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Why is it different to update iPhone thru iTunes vs iPhone 189MB vs 803MB?

B

blackbirdz

macrumors member
Original poster
Apr 2, 2012
72
14
I updated my 4S from IOS 5.0.1 to IOS 5.1 via iPhone itself. I remember the file is only around 189MB and update success.

Today, I played around with iTunes with my iPhone connected. When I click "Restore" - iTunes was going to update the iPhone with the latest software even though iTunes knew that the iPhone already had 5.1 installed.

Now iTunes is downloading the update (5.1) - and I notice that the file being downloaded is 803.0MB.

My question is about file size: 189MB vs 803.0MB.
Is there anything different? With that huge gap, I assume there must be something different?


Is it like Full Installation vs Upgrade? Is it better to have clean installation (full install) instead of upgrade? It shouldn't make any different. In Windows OS, it's better to have full clean installation instead of upgrade.

Can someone verify? And which one is better?
 
Last edited:
itunes downloads the whole firmware, while your phone only downloads the files that need updating (delta update).
 
It's because when you update your phone, it only downloads the parts of the OS that have changed, resulting in a smaller download. It's called a delta update.

When you restore in iTunes, it downloads the entire operating system.
 
iTunes will still do a delta on the phone, it just downloads the whole ipsw just in case you need to do a full restore.
 
lordofthereef said:
/thread
Click to expand...

Not really. People have only explained what is happening, not why it happens.

The reason that iTunes downloads the entire iOS is so that you can perform restores without having to re-download anything again, where as updating on your phone is a one time thing.

I would be surprised if you could do a 'full clean installation' upgrade via the phone without losing a lot of user data, but hey, you never know... I'm honestly not sure though if when you update via iTunes, it does a clean wipe or not. I'd be interested to hear from others? It would be nice if it did. Just like how you're supposed to reinstall a clean copy of an OS on a computer; I'm sure it's good for phones as well.

As to which one is better, the iTunes download imho. Always good to have a copy on hand for when you may need it - also if you have multiple devices to update (as in for you and another family member), as you'll only have to download it once.
 
djdover said:
Not really. People have only explained what is happening, not why it happens.

The reason that iTunes downloads the entire iOS is so that you can perform restores without having to re-download anything again, where as updating on your phone is a one time thing.

I would be surprised if you could do a 'full clean installation' upgrade via the phone without losing a lot of user data, but hey, you never know... I'm honestly not sure though if when you update via iTunes, it does a clean wipe or not. I'd be interested to hear from others? It would be nice if it did. Just like how you're supposed to reinstall a clean copy of an OS on a computer; I'm sure it's good for phones as well.

As to which one is better, the iTunes download imho. Always good to have a copy on hand for when you may need it - also if you have multiple devices to update (as in for you and another family member), as you'll only have to download it once.
Click to expand...

I am almost certain it does a clean wipe. I say this because, unless you "restore from backup", the phone still needs to be activated. If you go ahead and activate it, it will be like a brand new phone. No settings are saved. Only way to restore settings is to reloead the data from the backup, AFAIK.
 
I think it also depends on what you're upgrading. If its like 5.0.1 to 5.1 then iTunes will do a delta update, but if it's like iOS4 > 5, then it will need to do a full restore then restore all your content.
 
Tea-Aholic said:
I think it also depends on what you're upgrading. If its like 5.0.1 to 5.1 then iTunes will do a delta update, but if it's like iOS4 > 5, then it will need to do a full restore then restore all your content.
Click to expand...

That makes sense, as the .1 updates in iTunes don't require a backup and restore... that would be a PITA.

I'm out of the upgrade business until there is an untethered jailbreak for a newer version of iOS though...
 
Full clean install from iTunes to IOS 5.1 - here it is

I just did a full clean installation via iTunes. So for those of you wondered how clean install thru iPhone work out - here it is:

1. Open iTunes and connect your phone.

2. ***** Make sure to back up your data first!!! ****** before going to the next step.

3. After backing up, click Restore and iTunes will do the rest very simple.

4. iTunes will download the whole installation package file size: 809MB.

5. It will WIPE OUT the entire data on your phone including the OS (no need to be panic here)

6. After installation is complete - iPhone will reboot itself.

7. And done! Basically you now have a phone with new OS & original factory setting. In here iTunes will ask you whether:

a. You want to use it now (with no data of course). If so, you just need to disconnect the phone.

b. Restore your data (e.g. SMS, picture, video). If so, choose this option and iTunes will restore the data from the back up you did on Step 2 above (this is what I chose).

The whole thing took around 15 minutes or possibly less. It's very simple, nothing to be scared of.
 
blackbirdz said:
I just did a full clean installation via iTunes. So for those of you wondered how clean install thru iPhone work out - here it is:

1. Open iTunes and connect your phone.

2. ***** Make sure to back up your data first!!! ****** before going to the next step.

3. After backing up, click Restore and iTunes will do the rest very simple.

4. iTunes will download the whole installation package file size: 809MB.

5. It will WIPE OUT the entire data on your phone including the OS (no need to be panic here)

6. After installation is complete - iPhone will reboot itself.

7. And done! Basically you now have a phone with new OS & original factory setting. In here iTunes will ask you whether:

a. You want to use it now (with no data of course). If so, you just need to disconnect the phone.

b. Restore your data (e.g. SMS, picture, video). If so, choose this option and iTunes will restore the data from the back up you did on Step 2 above (this is what I chose).

The whole thing took around 15 minutes or possibly less. It's very simple, nothing to be scared of.
Click to expand...

That's not a "full clean installation" you did. To be "clean" you should have chosen option "a.".
 
enoC said:
That's not a "full clean installation" you did. To be "clean" you should have chosen option "a.".
Click to expand...

Same thing, I mean technically going by what you are saying, anything I do on my phone afterwards makes it "not a full clean installation". He did do a clean install, then proceeded to restore his data.
 
Tea-Aholic said:
Same thing, I mean technically going by what you are saying, anything I do on my phone afterwards makes it "not a full clean installation". He did do a clean install, then proceeded to restore his data.
Click to expand...
You clearly misunderstood what I said! And you clearly do not know much about this subject. It's not the same thing.

Let's say you have a sw problem with your iPhone. You follow the guide, and chooses option b at the end. And then you wonder why you still got the sw problem, after restoring the backup.
This is because the problem could be in the backup. If you had chosen option a and never used a backup, you wouldn't have the problem.
Do you understand the difference?
 
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