Existing users, 
Reminder: Keep some free space on your iPhone
Posted 16 August 2007 @ 9am in Troubleshooting
We recently received an email from iPhone Atlas reader Larry who wrote:
“How much memory should someone leave free on the iPhone for it to function properly? […] In my case, I added a movie to my iPhone leaving 600 mb left on an 8 gb iPhone. While the iPhone worked properly, I started noticing behavior such as the home screen stuttering when returning to it (pressing the home button, the iPhone started returning to the home screen, stopped, then again went through the animation of widgets returning to the screen). I deleted the movie and this behavior stopped. Perhaps that’s a coincidence, but I took it as an indication that I was approaching the limit of how much I could put on my iPhone without affecting it.”
It’s no coincidence, Larry. As we noted in mid-July, it appears that, like its desktop relative Mac OS X, the iPhone’s OS X operating system needs some head-room on the internal flash memory in order to operate properly. iPhones filled to the brim with data can exhibit issues with crashes in applications, freezes and others.
The desktop version of Mac OS X requires at least 10 percent of the volume it is contained on as free space in order to maintain the integrity of the file system. However, even with 10 percent free space, Mac OS X’s use swap files - as well as extra data generated by third-party application caches, etc. - can quickly put you back into a position of possible directory/file damage.
We’re not sure yet how exactly the iPhone’s OS X filesystem works relative to the full-blown version of Mac OS X, but for if you’re experiencing repeated problems similar to those aforementioned, try clearing up about 10 percent of its free space (by reducing the number of files/data synced to the device in iTunes) and check for alleviation.
Feedback? info@iphoneatlas.com.
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1 Comment
Posted by icruise_general
16 August 2007 @ 12pm
I haven’t experienced anything that leads me to believe that only having 600MB of free space will cause problems. I rarely have more than 300MB or so free on my iPhone and have never experienced those problems. I also think that if leaving some free space was so critical to normal iPhone operation that Apple would have made it clear to the user (via the manual and software prompts) that they should do so. Heck, if it was so critical, why wouldn’t they just have left a section of the disk reserved for things like cache, separate from the space that the user uses for videos, music, and photos? In fact, they may have done this — we don’t know. It just seems odd that they would not do one or the other of these things, since with the iPod we don’t have to worry about leaving a certain percentage of the disk empty, and they would know that people would want to fit as much in their limited storage space as they possibly could.
In short, I’m not convinced that the commonly accepted practices for OS X computers apply to the iPhone. You probably shouldn’t fill it absolutely full, but do we have any actual input from Apple or hard proof that a certain amount of space needs to be left empty?