This I'm sure you're already aware of: when you install a custom ROM, like CyanogenMod for example, you'll read from many different sources that you should perform a wipe beforehand. And although there are also other voices that time and time again suggest something else, a wipe is always a must!
When conducting a wipe, partitions of the internal memory space are emptied. Depending on what wipe you chose, your downloaded apps, as well as personal and system settings will be lost. Pre-installed System apps will always be reset to the original state. After a complete wipe, your smartphone will behave just as if you were acquiring it for the first time from the store.
Theses are the trendiest wipe methods, from which you can chose, depending on the recovery you've used:
- Wipe data/Factory reset: In this case all of your personal data will be deleted and your system will be returned to its original state.
- Wipe Cache Partition: Here the cache will be deleted. You'll usually find a lot of used data in the cache, which serves as a buffer for quicker access. Personal data, however, isn't lost with this method.
- Wipe Dalvik Cache: All programs are saved within a directory tree in the Dalvik cache. Furthermore, you can transfer your storage addresses and partitions here. This is particularly advantageous in the case of memory-hungry apps. This also keeps your personal data from being deleted after the wipe.
The recovery type ClockworkMod Recovery with various wipe options
Why wipe and which wipe is for what?
Without performing a pre-emptive wipe after the installation of a new ROM, all of the contaminated areas remain from the previous installed system. This is exactly what often leads to problems, crashes and unstable systems. For this reason is a wipe always recommended!
When you switch your ROM, for example from the CyanogenMod stock, you should absolutely execute the option ''Wipe Data'' before going any further. This way the complete system will be cleaned out and you can properly install your custom ROM, without any backlogs or contaminated areas.
In the case of smaller ROM updates, for example something between CyanogonMod 9.0 and CyanogenMod 9.1 or when installing a new Nightly, it suffices when you implement the options ''Wipe Cache Partition'' and ''Wipe Dalvik Cache''.
When it comes to bigger ROM updates, like something between CyanogenMod 9 and CyanogenMod 10, you should always play it safe and conduct ''Wipe data'' again. As a general rule it is sufficient namely when you only empty the cache and the Dalvik-cache. However, I know from my own experience and from other people's accounts that it's actually better to make a bit of an effort in advance than to struggle later with errors and crashes.
Within the advanced menu you will find further options, like ''fix permissions''
A wipe helps with many problems related to custom ROMS. If after performing an installation and you run into errors, crashes and even problems with bootstraps, a wipe helps out in a quick and easy way and whips your smartphone or pad back into shape. If you still encounter problems even after a wipe, then conduct the option ''Fix permissions'' during the recovery as well. This way all the app and system data writing and reading permissions will be correctly set. Afterwards, it's often the case that errors are a thing of the past.
(photos by Nico Heister/AndroidPIT)