[Nexus S General] distortedloop:
[GUIDE] Root & recovery WITHOUT oem unlock & wipe (2.3.2 & older, plus now 2.3)

UPDATE #2 - Fitchman has reported successful root and rom flash without unlocking the bootloader by using Ginger Break. Full details in this post: http://xdaforums.com/showpost.php?p=13236136&postcount=135

UPDATE - IMPORTANT: This method does not work with Android 2.3.3. Search the forum or this post in this thread for a way to update to 2.3.3 and root without unlocking if you haven't updated yet.

Alternatively, use this method on 2.3.2 and lower, then use titanium to back up everything, store it on your laptop (along with all your sdcard's data), then do the oem unlock step first and then continue from there with the rest of the guide.

Not my original idea, but a consolidation of a discussion between inakipaz and shrivelfig and myself in another thread and being posted here for easier finding by future root-seekers.

Shrivelfig's tested the method to re-root a previously rooted pone with a re-locked bootloader, and inakipaz has done it on a phone that's never had the bootloader unlocked.

The advantage here is that those who chose not to root when they first got the phone won't lose any app data or sdcard data like the methods that have you unlock the bootloader do. The disadvantage is your bootloader remains locked, which may prevent you flashing certain things in the future.

edit: see ravidavi's posts below; he's shown you can even flash custom roms that are clockwork compatible while having a locked bootloader with this method.

Download these two files:

clockwork recovery v3.0.0.5 or clockwork recovery v3.0.0.5 mirror if above not working

su-2.3.6.1-ef-signed.zip

Koush's blog for the latest clockwork updates (find Nexus S in the list).

Also, if you don't already have the necessary android sdk and drivers on your computer, get them from here: http://developer.android.com/sdk/index.html and install them. Some Windows users report better luck just installing pdanet. There's a decent guide for Windows users on installing the sdk here.

Place the recovery file on your laptop where you can access it while using the sdk fastboot commands.

Place the su zip one in the top level folder of your sdcard.

Put your phone in fastboot mode (power off, then hold volume up and power key at the same time until the phone boots to a white screen).

Use fastboot to boot the phone into the clockwork recovery:

fastboot boot recovery-clockwork-3.0.0.5-crespo.img

If you're not sure how to get fastboot working on your computer, follow the excellent instructions that Allgamer gives in this GUIDE, but don't do the oem unlock command!

Once in clockwork, flash the su file to the phone by following these steps below.

To navigate in the clockwork recovery, you use the volume keys to scroll up/down through the menus, and the on/off button to select what's highlighted.

(note: some report success without these first 3 steps, others don't get a succesful root without, I recommend doing them)

select mounts and storage.

select mount /system

select go back

select install ZIP from sdcard

select choose zip from sdcard

select su-version#-signed.zip file you downloaded earlier

select yes - install su-version#-signed.zip

confirm it says "Install from sdcard complete"

select go back

select reboot

After the phone reboots, you should be rooted, with a locked bootloader, and none of your data erased.

That said, never hurts to have a backup of your precious data on the sdcard that you can copy over to the computer.

This method doesn't install busybox, so go to the Market and download/install busybox directly, or get Titanium Backup and check it's "problems?" button and let it install busybox for you. There's also an app called root checker that supposedly verifies you have a working root on your phone.

Once you have a successful root installed, I'd suggest getting back into clockwork recovery and running a nandroid back up from clockwork's backs and restore menu. Then copy that file from your sdcard (in the /clockwork/backups folder) to your laptop for safe-keeping and an easy full system restore to a known working config.

Usual disclaimers about I'm not responsible for damage to your phone or loss of data apply. Use any rooting method at your own risk.

Thanks and all the real credit go to inakipaz, shrivelfig and allgamer, and of course to koush, and ChainsDD for the superuser apk.