Configuration Examples

IN THIS DOCUMENT

Below are examples of external storage configurations for various device types. Only the relevant portions of the configuration files are included.

Due to configuration changes in Android 6.0 (like the removal of thestorage_list.xml resource overlay), the configuration examples are split into two categories.

Android 5.x and earlier

Physical primary only

This is a typical configuration for a device with single external storage device which is a physical SD card, like Nexus One.

The raw physical device must first be mounted under /mnt/media_rw where only the system and FUSE daemon can access it. vold will then manage the fuse_sdcard0 service when media is inserted/removed.

fstab.hardware

[physical device node]  auto  vfat  defaults  voldmanaged=sdcard0:auto,noemulatedsd
init.hardware.rc
on init    mkdir /mnt/media_rw/sdcard0 0700 media_rw media_rw    mkdir /storage/sdcard0 0700 root root    export EXTERNAL_STORAGE /storage/sdcard0service fuse_sdcard0 /system/bin/sdcard -u 1023 -g 1023 -d /mnt/media_rw/sdcard0 /storage/sdcard0    class late_start    disabled
storage_list.xml
<storage    android:mountPoint="/storage/sdcard0"    android:storageDescription="@string/storage_sd_card"    android:removable="true"    android:primary="true"    android:maxFileSize="4096" />
Emulated primary only
This is a typical configuration for a device with single external storage device which is backed by internal storage on the device, like Nexus 4.
init.hardware.rc
on init    mkdir /mnt/shell/emulated 0700 shell shell    mkdir /storage/emulated 0555 root root    export EXTERNAL_STORAGE /storage/emulated/legacy    export EMULATED_STORAGE_SOURCE /mnt/shell/emulated    export EMULATED_STORAGE_TARGET /storage/emulatedon fs    setprop ro.crypto.fuse_sdcard trueservice sdcard /system/bin/sdcard -u 1023 -g 1023 -l /data/media /mnt/shell/emulated    class late_start
storage_list.xml
<storage    android:storageDescription="@string/storage_internal"    android:emulated="true"    android:mtpReserve="100" />
Emulated primary, physical secondary
This is a typical configuration for a device with multiple external storage devices, where the primary device is backed by internal storage on the device, and where the secondary device is a physical SD card, like Xoom.
The raw physical device must first be mounted under /mnt/media_rw where only the system and FUSE daemon can access it. vold will then manage the fuse_sdcard1 service when media is inserted/removed.
fstab.hardware
[physical device node]  auto  vfat  defaults  voldmanaged=sdcard1:auto
init.hardware.rc
on init    mkdir /mnt/shell/emulated 0700 shell shell    mkdir /storage/emulated 0555 root root    mkdir /mnt/media_rw/sdcard1 0700 media_rw media_rw    mkdir /storage/sdcard1 0700 root root    export EXTERNAL_STORAGE /storage/emulated/legacy    export EMULATED_STORAGE_SOURCE /mnt/shell/emulated    export EMULATED_STORAGE_TARGET /storage/emulated    export SECONDARY_STORAGE /storage/sdcard1on fs    setprop ro.crypto.fuse_sdcard trueservice sdcard /system/bin/sdcard -u 1023 -g 1023 -l /data/media /mnt/shell/emulated    class late_startservice fuse_sdcard1 /system/bin/sdcard -u 1023 -g 1023 -w 1023 -d /mnt/media_rw/sdcard1 /storage/sdcard1    class late_start    disabled
storage_list.xml
<storage    android:storageDescription="@string/storage_internal"    android:emulated="true"    android:mtpReserve="100" /><storage    android:mountPoint="/storage/sdcard1"    android:storageDescription="@string/storage_sd_card"    android:removable="true"    android:maxFileSize="4096" />
Android 6.0
Physical primary only
This is a typical configuration for a device with single external storage device which is a physical SD card, like the original Android One. There is no secondary shared storage and the device cannot support multi-user.
fstab.device
/devices/platform/mtk-msdc.1/mmc_host*         auto        auto       defaultsvoldmanaged=sdcard0:auto,encryptable=userdata,noemulatedsd
init.device.rc
on init    # By default, primary storage is physical    setprop ro.vold.primary_physical 1    
Emulated primary only
This is a typical configuration for a device with single external storage device which is backed by internal storage on the device, like Nexus 6.
Primary shared storage (/sdcard) is emulated on top of internal storage.No secondary SD card storage.USB OTG storage devices supported.Supports multi-user.
fstab.device
/devices/*/xhci-hcd.0.auto/usb*             auto            auto    defaults                                                    voldmanaged=usb:auto
Emulated primary, physical secondary
This is a typical configuration for a device with multiple external storage devices, where the primary device is backed by internal storage on the device, and where the secondary device is a physical SD card, like Xoom.
Primary shared storage (/sdcard) is emulated on top of internal storage.Secondary storage is a physical SD card slot that can be adopted.Supports multi-user.
fstab.device
/devices/platform/mtk-msdc.1/mmc_host*           auto      auto     defaultsvoldmanaged=sdcard1:auto,encryptable=userdata