Root wipe cache vs wipe Dalvic Cache

[RunVert]

I always wipe my Dalvic cache in recovery....how is that different than choosing just the wipe cache option?

 

[Granite1]

I always wipe my Dalvic cache in recovery....how is that different than choosing just the wipe cache option?

I believe wiping cache partition and wiping Dalvik cache is actually wiping two different caches. So wiping the cache partition wouldn't include the dalvik cache.

I'm not 100% sure, so If I'm off mark, someone please chime in.

 

[evomattnc]

I believe wiping cache partition and wiping Dalvik cache is actually wiping two different caches. So wiping the cache partition wouldn't include the dalvik cache.

I'm not 100% sure, so If I'm off mark, someone please chime in.

You are right. Dalvik for some reason I don't agree with is usually in /data unless you have moved it. I don't think it should take up your data space but whatever...

 

[akazabam]

If you think about what dalvik cache does, it sort of (from a logical standpoint) makes sense to put it in /data. It's basically for optimization. It has to do with dependencies used by apps when executed. Since it's directly correlated with what you're running off /data, it kind of makes sense. The problem is that it doesn't makes sense from the user's point of view, being limited in the amount of space on /data. Cache (not dalvik cache) is used for a completely different purpose. It has its own partition because it uses it as a temporary holding place for downloads. When you download apps from the market, this is where they go before installation. It's as big as it is because it's also where OTA downloads go before installation. These can be quite large, so this is a nice holding place for them. It's also use for a few other random things, such as sending instructions to recovery. Ever wonder how front-end apps that run in Android can reboot the phone into recovery and have it do whatever you told it to do while still booted up? It's generally through instructions written to files that are then stored in /cache, where recovery can then read them and remove them when done.

In any case, once you have root, it's generally assumed you won't be downloading any OTAs any time soon, so you really don't need all 160 MB of space dedicated for that. So, if you use a2sd (or you technically could do it all yourself from the command line, manually), you can move this dalvik cache from /data to /cache. You can also move it to the sdcard, but if you remember what I said about its purpose above, you can imagine that it will slow things down unless you have a fast card.

All that being said, if you keep your dalvik cache where it is in /data, when you do a data wipe (like if you're going to flash a ROM, for example), it will be wiped as a part of that. If you keep in /cache, it will be wiped when you wipe cache. It's more or less a formality to wipe it in this case, just to make sure it's really gone. If you're not doing a data wipe (like if you're flashing a kernel, for example), and you haven't moved dalvik cache anywhere, you'd need to wipe it, as nothing else will do it. If you keep dalvik cache on the sdcard, then you definitely need to wipe it every time you're doing something that wipes dalvik cache (unless you wipe sdext).

 

[9to5cynic]

I could be wrong, but isn't Dalvik the VM that android runs? So Dalvik cache would be related to that, while I'm guessing cache is just a normal run of the mill cache. There should be some advanced documentation out there... Come on Sprint! Get with the program! lol.

 

[akazabam]

I could be wrong, but isn't Dalvik the VM that android runs? So Dalvik cache would be related to that, while I'm guessing cache is just a normal run of the mill cache. There should be some advanced documentation out there... Come on Sprint! Get with the program! lol.

Yeah, basically. There are sort of three kinds of cache. The dalvik cache that we've been talking about, regular cache for downloads and a few other random things, and app cache. App cache is almost always kept in /data/data with app data for a specific app. This is why you sometimes see random fluctuations in free space on /data.

 

[RunVert]

If you think about what dalvik cache does, it sort of (from a logical standpoint) makes sense to put it in /data. It's basically for optimization. It has to do with dependencies used by apps when executed. Since it's directly correlated with what you're running off /data, it kind of makes sense. The problem is that it doesn't makes sense from the user's point of view, being limited in the amount of space on /data. Cache (not dalvik cache) is used for a completely different purpose. It has its own partition because it uses it as a temporary holding place for downloads. When you download apps from the market, this is where they go before installation. It's as big as it is because it's also where OTA downloads go before installation. These can be quite large, so this is a nice holding place for them. It's also use for a few other random things, such as sending instructions to recovery. Ever wonder how front-end apps that run in Android can reboot the phone into recovery and have it do whatever you told it to do while still booted up? It's generally through instructions written to files that are then stored in /cache, where recovery can then read them and remove them when done.

In any case, once you have root, it's generally assumed you won't be downloading any OTAs any time soon, so you really don't need all 160 MB of space dedicated for that. So, if you use a2sd (or you technically could do it all yourself from the command line, manually), you can move this dalvik cache from /data to /cache. You can also move it to the sdcard, but if you remember what I said about its purpose above, you can imagine that it will slow things down unless you have a fast card.

All that being said, if you keep your dalvik cache where it is in /data, when you do a data wipe (like if you're going to flash a ROM, for example), it will be wiped as a part of that. If you keep in /cache, it will be wiped when you wipe cache. It's more or less a formality to wipe it in this case, just to make sure it's really gone. If you're not doing a data wipe (like if you're flashing a kernel, for example), and you haven't moved dalvik cache anywhere, you'd need to wipe it, as nothing else will do it. If you keep dalvik cache on the sdcard, then you definitely need to wipe it every time you're doing something that wipes dalvik cache (unless you wipe sdext).

So I recently moved my dalvic cache to /cache. So am I correct in saying, when I want to wipe my dalvic cache I now need to wipe cache in order to achieve this....and not wipe dalvic cache. (when flashing ROM's...etc)
If this is correct, then is there any need for me to choose the wipe dalvic cache option in recovery anymore?

 

[akazabam]

So I recently moved my dalvic cache to /cache. So am I correct in saying, when I want to wipe my dalvic cache I now need to wipe cache in order to achieve this....and not wipe dalvic cache. (when flashing ROM's...etc)
If this is correct, then is there any need for me to choose the wipe dalvic cache option in recovery anymore?

Well, Amon RA recovery, I know for a fact, is smart enough to attempt to wipe dalvik cache in either of the three places it could possibly be in (/cache, /data, or /sd-ext). I don't know about CW, but I would assume it's smart enough to do the same. That being said, it can't hurt specifically wipe it, but if you have moved it to /cache, it will get wiped when you wipe cache.