These instructions assume your phone has been unlocked/rooted, if not you should use the cyanogenmod windows installer to do the work for you.
The current ROM I am using is cm-11-20141230-NIGHTLY-i9100 on my Samsung Galaxy S2 i9100 (intl) from http://download.cyanogenmod.org/?device=i9100 and I used GApps from http://slimroms.net/index.php/downloads/dlsearch/viewcategory/1150-addons4-4 - I used the Slim_mini_gapps.4.4.4.build.8.x-385 og
When you install a ROM
When install a ROM it just replaces the /system/ partition (and cyanogen it also does the /boot/ partition) thus all system settings are saved which are stored in /data/
Wiping the system Partition
Does the following
- seems to do nothing in the sense of when you re-install your ROM, all settings are maintained
- you need to reconnect your google account, possibly android keeps google account info in the /system/ partition
Notes
- Format /System Question | T-Mobile Samsung Galaxy S II SGH-T989 | XDA Forums – useful re-assurancew that wiping the system partition does not wipe your data (which it does not)
General Installation Notes
- How to Install CyanogenMod on the Samsung Galaxy S II ("i9100") - CyanogenMod – original instructions
- Android 4.4.4 CyanogenMod 11 M8 Stable Release Arrives for Galaxy S2 I9100/I9100G – with installation instructions
- What Is A Nandroid Backup and How Exactly Does It Work?
- How To Make A Nandroid Backup Of Your Android Phone
- Install CyanogenMod 11 M9 Android 4.4.4 Stable ROM for Samsung Galaxy S4 LTE (GT-I9505)
- CyanogenMod 11 Nightly Android 4.4.4 KitKat Arrives for Galaxy S2 I9100 and I9100G
- How to enter Recovery Mode in Samsung Galaxy S2 by AndroidADN - YouTube
CM 11 ROM Notes
- Nightly 20140212 - Unfortunately Trebuchet Has Stopped - Google Nexus 10 Development - CyanogenMod Forum
- Trebuchet is the Home Screen by Cyanogenmod
Other Notes
- How to boot into custom recovery (like CWM or TWRP) on Android
- How to boot into bootloader (HBOOT) | Android Forums
Android 5.1.1 on Samsung S2 Links