WHY is backing up and synching so slow?

Question

I know there are a number of solutions posted (I like this one, though have yet to try it: http://discussions.apple.com/message.jspa?messageID=7706721&tstart=0 ), but what I have found does not make any sense and I can't see why the iPhone is behaving so slowly visa vi synching and backing up. I started a backup yesterday at 03:20, and when I returned home (yes, these problems have caused me to go 2 days without a mobile phone -- thank goodness my car didn't break down and require me to call for assistance) at 17:20 it was only about 80% complete!?!! 14 hours and it only backs up 80%?? So I hit the "Transfer all purchases" item in the file menu and this cleared all my checked apps and then checked EVERY ONE so it tried to download all 250 or so apps that I usually swap in and out of my phone. The phone only supports 128 or so apps, so there's no point in loading more than that and I try to tailor my apps to the ones I feel like using on a given day or just to test some for a while. This did transfer my purchases so I had a copy of the apps I paid for on the phone on the computer, and as that was my main concern I decided to let the synch go. Well, 03:05 rolled around the following day (as it always does) and there was my iTunes, STILL ON THE "Y"s. It still wasn't even finished synching after all that time! I mean, we're talking only about 130 or so more apps -- a good chunk of the apps were already on the phone. And apps aren't big. What gives?
Anyway, that is my long exposition, but in summary, here is my question: WHY does synching and backup up take so unacceptably long? Let me quote you some numbers to see why I find this so unacceptable: USB 2.0 has a standard throughput of 40 MB per second. It theoretically can go faster and may in practice be slower, but for sustained transmission, it should be able to transfer data at this rate. So, for a 16GB iPhone, if you wanted to TRANSFER THE ENTIRE CONTENTS OF THE PHONE, it should take LESS THAN 7 MINUTES! USB CANNOT be the bottleneck. And if USB can do it in 7 minutes (and that's to transfer EVERYTHING: most syncs and backups are much MUCH less than that) there is no reason -- ABSOLUTELY NO REASON -- it should be all that much slower to synch or back up. If the blame lies with the iTunes software, then you need to ask yourself, why is iTunes trying to do this in real-time? Why not transfer the data raw, and end the "backup" lock so that the phone can safely be unplugged and then in the background transform the "raw" backup into the normal format backup, making it impossible to close iTunes before this is done. Sure, if iTunes crashes or the power goes out before the Backup is completed, you'd have a corrupt backup, but all iTunes has to add here is a file flag -- for instance, the existence of a raw backup file -- to know that it died during a backup conversion and it needs to start again. Further, it should keep around the previous backup until the new backup is fully transformed. This would not be hard to do and should easily keep initial backups under 10 minutes! Further, after the first backup, all subsequent backups should be incremental, and the phone should maintain an internal change log so that it can easily perform incremental backus sometimes instead of always requiring a full one.
As for synching, I will admit that is more complicated, but surely we can get it to a reasonable time frame. On the iTunes side, the apps and other data should be stored in a form that makes them "easy" to synch with the iPhone. Save the iPhone profile locally so that the data that needs to be transferred is "ready to go". Also, have iTunes maintain a "change log" since last synch, so it can easily keep track of any new, downloaded applications. Then, when the phone is synched, it will maintain its own change log since last synch and iTunes and iPhones will quickly exchange change logs and then iTunes can quickly determine what it specifically needs to do to bring the phone and itself "up to date". As far as data from the phone, such as purchased music, videos or applications, this should be uploaded FIRST and should AT WORST take 10 minutes for the raw data transfer. This constitutes part of backing up as well, so in this case the two steps may be combined. Reading data from Flash is usually very fast, so I don't see the Flash being a real bottleneck here and I think the biggest bottleneck is just the USB 2.0 interface, which is already 40 MBps, sustained. Where I would cut apple some slack is in the application / music / videos upload. Not only does the iPhone have to contend with the 40 MBps bottleneck of the upload, but the write cycle for the flash chips used by the iPhone may also cause the potential throughput to be diminished. Does anyone have specs on the flash chips used in the iPhone? What is the sector size and how slow is it to write a sector?
Anyway, all I can say is that at times like these, I really wish I worked for Apple. People would NOT be having these problems were I on the job. I develop for real-time embedded OS development all the time and I know the kind of bottlenecks that exist in devices like the iPhone. I know the ARM has its limitations, but it is a nice processor architecture. So I just don't see why this has to be so slow. It really should not be. Can someone please explain?

Answer 1

TimeHorse, I too have had this problem but I've had it before iTunes 7.7.1.11. I was just now trying to copy some new music to my iPhone and it was taking about 1-3 minutes per song. Don't even get me started into how long the backup took.
One thing I happened to notice was Windows Defender was running a scan at the same time. When I closed it, magically iTunes synching sped up drastically (3 - 4 seconds per song). This doesn't make much sense to me since my iTunes library is on a network drive, but maybe iTunes is using some swap space or temporary files or something on the local hard disk which is slowing performance due to other HD activity. You might check your disk IO when iTunes is synching, could be a bottle neck...
Anyway, just a thought