By a boot of the Android OS itself looks the Dalvik (Virtual Machine) installed applications (. APKs.) Framework and files of the corresponding ROMs and builds a tree of their dependencies to the "framework" files. On this basis, the Dalvik optimized the code of applications and stores them in the Dalvik cache. (. dex). So 2 steps only tree, "unpack" and then optimize the information contained in applications. Dex files.
In ODEX-based ROMS (usually only the original Google ROMS) these optimizations are partially done already. "ODEX" files, it is split, the application sends and contained usually in the application. Dex file already is optimized apk beside the. Itself stored (. ODEX). But since this is more difficult to change, such as themes, etc, most of the FW / ROMS are not "odex'et", but "de-odexted", so really, the optimization undone. This does not affect the speed of the ROM itself, only on the first reboot this will take longer due to take the dalvik-cache these works must.
HOWEVER! the dalvik to be working in the current system (otherwise it would not be possible to install applications without a reboot of the reason stems from a myth:... Davilk works ONLY at Start-Up That is incorrect Thus: Once, either before boot, or anything in the current system (whether changes install, uninstall or deleted apps from the Dalvik is optimized and active / the respective. index deletes files in the cache.
The cache of dalvik "sits" in the User-partion of the OS (/ data). One exception is the "Memhack" This moves the Dalvik cache to the SD card to free up space in ROM memory shortage (we were only on some older phones still used as far as I know). I'm therefore "memhack" not work here.
So if you load a new Rome (for the Milestone: by flashing a "full" releases) or manually / data partion deletes (wipes) (PS: Wipe data and factory reset are 100% the same), then this cache completely removed (as part of the / data partition). Once the ROM is then booted the dalvik resumes his work, opens his Tree of dependencies, the optimized bytecode and backs it down a new dalvik cache under the previously deleted one and now newly created / data partition.
Optimize this always happens after every reboot! Manual intervention is actually NEVER necessary, because even if there are errors, they will be adjusted automatically by the dalvik, wrong. Dex files deleted etc etc.
Examples of myth:
- I wipe / data -> cache and all data gone
- I'm playing on a new ROM (full sbf) -> cache and off all data again
- I'll wait until the flash is completed, then I reboot and go into the recovery to the (delete dalvik for 3rd time I delete a data set does not exist yet.
These 3 actions to make 3 times the same.Weird,would think as a rookie, right? Correct, absolutely free of meaning and sense.
Therefore ...
- Every reboot the Dalvik cache is optimized. It is not present (our 3 examples), it is completely created (boot time is very long when the cache is created from scratch)
- In the current system works the dalvik and keeps the OS in optimal condition
- Even IF it should ever give errors (let's say I delete an APK in the recovery, or via update.zip or other (ie where all the dalvik is NOT active in the system), which takes place next reboot, and the optimized dalvik the system again without the necessity of Wiping the caches
Question:
does wiping harms the caches? No harm,he does not. But he does bring anything (except for special cases absolute). I have installed 100 determines Flashes behind me on the milestone, and certainly the 100 Nighltlies and ROMS on the Nexus. Not even I have deleted the cache or delete anything. The Android OS takes over completely without user intervention (except for absolute special cases that give its sometimes, but I have not even seen)
ITS NOT FROM ME,I HAVE ONLY TRANSLATED WITH GOOGLE!!!!
http://www.android-hilfe.de/2645790-post2.html
original link
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Upon booting up via Vol. Down + Power, there are four options (fastboot, recovery, wipe cache, and simunlock). What happens when you wipe cache?
I just installed a new ROM (well updated), couldnt get it to boot as I was stuck on the custom boot screen, but after wipe cache it loads up?
Does this effect the functionality at all? Please help. Thanks
I believe this is a factory wipe, but is a dumbed down version, that does not wipe /sd-ext partitions etc. Just removes /data programs and user info, but won't touch any /system applications.
It is used to reset the phone without actually booting up the OS
Any particular reason why my ROM wouldnt boot up normally but requires a cache wipe in order to boot?
trenwei said:
Any particular reason why my ROM wouldnt boot up normally but requires a cache wipe in order to boot?
Click to expand...
Click to collapse
Soms roms will require you to wipe dalvik cache in order for the new rom to boot (conflicts can be caused), and wiping this cache would do it, however you can just wipe dalvik cache from recovery not this hboot menu.
For future reference when changing roms, especially when changing to someone elses rom (and especially especially when its a different base) you should be doing a full wipe
A full wipe is:
-Data (factory reset)
-Dalvik Cache
-Ext partition (although sometimes you can get away with skipping this one)
You should be able to wipe those three from both Amon-RA and Clockwork Mod recoveries.
NOTE: I am sleep deprived, so this will proberly not make alot of sense
I'm not that technical with the Android system (have worked with linux abit though)
Deleting the cache would remove any saved data from the system. These saved items may contain anything from images to which default program is loaded, to which widgets are loaded on the homscreen.
This is why after a new install the phone takes a little longer booting up, creating all the new files. If you need me to go into cache, use Google.
Another theory would be:
After an upgrade, some files and apps think that the system has changed owners, so their permissions change from read/write to read/only etc.
With this, some system files will become inaccessible, will be unable to be edited and so forth.
A way around this would be to "fix" the permissions of the data, changing the owner of the files allowing read/write permissions
Rom Manager has a nice little feature that allows you to fix permissions, and has come very helpful for me, with my switching to and from OD/Pinky, and restoring LauncherPro, which likes to FC at every restore -.-.
I'm using mero's wiping tool before flashing a new version of Revolution HD.
But I'm wondering if it's really necessary, at least the Easy-Update 1.0 version. What it does is:
Will format(wipe) the following:
* BOOT
* SYSTEM
* CACHE
Click to expand...
Click to collapse
The 1.3 full wipe doesn't wipe BOOT anymore because it's completely rewritten anyway. Why is it needed with Easy-Update?
About SYSTEM. When flashing a new ROM it says "formatting partitions". I *guess* that's the system partition, so then wiping it wouldn't be necessary?
And the CACHE partition, does it really need to be wiped? I'd think that the OS manages this partition so that when there are cache files from an app that's now gone due to flashing it will delete them.
So if I don't want to loose my DATA partition do I really need to wipe BOOT/SYSTEM/CACHE?
And now the next part of my question...
I guess when flashing so often it's good to once in a while wipe DATA as well. Though I'm a bit reluctant about this as well since Android was created with people in mind who are uninstalling/installing apps every day so DATA shouldn't litter easily.
Anyway, when I decide to wipe it, I want to keep some of the data. For example games or apps that have considerable customization or save data.
For that I use Titanium Backup. Now I'm wondering if I restore some of my apps incl data, that will partly contradict the wiping. So what's the use wiping DATA then, removing data of apps that are gone due to flashing?
Just curious is it normal for android 5.0 to use so much dalvik cache mine is about 450mb I used titanium backup clear dalvik cache after restart android optimizing again at boot up.
TiBu seems to have been abandoned by the developer, I just tried to email them about not being able to write to my external SD card and it was returned as a bad address. If it is still in active development, it's not ready for Lollipop yet. It told me my dalvik cache is loaded with over 300MB of unnecessary files, but I know that isn't true.
Thanks, unable to write SD card has to do with android is not with TiBu you need to find way to enable SD card writibility. Not only TiBu shows dalvik cache loaded over 450mb I'm able find the folder with root explorer in my system it lol like user apps are associated in dalvik cache.
Yeah. I used es file Explorer to try to write to SD and it opened a file manager from lollipop and said to unhide the SD card so I did and now I can write to it.
MadJoe said:
TiBu seems to have been abandoned by the developer, I just tried to email them about not being able to write to my external SD card and it was returned as a bad address. If it is still in active development, it's not ready for Lollipop yet. It told me my dalvik cache is loaded with over 300MB of unnecessary files, but I know that isn't true.
Click to expand...
Click to collapse
Lollipop did not totally abandon dalvik cache. All it did it is to write pre compiled files to dalvik folder when installing while back in KitKat the system did not compile apps during installation but compile them just before them run (JIT). If you somehow delete/cleared all/some cached dalvik files in lollipop, system will try to re-compile the corresponding app so that you don't have to compile before they run.
Whenever an app updates via google play system compiles it during installation. However, when apps are updated via system update (Odin, ZIP flashing, OTA,you name it) , system will recompile the new apps which is why the first boot of lollipop takes so much time ( It is compiling all upgraded app!!).
Because TiBackup does not compile apps when restoring them, when you try to run the restored app, lollipop will try to find the pre-compiled file under dalvik cache directory but the correct one is not there. Therefore the app will not run properly. This is why after TiBackup restore in lollipop, always clear dalvik cache and cache and reboot. The restored app will be compiled correctly after during rebooting~ The same applies to Zip/Odin flashing too.
Was I not supposed to wipe the cache and/or ART cache in TWRP? Because, to try and fix a stupid problem, I did wiped that and created a lot of other problems. STUPID!
Facebook/Messenger keep force closing when opened...
Amplify also keeps force closing when opened...
Xposed no longer works, it says it's installed and active but it does nothing. Tells me to check the log, but there is no error file (it can't create the file).
I get a 404 error when Xposed tries to download the modules list.
I made a System + Data + Boot backup but I've read that since "Data" is encrypted on the HTC 10 with proprietary algorithms, that it's not possible to restore it. I could just restore "System" and "Boot", but will that do anything? And shouldn't I clear Cache and ART Cache after doing that anyway?
What the hell did I do to my phone? Save
I might have fixed this...
I just uninstalled a bunch of root apps (AdAway, Xposed, SuperSU, Greenify), apps that change the "system" (although they were systemless) and restored my boot image. Cleared Cache and ART Cache again, rebooted and reinstalled Facebook/Messenger. They are now working again
I'm going to reinstall everything else back, one by one and see if everything is fixed...
Everything seems to be fixed
I looked through many threads, posts, websites, and tutorials, but none of them say how to literally wipe my device completely (it could be that it's not possible), what I want to do is completely remove literally everything so that it's like a brand new hard drive without even any files in it.
'Factory Reset' doesn't remove everything because android still boots after a factory reset and android wouldn't be able to boot if there were no files on the device. TWRP doesn't remove everything either because how is twrp running, and I can still see the androids root directories in twrps file manager (TWRP does tell me that there's no OS installed, but then why is there still a functioning file system with actual files in them).
I want to completely wipe everything so that any future roms I download will have no way to be affected by any old kernels/roms/apps that I have installed in the past. I want to clean install android on top of a literally empty phone hard drive. If this isn't possible then what's the closest to that that I can get? Cuz I tried various roms and I had bugs that persisted between multiple roms even though other people said that they didn't have these issues.
In case you're wondering: I'm currently running LineageOS 15.1, oreo 8.1
Your best bet it to wipe using stock image. Reinstall TWRP and wipe system, cache and data before installing new ROM
I agree with the advice given by Vanschtezla.
Also, if you would completely wipe all data on the phone's storage then that would also wipe the partition table. The storage area is divided into partitions which are mounted to for example /system /data and /cache when your phone boots.
Also there is no real need to "wipe everything" as you say as that could brick your phone. If you just boot TWRP and wipe using "Factory reset" and additionally: System then everything should be clean enough to install a new ROM. Depending on the ROM it will wipe the System partition anyway.
Kernels reside in the system partition so when you wipe System, any Kernel is gone
Pre installed (system) Apps sit in the System partition so wipe System and they are gone
User Apps sit in the data partition so wipe data (that is included in the Factory reset) and they're gone
All in all I think you're expecting issues that simply do not exist. Especially if you just follow the instructions of the (custom) ROM you want to install.
THANK YOU!
peterpv said:
I agree with the advice given by Vanschtezla.
Kernels reside in the system partition so when you wipe System, any Kernel is gone
Pre installed (system) Apps sit in the System partition so wipe System and they are gone
User Apps sit in the data partition so wipe data (that is included in the Factory reset) and they're gone
Click to expand...
Click to collapse
This is exactly what I was looking for! Why don't any "How to wipe your phone" guides say these things (even the ones that get more technical don't mention what exactly gets deleted for each wipe option, which is why from your perspective it was probably very weird to read my question).