How could lack of free space affect the performance of an iPhone?

[kenny1999]

Apple's official site suggests their users maintain at least 1GB of free space for best performance.

In fact, as far as I know, iPhone's storage is a Solid State Drive, rather than a mechanical drive. How could lack of free space affect the performance of an iPhone?

By the way, when performance is said to be affected, or not at its peak state, what does it actually mean? Does it mean it will more likely to crash or make mistakes or cause data corruption? Or does it actually mean probably causing a very short delay, probably less one second that we don't notice, but everything will work just fine?

[Sensei]

Twenty years ago I managed to "destroy" ("render useless") Nokia's then best and most expensive phone by filling up all the internal memory.

It could not restart anymore.

The system reads and writes data from the disk (regardless of the type). If OS can't write, the user is screwed.

The Live Linux flash drive is particularly prone to this problem as the storage is emulated in the physical memory of the computer instead of the physical HDD/SSD/NVMe. On my outdated Athlon 15+ years old with just 2 GB, just watching YouTube videos for two-three hours, on the Linux Live pendrive (without installation of Linux on disk) is enough to make the OS crash permanently to the point where the mouse pointer is frozen and the keyboard is unresponsive.

 

31 minutes ago, kenny1999 said:

By the way, when performance is said to be affected, or not at its peak state, what does it actually mean?

The system will try to 1) archive some files 2) delete something 3) shut down and never be able to wake up....

 

Edited September 25, 2023 by Sensei

[kenny1999]

5 hours ago, Sensei said:

Twenty years ago I managed to "destroy" ("render useless") Nokia's then best and most expensive phone by filling up all the internal memory.

It could not restart anymore.

The system reads and writes data from the disk (regardless of the type). If OS can't write, the user is screwed.

The Live Linux flash drive is particularly prone to this problem as the storage is emulated in the physical memory of the computer instead of the physical HDD/SSD/NVMe. On my outdated Athlon 15+ years old with just 2 GB, just watching YouTube videos for two-three hours, on the Linux Live pendrive (without installation of Linux on disk) is enough to make the OS crash permanently to the point where the mouse pointer is frozen and the keyboard is unresponsive.

 

The system will try to 1) archive some files 2) delete something 3) shut down and never be able to wake up....

 

I certainly don't believe that a 64GB iPhone that remains only 100MB of free space would make it shut down and never be able to wake up. That would be the world news if that's the case.

Edited September 25, 2023 by kenny1999

[swansont]

IIRC the hard drive memory is used by the OS when swapping info in and out of RAM.

 

6 hours ago, Sensei said:

Twenty years ago I managed to "destroy" ("render useless") Nokia's then best and most expensive phone by filling up all the internal memory.

The phones of 20 years ago were not the same as the smartphones that came after, like the iphone.

[Sensei]

1 hour ago, kenny1999 said:

I certainly don't believe that a 64GB iPhone that remains only 100MB of free space would make it shut down

This is not exactly what I said. My phone shut down due to battery drain. Every attempt to restart it ended in failure.

It failed because the operating system could not save a certain file during the startup process. Free space was counted in KB, not MB.

39 minutes ago, swansont said:

The phones of 20 years ago were not the same as the smartphones that came after, like the iphone.

It doesn't matter. It's actually worse because it is Linux.

I can cause Linux to stop working without any problems.. I even gave an example with Linux on Live flash drive.

Try

dd if=/dev/zero of=file bs=16M status=progress

or

dd if=/dev/random of=file bs=16M status=progress

..and wait until the entire disk is full..

 

39 minutes ago, swansont said:

IIRC the memory is used by the OS when swapping info in and out of RAM.

Exactly. That's why Windows pre-allocates space in the hidden files hiberfil.sys and pagefile.sys

They are the size of the RAM. So if you have 24 GB, it will be 48 GB lost from the primary partition.

You can regain this space by in admin mode:

powercfg -h off

but machine won't hibernate anymore.

You can also turn off the page file and get double the space (for example, 2x 24 GB).

I do this often on 120 GB drives, because the loss of 32-48 GB is unbearable..

1 hour ago, kenny1999 said:

That would be the world news if that's the case.

Every operating system is vulnerable to such attacks. Especially customer devices.

It's just a matter of how much exhausted physical memory and storage is needed to operate.

1 hour ago, kenny1999 said:

remains only 100MB of free space

..we are talking about free space counted in kilo bytes..

 

BTW, 10, 100 MB, 1 GB, 100 GB (does not matter!), free memory, does not guarantee the correct operation of the application if it needs it as a continuous memory region..

Memory can be fragmented.

https://en.wikipedia.org/wiki/Fragmentation_(computing)

 

 

Edited September 25, 2023 by Sensei

[Ghideon]

7 hours ago, kenny1999 said:

Apple's official site suggests their users maintain at least 1GB of free space for best performance.

Where? Maybe this link to apple support: https://support.apple.com/en-us/102598, it explains the reason. (Highlighted below)

Quote

For best performance, try to maintain at least 1GB of free space. If your available storage is consistently less than 1GB, your device might slow down as iOS or iPadOS repeatedly makes room for more content.