Android Partitions Explained: boot, system, recovery, data, cache & misc

Unless you have been using your Android phone just for calls, SMS, browsing and basic apps, you should know that Android uses several partitions to organize files and folders on the device. Each of these partitions has a distinct role in the functionality of the device, but not many Android users know the significance of each partition and its contents. In this guide, we will take you on a tour of Android partitions, what they contain and what can be the possible consequences of modifying their content.

Android Partitions

Let’s start with a list of standard internal memory partitions on Android phones and tablets. These are:

  • /boot
  • /system
  • /recovery
  • /data
  • /cache
  • /misc

In addition, there are the SD card partitions.

  • /sdcard
  • /sd-ext

Note that only /sdcard is found in all Android devices and the rest are present only in select devices. Let’s now take a look at the purpose and contents of each of these partitions.

/boot

This is the partition that enables the phone to boot, as the name suggests. It includes the kernel and the ramdisk. Without this partition, the device will simply not be able to boot. Wiping this partition from recovery should only be done if absolutely required and once done, the device must NOT be rebooted before installing a new one, which can be done by installing a ROM that includes a /boot partition.

/system

This partition basically contains the entire operating system, other than the kernel and the ramdisk. This includes the Android user interface as well as all the system applications that come pre-installed on the device. Wiping this partition will remove Android from the device without rendering it unbootable, and you will still be able to put the phone into recovery or bootloader mode to install a new ROM.

/recovery

The recovery partition can be considered as an alternative boot partition that lets you boot the device into a recovery console for performing advanced recovery and maintenance operations on it. To learn more about this partition and its contents, see the ‘About Android Recovery’ section of our guide to ClockworkMod recovery.


/data

Also called userdata, the data partition contains the user’s data – this is where your contacts, messages, settings and apps that you have installed go. Wiping this partition essentially performs a factory reset on your device, restoring it to the way it was when you first booted it, or the way it was after the last official or custom ROM installation. When you perform a wipe data/factory reset from recovery, it is this partition that you are wiping.

/cache

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.

/misc

This partition contains miscellaneous system settings in form of on/off switches. These settings may include CID (Carrier or Region ID), USB configuration and certain hardware settings etc. This is an important partition and if it is corrupt or missing, several of the device’s features will will not function normally.

/sdcard

This is not a partition on the internal memory of the device but rather the SD card. In terms of usage, this is your storage space to use as you see fit, to store your media, documents, ROMs etc. on it. Wiping it is perfectly safe as long as you backup all the data you require from it, to your computer first. Though several user-installed apps save their data and settings on the SD card and wiping this partition will make you lose all that data.

On devices with both an internal and an external SD card – devices like the Samsung Galaxy S and several tablets – the /sdcard partition is always used to refer to the internal SD card. For the external SD card – if present – an alternative partition is used, which differs from device to device. In case of Samsung Galaxy S series devices, it is /sdcard/sd while in many other devices, it is /sdcard2. Unlike /sdcard, no system or app data whatsoever is stored automatically on this external SD card and everything present on it has been added there by the user. You can safely wipe it after backing up any data from it that you need to save.

/sd-ext

This is not a standard Android partition, but has become popular in the custom ROM scene. It is basically an additional partition on your SD card that acts as the /data partition when used with certain ROMs that have special features called APP2SD+ or data2ext enabled. It is especially useful on devices with little internal memory allotted to the /data partition. Thus, users who want to install more programs than the internal memory allows can make this partition and use it with a custom ROM that supports this feature, to get additional storage for installing their apps. Wiping this partition is essentially the same as wiping the /data partition – you lose your contacts, SMS, market apps and settings.

With this, we conclude our tour of Android partitions. Now whenever you install a ROM or mod that requires you to wipe certain partitions before the installation, you should be in a better position to know what you’re losing and what not and thus, you’ll know what to backup and what not.

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  • Grateful

    Great introduction. Thanks so much!

  • ajrk007

    Hi,
    It was very nice introduction to android partition. Thank you.
    However, I have a little out of the way question. I’m using Samsung Galaxy Pro (GTB7510) with Android 2.2. I am using 4GB SD card. I found on sdcard / android / data/ cache / com.sec.android.app.twlauncher / [lots of .db files] .
    What are these files?… Can I delete them ?.. becasue they are eating ~350MB memory on my card.

    • Jitesh

      I have exactly the same prolem as you have. I have googled but yet not got satisfactory answer, can anyone help.

      • http://hqraja.com Haroon Q. Raja

        Please see my above response.

        • Wouter Speybrouck

          As far as I know I don’t use TouchWiz and twlauncher folder is tanking 1 GB of my 2 GB card. T_T

          • Nilotpal Dutta

            Dude, i really had to deal with this prblm whn i 1st got this phn, u have to simply delete d cache folder inside it, n dont worry deleting it wont even matter your phone functionality, trust me, i delete the cache every month, kinda defect i guess with the stock Samsung TouchWiz, this problem has been rectified by Samsung on other newer devices but pitty it never cared to update this handset…

    • http://hqraja.com Haroon Q. Raja

      Those are files created by Samsung’s TouchWiz launcher. Removing them will not cause your system any harm, though you might (or might not) lose your launcher layout or settings. I don’t use TouchWiz and don’t know much about it.

      • Nilotpal Dutta

        nothing happens at all, nothing gets affected!! i keep doing it all the time! dont reply something you dont know yourself properly

        • asdasd

          Oh, shut up, you younger brother of a well known dev.

    • Wil Liam Yap

      this is your launcher=home screen, u cant delete it

    • https://plus.google.com/117789340197564487610/about Vivek Jindal

      Hi! I know this problem. These are cache files generated by touchwiz launcher. You can delete them anytime safely. Samsung softwares are very poorly developed. The cache files will be gonna build again with no size limits. You can clean them on weekly basis, no problem at all. Moving to 2.3.2 permanently resolves the issue.

  • Mohammed Shehata

    That’s great info really, thanks for sharing, but once you put your formatted SDCard into the slot, the system which running preinstalled apps will communicate with SDCard, scanning it, creating some folders to accommodate to some of those preinstalled apps, the basic folders are ….
    .android_secure
    .helix.thumbnails
    Android
    DCIM
    LOST.DIR
    rn-downloads
    And when you use your mobile and download more apps, you find more folders on your SD :). I guess you can add some infos about them also, Thanks again .

    • http://hqraja.com Haroon Q. Raja

      From the ones you mentioned, .android_secure contains the apps you have moved to SD card, Android may contain some OS-related data or some app data, DCIM is for camera images and LOST.DIR is a lost-and-found directory used by the OS. The rest that you mentioned are created by certain apps, and not all of these can be covered by us.

  • Axo409

    what partitions are included in a clockwork nandriod backup?

  • Axo409

    what partitions are included in a clockwork nandriod backup?

    • http://hqraja.com Haroon Q. Raja

      Usually boot, recovery, system, data and cache.

      • http://www.facebook.com/jairo.luis.ramirez Jairo Ramírez

        Hi Haroon, I have an issue wiyh my phone and I think you could help me to solve it. I just rebooted my previously rooted phone (Samsung Vibrant) into recovery (ClocWorkMod) in order to flash Cyanogenmod 7.2 ROM. There was no problems and it was “succesfully” installed; when I rebooted the phone I could see the CyanogenMod logo but after that it continued rebooting into recovery (CWM) once and again.
        Since I was in a hurry because had to travel I made a mistake (a really
        bad one), I formated the boot partition (Advanced options in CWM) and rebooted the phone without restoring any rom or boot partition (I had made a backup of my ROM before). The case is that now the phone doesn´t boot (not even in recovery mode), it shows the initial black screen displaying “VIBRANT and CYANOGENMOD and SAMSUNG” and stays like that pemanently.

        I was reading for a while and had lost any hope because everybody says
        the same I was thinking, that my phone was absolutely useless, It was
        not going to boot never again because of wiping the /boot. But then I
        read something in this thread tha made me wonder if there is any chance of making my phone
        boot again and how could it be. I would appreciate your help a lot, I made a backup of my rom with CWM but I don´t know if it would be useful now and how.

        Thanks in advance!

        Jairo Ramírez

        (jairoluisramirez@gmail.com)

        • Christopher Côté

          Check your Gapps version… You need to Install from ZIP both ROM and GAPPS

  • rprr

    Many thanks. My Android tablet does not have a /boot partition but it does have a separate /kernel and /ramdisk partitions. 

  • Vroshan96

    I have a problem with my galaxy s2 is not biting if I instal custom roms if I install stock it works and get error can’t mount sd card/cache/….
    Need your help

  • Vroshan96

    I mean booting issue

  • Sudhin Ad

    formatted /system on sony ericsson xperia mini pro. and it doesnt boot…plllzzzzzzz help…plizzz

    • http://twitter.com/stubborn_d0nkey Boris Babic

      It wont boot because there is no Android present, you have to flash another rom.

      Obviously, my post being 8 months after yours wont help but I’m writing this in case somebody in need might come along and read this.

      • http://www.facebook.com/jairo.luis.ramirez Jairo Ramírez

        You were absolutely right my friend… I just formated/wiped the /boot partition of my Samsung Vibrant and of course it doesn´t boot. So i would like to know if there is still something I can do for it. I would appreciate your help a lot.

  • Felix Vanderseen

    when you do a cache whipe and then a data whipe is then your phone as it came out of the box?
    or does the data whipe olso delete the stock rom that im using?

    • http://hqraja.com Haroon Q. Raja

      Data wipe only deletes user data and essentially performs a factory reset. The ROM doesn’t get effected by it.

      • Arcest

        As you say the ROM is just the /system folder, and then the operating
        system (Android) is supposed to NOT write anything there anytime, nor
        any app so remains “basically” as read-only?

        But, what happens if you edit something in the /system folder with, say, Root Explorer? It will remain changed even with a factory reset wouldn’t it?

        • http://twitter.com/stubborn_d0nkey Boris Babic

          Yes, a factory reset doesn’t affect the system partition. So if you added a system app it wouldn’t be deleted or if you deleted an app/something else it wouldn’t magically be restored.

          In some recoveries doing a factory reset doesn’t just wipe the data partition but also the cache and sdext partitions, as well as wiping android secure (or a combination of these extras. Obviously, if sd-ext is not present it wont be wiped)

  • Vimalmohanpillai

    ajrk007 and all others, you can delete the cahe files with xtn .db from 
    com.sec.android.app.twlauncher…

  • weihongcsu

    Great works!Thanks very much!

  • Al

    What about EFS partition?

    • http://hqraja.com Haroon Q. Raja

      That’s a Samsung-specific one I believe, and this post is about standard Android partitions primarily.

      • Arcest

        Could you edit the article to reflect it? I think is it important for two reasons, one that this folder is fundamental in some devices and second that it is not backed up on Nandroid / ClockWorkMod backups

  • zielmicha

    boot doesn’t hold bootloader. Only kernel and initrd.

    • http://hqraja.com Haroon Q. Raja

      Thanks for bringing this to my attention. At the time of writing this article last year, I wasn’t aware of this. I found out later but had forgotten about this post.

      • TareQ

        so where is the bootloader ?!!! I came here to this post and many others and read all that just to know where the bootloader is .

        • TareQ

          I have Note II btw

  • Angad Kumar

    Hey Hi,
    Nice introduction but there are lot of difference in different ROMs, like cyanogenMod usually doesen’t have /boot etc (And I think it uses ext 4 file system). 
    But I really want to know is that is there any way of partitioning my internal memory into two portions so that in one I can have cyanogenMod rom and in other another rom. (Note this dual booting my phone with using only internal memory and not sdcard, so that both roms work faster).  

    • http://hqraja.com Haroon Q. Raja

      This is currently not possible for most (almost all) phones. Though there are developers looking into it and some may have certain solutions (most probably in alpha stages) out there. Googling for your phone’s name/model followed by dual boot might help.

      • Vipul Nakashe

        Hi, is there a way of increasing the /data folder (or partition) size ? I have a big problem when i moved from the Nokia E90 to Samsung Tab GT-P1000 where it doesnt let me load more than 5000 contacts into the TAB as the memory gets full. I browsed through the folders and found out that the contacts storage file was located in the /dbdata folder (or partition) and the contacts app was stored in the /data folder (or partition)

        • Vipul Nakashe

          heres a link to my problem in a little more details. THanks :)

  • Jb9643

    Thank u so much for information 

  • Stephen

    I NEED HELP PLZ. After i rooted my phone my phone was working fine. however i went in to clockworkmod recovery, i didnt know what it was. so i just pressed reboot now but it would reboot back in to clockworkmod recovery so i thought i should just format or wipe everything . i have format my system and everything else. But it would still not work so i have downloaded a program that fix and help me get out of clockworkmod because i thought it would work if i get out of clockworkmod. i didnt know if i format my system it would not boot. can u help me how to boot my phone? like put a system back in or install? plz i need it quick!! couldnt use my phone for a month now

    • http://twitter.com/rovdrift

      Pay someone who knows what they’re doing to fix your mess, or start reading up on what CWM actually is and why you’re ending up in it. Your phone is probably missing a ROM/kernel completely.

  • Arcest

    There is the /mnt/sdcard/external_sd/ folder used for external (in some places called internal) memory card, for example in my case is a MicroSD. The external SD is placed then inside a folder of the internal SD.

  • Arcest

    misc and efs partitions are not backed up by ClockWorkMod Recovery at this time.

  • SK

    This is great info…..This makes me understand a lot of things I was trying to learn over the past 2 days. Below I’m mentioning a few points that I have understood…..Please these are just assumptions of my understanding…I might be wrong….Plz cement my understanding by just saying either true or false….You may correct the wrong assumptions…no force

    1. Users with unlocked bootloaders and the ability to boot into the bootloader (HTC) can do without a custom recovery…as they can do all that we do through CWM using the fastboot commands through cmd. (This point is clarified a bit from ur above post. Bootloader/fastboot mode can only replace a few features of CWM not all….CWM gives more advanced features. )
    2. Samsung users have unlocked bootloaders but cannot boot into it so cannot use fastboot commands. They need to flash CWM through ODIN by entering download mode.
    3. Download mode exclusive to samsung.
    4. fastboot commands be used with locked bootloaders.
    5. The boot.img is an image of the boot partition and same goes for recovery.img.
    6. boot.img contains the kernel and the ramdisk..so the bootloader location first loads this partition into main memory and the kernel then loads the OS and other stuff.
    7. HTC devices have access to bootloader (HBOOT) ie they can boot into the bootloader. From there they can use fastboot commands to direct the bootloader to boot into recovery mode….what this does is directs the bootloader to load the recovery partition into memory instead of the boot partition.
    8. Samsung users cannot directly address the bootloader as they cannot boot into the bootloader and hence cannot use fastboot commands. The key combinations (Volume up + ok + Power) that sammy users use to get into recovery are directions to the bootloader to load the recovery partition instead of the boot partition.
    9. On rooted phones, we can use apps to do the same thing from within the phone ie we are using apps with root access to instruct the bootloader to take us into recovery instead of using key combinations at boot.
    10. Even htc users can do so apart from the ability to directly instruct the bootloader by booting into it.

    Your help will be greatly appreciated

    Note : Samsung here refers to mostly R and S2 as I know that nexus users can boot into the bootloader.

    • joe spitz

      tftudfuyd6tyd7676td57d57sd47sd56

  • Whef

    I believe your description of /boot is still a bit off, perhaps because you didn’t adjust the rest of it after zielmicha’s correction. Since /boot doesn’t contain the bootloader, rebooting after deletion isn’t a problem. Furthermore, it can be useful for some developers; if you erase both the /boot and /recovery partitions, the phone automatically boots into the custom bootloader so you can manually load the partitions with the fastboot utility. Hope this is clear and helps!

  • rrgag

    I have samsung galacy ace phone, i was format /data partition then work a phone but IMIE number remove(status unknown),

  • pkjain2020

    Nice article, can you also explain how can we create a new partition… say /factory or say /vendor.. I google searched it and found no steps till now.

  • nikoko

    thanks for all you do for us.
    Merry christmas

  • PizzaMan92

    Thank you for this great guide :D

  • RGDnamics

    1 missing: “userdata”

  • dtak

    What does it mean when you get an error message “UID’s on the system are inconsistent, you need to wipe your data partition or your device will be unstable”?

  • JOHN

    i have wiped them all using CWM-based recovery, now my is not recognized by computer.. is there a way to get them back? when i plug my android phone into the computer, it’s only (D:) that appears.. i cant put zip files into my phone now… please help

  • joe spitz

    ugyjgbyjhigvbyhivih

  • Adeel Ahmed

    Awesome tutorial. I love it.

  • Kishan

    My HTC phone, when connected the PC, shows two VFAT partitions. One of them is external SD card, the one inserted in the slot provided. The other, I believe, is a VFAT partition in he internal memory of the device. That could be eMMC or NAND. On some phones I have seen an option like “user internal memory to store images”. I think this is referring to NAND’s or eMMC’s FAT32 partition.

    For example my HTC desire C has 4 GB internal memory, NAND may be. When I connect the phone to PC, I see a FAT32 partition of approx 100Mb. (this memory is different from the data partition used to store user data, which in my case is 0.94GB) Then another one of 8Gb, which is external SD card.

  • Sohail Ahmed

    I feel like an Android expert after reading this article. Thanks for making me feel so :).

  • ahmed

    good but i have formated the boot and system file and all the data i cannot even connect usb and cmw recover mood wont even recognise my sd card zip files ..what should i do??

  • QjKExt6c RL&7Z27ue

    Thank you for this useful info.

  • trainman261

    Wow, thanks for a very clear, detailed, straightforward explanation. Exactly what I was looking for.

  • Roy Garcia

    is there any way to resize the partition of /system? I only have 512MB. I already managed to partition my internal sdcard in to 2. 5.91gb for internal storage and 7.51gb for data storage.

  • nana

    Hi friends, I lost my contacts number in my Sony Xperia p cell phone. It is already in the cache of my cell phone but I do not know how I can bring it back. Would you please help me if you know?

  • Nicky Posmelo

    Hey all! :D I have a samsung galaxy next turbo (mini gt-s5570i) and i want to reinstall all the phone because /system and /sdext is broken or i don’t know :(
    I need help… i have android 2.3.6 gingerbeard

  • mark webber

    ah yes i like this info, and the way it is written. thanks :)

  • mungothecat

    How do I wipe the backup / recovery partition from my android device ?
    This is a serious question with a good reason..
    I have a problem with my phone – refusing to boot up on ocassion and have been offered a brand new replacement – but the device won’t misbehave to order and I need to help it out !!!