

Ask HN: Why iOS started to require a lot of free space for updates? - aabalkan

I am using iOS since 5.x and in iOS 7, updates of sizes like 18 MB - 50 MB started to ask for free space of 800 MB - 1.5 GB on the phone. That sounds absurd. From a programmer point of view, what could be the reason every single update requires so much spare space on the disk?
======
jgeorge
The downloaded updates are just deltas from the previous release of the OS.
These updates are assembled into (more or less) a "new OS image" on-device and
then installed in the same manner a monolithic OS install is done. Since the
device needs to make a copy of the entire OS image, you need a ton of free
space.

Installing the "full" OS update from iTunes shouldn't require quite the large
amount of space on device, since tethered to iTunes the existing OS image can
just be replaced at once since the iTunes download is the full OS image and
not just a diff. The diff saves on network bandwidth at the cost of large
amounts of scratch space on the device.

------
throwwit
Probably to avoid people diff'ing the updates.

