What exactly is "wipe cache partition"???

Moltres_rider

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what exactly is "wipe cache partition" is the recovery menu of the phone and what does it do??? can somebody explain wiping the cache partition and what does it benefit if I wipe it???
 

B. Diddy

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The system cache partition stores temporary system data. It's supposed to allow the system to access apps more quickly and efficiently, but sometimes things get cluttered and outdated, so a periodic cache clearing can help make the system run more smoothly. It's different from clearing individual app caches, and it won't lead to any loss of personal data or settings. Many authorities suggest a cache wipe after installing a system update.
 

paintdrinkingpete

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The system cache partition stores temporary system data. It's supposed to allow the system to access apps more quickly and efficiently, but sometimes things get cluttered and outdated, so a periodic cache clearing can help make the system run more smoothly. It's different from clearing individual app caches, and it won't lead to any loss of personal data or settings. Many authorities suggest a cache wipe after installing a system update.

Actually, what you describe more closely resembles the "dalvik cache", which is:

the /data/dalvik-cache directory that can be found on typical Android devices. When you install an application on Android, it performs some modifications and optimizations on that application's dex file (the file that contains all the dalvik bytecode for the application). It then caches the resulting odex (optimized dex) file in the /data/dalvik-cache directory, so that it doesn't have to perform the optimization process every time it loads an application.
source

or here's another similar definition:
When your phone starts up, the Dalvik Virtual Machine looks at all your apps and frameworks, and creates a tree of dependencies which is stored in the dalvik-cache. This allows applications to run in an optimised state (and explains why your phone takes longer to boot up after applying a new rom, it?s rebuilding the cache.)
Source

The only real effect of deleting the dalvik-cache (which can also be done in recovery) is that the phone will take longer to boot up, it doesn't remove any user data or settings.

Now, to answer the OP, this is different from the "cache" partion, which is:

/cache partition is mostly for saving the downloads from Google Play Store, found in /cache/downloads. It also can hold the recovery log found in /cache/recovery called last_log as well (this holds any errors and/or diagnostics from the recovery binary a la CWM or stock, which will get logged in the file to aid debugging and development of the recovery binary).

There is also another directory in there called lost+found which holds any recovered files (if any) as a result of file-system corruption, such as incorrectly removing the SDcard without un-mounting it.

So really, there is no loss of data from clearing it.

In fact, upon Android boot-up, the script will clear out the /cache/downloads to make way for any new downloads/updates from Google Play Store.
Source

So, the /cache is basically just a temp directory used by the system for downloading temporary files it needs when installing apps and such. wiping the cache partition generally will have no noticeable effect to the end user. It also doesn't really free up any space either, because it's mounted as a separate partition, and thus always uses the same amount of the total disk storage space.

Generally, if you're rooted and installing ROMs or other mods in recovery, it's always recommended to wipe both the /cache and the dalvik cache at minimum before installing anything. This is good advice and I certainly don't disagree with it, but chances are that it's actually the clearing of the dalvik that is most important.

If you're phone is running sluggish, clearing these 2 is also a quick and easy step you can take to see if rebuilding the app optimization files can improve performance.
 
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paintdrinkingpete

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Why is it good to do so after a system update???

Because it ensures that for the updated system apps, they aren't attempting to use outdated optimization files...(?).

As I mentioned above, it certainly won't hurt anything to try. To be honest, I actually feel it's best to do a FULL SYSTEM WIPE (factory reset) after installing a major update (i.e. 4.3 to 4.4), but obviously that involves having to restore all your user data and settings afterwards...so most folks don't do that.
 

B. Diddy

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Thanks for your input--I'm not an engineer, so I go by what I read, and what others experience and what I experience. I believe the dalvik cache can't be cleared in an unrooted device, correct? So wiping the cache partition from the Recovery Menu would be the other cache partition that you referenced. Perhaps it's just a placebo effect, but I've seen improvements in performance after a cache partition wipe if things were getting glitchy. Actual support sites also suggest it as a potential solution, like Motorola: https://motorola-global-portal.custhelp.com/app/answers/detail/a_id/93162/p/30,6720,8417

I've tried numerous times to get a good explanation of what is stored in the cache partition. I recall seeing the one you mentioned; also saw this one where they say, "This is the partition where Android stores frequently accessed data and app components. Wiping the cache doesn’t effect your personal data but simply gets rid of the existing data there, which gets automatically rebuilt as you continue using the device." So it sounds like it's perhaps a little more than Google Play downloads.

These are the times I wish we had an Android engineer on our staff!
 

paintdrinkingpete

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Thanks for your input--I'm not an engineer, so I go by what I read, and what others experience and what I experience. I believe the dalvik cache can't be cleared in an unrooted device, correct? So wiping the cache partition from the Recovery Menu would be the other cache partition that you referenced. Perhaps it's just a placebo effect, but I've seen improvements in performance after a cache partition wipe if things were getting glitchy. Actual support sites also suggest it as a potential solution, like Motorola: https://motorola-global-portal.custhelp.com/app/answers/detail/a_id/93162/p/30,6720,8417

I've tried numerous times to get a good explanation of what is stored in the cache partition. I recall seeing the one you mentioned; also saw this one where they say, "This is the partition where Android stores frequently accessed data and app components. Wiping the cache doesn?t effect your personal data but simply gets rid of the existing data there, which gets automatically rebuilt as you continue using the device." So it sounds like it's perhaps a little more than Google Play downloads.

These are the times I wish we had an Android engineer on our staff!

It's highly possible...to be honest, I've always been rooted and running a custom recovery, so it's hard for me to always remember what options are available in the standard recovery

To be honest, I've noticed it to, so who knows? Maybe there is more going on there...I'm certainly not an "engineer" myself, just an enthusiast. Like I said, it certainly won't hurt to wipe the /cache, so it's worth trying.

Well, that's not really different from what I was trying to get at... but think of the /cache more as a "temporary" directory that apps use. Yes, one of these uses is Play store downloads, but it's certainly not limited to that. In general that files being saved to the cache are those files which once done being used can safely be deleted, they are only needed on a temporary basis. This is different from the dalvik in that even though the dalvik can be easily rebuilt without consequence, the files placed in there are intended to be more permanent.

This is probably more info than the OP bargained for, but the "make a long story short" version of it is that clearing the cache is just a general "spring cleaning" step that can be easily done before more complex solutions need to be ruled out, as it is usually quick and painless with minimal risk. It's mainly recommended after updates just help ensure you're starting with a clean slate...whether it really makes a difference or not? On most devices it probably doesn't, but on some it may improve things.
 

elissa penn

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This may sound dumb....but what is Cache (in laymans terms) and when people "wipe" their cache, what does it do and what does it get rid of?

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B. Diddy

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It's an area where the system stores temporary data--for example, the apk installer files of apps that you choose to download and install from Google Play.
 

elissa penn

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Ok. What is APK? I don't really understand all these words, like Jelly Bean, Rooting, etc. All I know is that my phone is sluggish, I can't get a good signal or do much when my battery gets to 70% or less, which is soooo frustrating, I've lost many contacts & pics. I swear this phone has a poltergeist in it!

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** Also, I have a Motorola, RAZR, through Verizon. Gotta say, their customer service is horrible.
 

Golfdriver97

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Ok. What is APK? I don't really understand all these words, like Jelly Bean, Rooting, etc. All I know is that my phone is sluggish, I can't get a good signal or do much when my battery gets to 70% or less, which is soooo frustrating, I've lost many contacts & pics. I swear this phone has a poltergeist in it!

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Jelly bean is a code name for Android version 4.1-4.3.
Rooting is gaining ultimate access to all areas of your phone.
What device to you have?
 

elissa penn

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Sorry for the delay in responding. Can't have my phone at work, also meant to mention that it constantly says "loss of service". I used it this morning (fully charged) to play 2 games of solitaire with my morning coffee) and it did the loss of service again. I've contacted Verizon Customer Support &Motorola on multiple occasions and (obviously) have gotten nowhere. One last thing: I recently found out that mg Cloud is connected to Microsoft. I cannot remember my password for my LIVE.COM, account. I have contacted Microsoft via email and phone phone 100 times times and it's like pulling teeth to access to get a new password. Even a temporary password .. Any help would be so appreciated . As I believe my contacts are somehow connected with cloud and Microsoft office that was recently "updated and installed" on my phone. Thanks so much for ANY advice/help....I wish there was a way to receive notifications from android Central when I (anyone) receives answers to their questions.

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