What does a factory reset actually do?

74 viewsOtherTechnology

I am wondering how it really works and why for example if the device software seems broken. All it takes is a simple restore and it’s expected that it will all fix everything?

Also how come the restore partition never gets corrupted and is able to install the brand new software again and get it all working?

In: Technology

5 Answers

Anonymous 0 Comments

Imagine a room that’s all messy. There’s clothes all over the floor, objects out of place and it’s pretty dusty too.

Mom comes in and does what moms do best. She cleans it up and tidy’s the room back to how it’s supposed to be. Everything neat and organized and clean. That’s what a factory reset is.

Anonymous 0 Comments

About the first question: most times when you make changes to your software, for example by installing something or changing settings, those are applied incrementally, let’s say by adding a few files here and adding a line to a configuration file there, similar to how you’d edit a text document. Things can go wrong if you do this a lot, like files or lines in the configuration can be forgotten and just stay there as dead weight, or they can grow out of hand (imagine a long text document where you have a lot of references like “see page 25”, but then on page 25 it says “see page 58” and you have to follow the whole chain and maybe even go back and forth several times to find what you need). 

A “factory reset” is usually much more coarse. There is a specific copy of everything how it should be by default and whatever is there just gets deleted and replaces with that. That’s usually a much easier way to clean up all the forgotten junk and messy references than trying to “untangle” them while keeping the information in place.  

About your second question: restore partitions are usually read-only, or at least allow only very limited writing to install updates. It’s also usually only the manufacturer of the device that accesses them, so they know exactly how everything works and they are aware that corrupting anything there would be a huge problem, so they are extra diligent about anything they do related to the files there. 

Anonymous 0 Comments

Depends on the particulars of the device – it can mean any of a huge list of of things. The idea of course it the device matches the way it would have been after manufacture, but that can be achieved a lot of different ways depending on the device.

You mention a restore partition – for devices that rely on something like that the idea generally is that there’ll be a copy of the baseline setup of the device and it can be copied over the “real” partition to reset everything to how it was.

> how come the restore partition never gets corrupted

It’s certainly possible for it to have problems too, but in the scheme of using a restore partition generally the restore partition is either read-only (IE: nothing can every edit it directly) or at least the system is set up to rarely if ever touch it.

For the most part the point of factory resets is either to wipe personal data (like when selling a laptop to someone else) or try to fix a hard to debug issue that’s likely the result of a bug (so: something in the software made changes to the “real” data in a way that was unintended and is causing issues).

In either of those cases: a partition that by design isn’t being changed after it’s left the factory isn’t going to develop problems.

Anonymous 0 Comments

A factory reset is meant to restore the device to the state it was in when it left the factory. What exactly that means depends on the device.

Devices have multiple kinds of software and memory. Firmware is the base level of software that is stored in memory that is immutable under normal operation of the device.

For many simple devices, this is all the software they have: all other memory is reserved for user settings and data. In that case a factory reset might just mean wiping the main memory, so things go back to default settings and all the user data is gone.

More complex devices like your phone will also have system software like the operating system and built in applications stored in normal memory. They will often also store a pristine copy of the system software in a protected partition of the normal memory, or a dedicated memory module. A factory reset means both clearing the main memory and then copying the pristine copy of the system software back into place.

Anonymous 0 Comments

Imagine you have a really, really tangled rope. You could spend a lot of time untangling it, or you could just get a new rope.

Factory reset wipes everything you’ve done to the device, good or bad, back to the point where we are almost absolutely sure it works—the state it was in when you bought it.

The mechanics of it depend on the device itself. For some systems, it’s sufficient to literally just erase everything. Things like disk drives don’t really have a factory state aside from “nothing”, so it’s sufficient to just wipe all the memory. For more complex systems, you may have to download a replacement—for instance, you can “factory reset” a windows installation by reinstalling windows over the system.

There’s usually the ability to keep a part of memory that the computer is physically incapable of writing to, so it cannot change. A computer could have a second drive that’s disconnected and read-only, that only gets connected when a factory reset is requested. Oftentimes you really don’t need a lot of storage to store what to do for a reset (e.g., for the drive example, we basically just need to store instructions that say “wipe everything”), so it’s not a large overhead. Sometimes that responsibility is passed onto the user, like factory resetting a computer will often require the user to reinstall the OS themselves.