about app2SD


This be the most common method used. In Froyo actually install. Apk can already stored on the SD card, with notes on applications that are installed on the SD card storage support. The transfer was done manually by going to the application App2SD. but there are also applications that will remain stored in internal memory.

App2SD + Move2SD Enabler  (tutorial how to use here)

The next method if using application App2SD (need root access) inadequate (less internal memory). we will use Move2SD Enabler for each installation. apk can be set automatically in order to move all to the SD memory card (External). So applications that previously could not be transferred to the SD card because it does not yet support the storage to the SD, could be moved even though there are few applications that really make a rule can not be moved (PHONE ONLY). This method can save the use of internal memory. there is a shortage of this method, if we connect to a PC using USB Storage mode, then the application is moved to SD, can not run (Force Close).

Virtual Memory (tutorial how to use here)

This method is used if it were less satisfied with the results App2SD, and Move2SD Enabler. This method is actually similar to App2SD + Move2SD Enabler, only the applications and data stored on the ext2 partition that was made before. Almost all. Apk and its data will be stored in the ext2 partition, since this partition will be read as the internal memory by your android device. So although later connected to a PC using USB Storage mode, applications that have entered the ext2, will keep running.

JIT Compiler

Before the official Froyo announcement at I/O, we’d learned that an Adobe employee’s phone was running at ridiculously high speeds. Most outlets quickly chalked this up to the possibility that Google implemented a Just-In-Time compiler for their Dalvik Virtual Machine.
Sure enough, they confirmed our suspicions at the keynote in San Francisco, and we even got a taste of real-world performance (there’s no “theoretical” performance hikes here, folks). We know what JIT does, but I’m sure there are a lot of non-developers out there that can’t understand how it’s able to provide the huge bump in performance for Dalvik.

Technical lead for Android’s Dalvik team – Dan Bornstein – signed in with a blog post over at the Android developers site going into a bit more details about what’s really going on beneath the hood to significantly improve performance of Android (in certain cases) without needing to touch the hardware. Thankfully, he puts it in plain English so you can get – at the least – a pretty basic understanding of what’s going on. Head over there now if you want to learn more about what makes your Froyo so sweet.


What is SWAP?
Swap space is an auxiliary storage, such as a portion of a hard-disk, which can be used as memory by the operating system when system RAM is insufficient. This is especially useful on systems with very little system RAM, such as most DD-WRT compatible routers, as it helps prevent the system from running out of memory when multiple background processes are installed.

The difference between Froyo A2SD, A2SD and A2SD+

One of the glories of using Android is having an SD card for storage rather than having internal-only memory. Thanks to Android’s Linux blood, you can even harness the power of the SD card beyond its usual file storage capabilities. On Android, your internal memory is precious and you do not want to install games and applications – especially those which are up to 50MB in sizes – on your internal memory just to make your phone run slower. Instead, you can install the applications on SD card and let your phone take care of the system apps instead, saving more internal memory and speeding up your phone.

The Partitions

Android natively supports fat32 partition. However, thanks to the Android community, support for swap and ext partitions can be enabled too. Depending on the ROM, some can support up to ext4, while others support up to ext3. The explanation about the differences between these partitions is indeed very lengthy and not part of our chapter today. What is important to know, is that Android has support for fat32, swap, ext2, ext3, and ext4 partition support.

Your SD card is by default formatted to fat32. In order to use swap and ext partitions, you need to repartition your SD card. There are several ways to do this, but the most common way is by using a custom recovery installed on your phone (ClockworkMod or AmonRA recovery). Swap is virtual memory which uses extra space on your SD card for virtual memory. However, since Android already has DalvikVM, swap is not really needed. I myself don’t use swap space on my SD partitions. Ext partition is extended partition which was the first ever type of partition created specifically for Linux. It is based of the standard UNIX file system and was designed to overcome the limitations of Minix file systems. Ext 2 is second extended partition, ext3 is third extended partition and ext4 is the fourth extended partition respectively.

Dalvik Virtual Machine

One of the best functions of Android has to be the Dalvik cache. Dalvik cache is a wonder from the point your Android starts up, runs, hibernates and all the way till you device shuts down. Dalvik cache collects the information about the installed applications and frameworks, and organizes them into a writeable cache. Under this writeable cache, it stores the “optimized” bytecode of the applications which is used by the applications themselves later for a smoother operation. This dalvik cache can grow immensely huge as more applications are installed on your phone. It is safe to wipe dalvik-cache. It will be rebuilt again when the phone boots. This also explains why your phone takes ages to start up for the first time. As for my Nexus One, having about 145 applications installed, it takes about 13 minutes to build the cache.

If you ever extract an APK installer file, you will always find a file named classes.dex. This is the file Dalvik finds to build the cache. What makes the process slow? APK is an archive (which is why you can open it up with an unarchiver such as WinRAR or 7-Zip). Being an archive, it provides limited write access to the files contained within and the fact that archives are compressed. Not to forget, APKs are encrypted archives too. Therefore, DalvikVM has to extract the classes.dex files and build the Dalvik table accordingly which makes it easier to write data on it too. With this collective set of data, the Android OS no longer needs to index the applications and find their classes.dex when the phone is already running. Instead, it will just look into one place, and will know what to do next. Nifty huh?

To know what is going on inside the Dalvik VM, you can read about it here.

Froyo A2SD (F-A2SD)

When Froyo was released to Android community, one of its new features was the A2SD implementation. F-A2SD uses fat32 partition natively for application storage. This means, all you have to do is just slot in your SD card and its all ready to go. There is no need to partition the SD card whatsoever. This was a great effort from Google to include A2SD to the Android OS as it gives you an option to choose which applications you want to move to SD card, and which you want to leave on internal memory – BUT – with a condition! If the application developer decides to protect his application and not include A2SD support, you would not be able to move it to SD card. One major problem that F-A2SD has is that it only uses fat32 partition. This way, when the SD card is mounted to the computer, the applications become inaccessible. Not only that, if the applications have widget support, the widgets are removed too when the SD card is mounted. This can become rather a hassle especially if you have to mount your computer several times in a day.


The A2SD method is much more interesting. It harnesses the glory of ext partitions. This way, the applications (protected or non-protected), will all be installed on the SD card ext partition. The good thing about ext partition is that when you mount your SD card, the ext partition is NOT mounted together. This said, when your SD card is mounted, the applications will still be accessible and separated from the files and folders on your fat32 partition. On A2SD, the dalvik cache resides on the phone memory.


A2SD+ takes the A2SD one step further. Its pretty useless to have a 512MB A2SD capacity if your dalvik cache is still on phone memory and you have lots of applications installed. This is because the dalvik cache can become pretty huge and just by using HALF of your A2SD’s ext partition, your internal memory can become FULL because of dalvik. Therefore, in A2SD+, the dalvik cache is also moved to SD card. This way, your internal memory is free as a highway. However, remember that Dalvik cache is accessed very frequently. If you have a slow SD card, the overall performance might be affected. I recommend using a class 6 or class 10 SD card for the purpose.

Extreme App2SD / virtual memory A2SD + (tutorial how to use here)

This is the most extreme methods for all installations. Apk, Dalvik-cache, data system & app folder will be moved all the ext2 partition. SD cards are very risky if you are still low speed, because the device will capture all process of the SD card.

note :
If you use virtual memory, app2SD and move2SD enabler, it will take some internal memory, because most of the data for fixed applications installed into the internal memory. we can be sure that: INTERNAL memory will be reduced. If you want all applications into external memory, must use extreme app2SD script. With the consequences of many complaints when the application is installed then the performance of your Android device will be much reduced.


cipcip said…
i did all the rooting and now the program move2sd enabler is not oprnig the page with auto, internal and external selection butons, i had uninstaled and instaled again the program and it stil dose that, what to do now?
gumbung said…
just go to setting, manage application, search app2sd, then select and touch the icon about 5 second. then clear data. done.
gumbung said…
sorry app2sd, mean move2sd enabler. even you uninstalling it, the save data still not removing. this metode usefull for all application.

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