I had been wanting to jailbreak my iPhone 4 for quite awhile but since I had upgraded to Apple iOS release 4.2.1 there was not an untethered jailbreak available at the time and since I typically turn my iPhone completely off I didn’t want to deal with the untethered jailbreak. So needless to say when GreenPois0n rc5 was released I was pretty excited. GreenPois0n rc5 made it extremely easy to jailbreak iPhone’s running iOS 4.2.1. After running it for around a month now though I noticed that I really don’t install enough applications outside of what is available via the iTunes App Store to warrant the jailbreak and especially because I have personally noticed that with my iPhone jailbroken it had slowed down a bit. Not only had it slowed down but my battery appeared to be draining much quicker which I assume was from more processes running. I made the decision a couple days ago to roll back to the stock iPhone 4.2.1 firmware to see if my phone started running more efficiently. Below are instructions for rolling back the GreenPois0n firmware on an iPhone 4 to the Apple iOS 4.2.1 firmware release.
First of I would like to say that none of these hacks and files are my own work. This stuff was done by all the amazing phone developers over at XDA Developers. I am am simply writing a few posts on rooting the HTC Evo since most of the information was all spread out over the forums and I had a hard time gathering it all together in a organized manner.
As you may have guessed rooting your Evo voids the warranty. If you have to have your phone serviced for any reason you will need to get back to a stock rom.
There are two ways to do this which I will outline below:
I had a customers computer in the store today which was a simple windows XP home edition desktop and they wanted to restore the PC to a earlier time. This is normally a simple task however when I went to system restore I recieved the error “System Restore Disabled by Group policy”. Since this was just a normal persons desktop I found this very odd. Next I tried to edit the policy values via the registry and was greeted by another error saying ” Registry Editing has been Disabled by Group policy”. This was starting to get a little annoying so I decided to document my steps to fix this issue. Now before I get a hundred comments with people saying there is a better way remember there is more than one way to do things and this is just my way.
Below I document the few simple steps to fix this error.
I have been needing to upgrade the PostgreSQL servers at my work for awhile now and was finally forced to do so after needing some of the features available with PostgreSQL 8.4.X. Currently we are running PostgreSQL 8.3.10 which is super old but it is definitely not the latest stable release available. One thing I am looking forward to testing is the improvements to the vacuum process. Over the past two years I have become a lot more familiar with Postgres and one thing that has been disappointing is the downtime involved in reclaiming disk space via data removed from PSQL database tables. The full vacuum process, which is required to reclaim disk after deleting data from a table, in 8.3 requires a lock on tables which essentially causes downtime. When you are dealing with large tables over 10GB in size this can take days to complete. Follow the directions below to first backup all of your PostgreSQL data, remove the current PostgreSQL installation, and then install PostgreSQL 8.4 on a CentOS Linux server.
If you are in process of downgrading your iPhone or iPod Touch you will more than likely be downloading the older firmware directly from apple.com. When you download this firmware it is provided as a zip file with a .zip file ending such as iPhone2,1_3.1_7C144_Restore.zip. If you unpack this file it will include a couple directories and numerous files as listed below.