capacity which may require offloading movies, photos, etc. to external storage.

no

but you can leave space to ensure quick compeletion of the work