What kind of SD cards and formats are supported? Formatting and encrypting a card

Jolla Care -

This help article was renewed after publishing Sailfish 3.  Version 3.0.0 brought improvements to formatting cards and the support for encrypting them. Not all of the features work with earlier Sailfish OS versions. Please upgrade to the latest.


1. Introduction

1.1. Compatible cards

Sailfish OS supports microSD cards (SDHC cards) up to 32 GB of storage capacity in FAT32 and ext4 formats.

Sailfish OS can also handle SD cards with more storage capacity (64 GB, 128 GB, even more). These SDXC memory cards are typically sold in exFAT format which is not compatible with Sailfish OS. Therefore they must be formatted to ext4 before they can be used on Sailfish. Either the card is formatted on a computer before inserting it to a Sailfish device or else the user lets Sailfish to format it in menu page "Settings > Storage". Please note that formatting the card will wipe out all existing data from it.

Note that Windows and Mac computers are not able to show the contents of ext4 cards directly. However, if an ext4 card is inserted in a Sailfish device which is connected to a PC with USB, then the card and its contents is available for the file manager on the PC.

Inserting a card that is incompatible (e.g. in exFAT format) will lead to warning "The file system is incompatible. Formatting is needed" in in "Settings > Storage".

Some card brands or models may not be recognised by all Salifish-driven devices.

Note that this article is also valid for external storage device which can be connected with a special USB On-The-Go cable to your Sailfish device.


1.2. Terminology

The contents of an SD card can be protected by encrypting [1] it with Sailfish OS generation 3.

An unencrypted card is automatically mounted [2] (opened for use) on the system when the device is turned on the next time. After this, apps like Gallery can show the pictures and videos residing in the card. Camera app can be set to save pictures and video clips directly to the card.

An encrypted card must be unlocked by the user in "Settings > Storage" before it becomes available for the apps.


2. Formatting a card with Sailfish OS

Card operations are done in "Settings > Storage" menu. Tap and hold the memory card item - this makes the context menu appear with appropriate commands in it.

There is currently no option for the user to choose which format to apply. Sailfish OS will format cards with 32 GB or less storage space to FAT32, and bigger cards to ext4.

NOTE:  Please remember to unmount the card first (command: Unmount) before proceeding to Format, as an attempt to format a mounted card may lead to a broken card. This applies to OS version 3.0.0 especially, whereas 3.0.1 and later versions have checks for this, preventing those problem cases. Should this kind of failure happen, please format the card using a computer; then insert it to your Sailfish device. - There may be changes to this in the upcoming Sailfish OS releases.

EDIT: On 3.0.1 Format command contains a built-in Unmount command to  avoid unnecessary failures. Hence it is safe to run Format on a mounted memory device.

  •     You cannot use memory card encrypted with Sailfish OS on your PC.
  •     You cannot use memory cards encrypted with PC on Sailfish OS.


2.1. Formating a memory card without encrypting it

The following sequence of 6 pictures shows how the formatting takes place. In this case we do not want to encrypt the card.  Note that you will need to unmount the card first (use command "Unmount" in the context menu of "Settings > Storage") after which the card appears as in the first picture below. Then use the context menu again and select command "Format". The view of the 2nd picture below will appear.

 SD-card-noname-unmounted.jpg  SD-enter-card-name.jpg  SD-authorise.jpg

 SD-formatting-card.jpg  SD-card-formatted-unmounted.jpg  SD-card-ready.jpg


2.2. Formating and encrypting a memory card

The process of producing an encrypted and formatted card differs only in the 2nd picture below where one must define a passphrase that will be needed when unlocking the encrypted card for use.

Encrypted cards can be formatted again only when they are in locked state. Formatting removes the encryption as the option to encrypt is intentionally not available in this case. After this the card is formatted but unencrypted.  You can then format it again with encryption, if needed.

It is not possible to encrypt a card without formating it (i.e. without deleting the data).


 SD-card-noname-unmounted.jpg  SD-card-name-and-encr.jpg  SD-authorise.jpg

 SD-formatting-card.jpg  SD-card-unmounted-locked-encr.jpg  SD-card-encr-ready.jpg


2.3 Using an encrypted card

Every time you turn your Sailfish device on, you must unlock the encrypted memory card in "Settings > Storage" to make it available for the applications (the unlock command mounts the card automatically).  Without this the apps cannot "see" the card. For instance, Camera app cannot save pictures to the card, and Gallery app cannot present the pictures stored in the card.

See the pictures below.

SD-card-encr-locked-after-bootup.jpg  SD-card-encr-start-unlocking.jpg  SD-card-encr-unlock-give-code.jpg        SD-card-encr-authorise-unlocking.jpg    SD-card-encr-in-use.jpg 


Use the Lock command in the context menu of the card when you want to make its content hidden from Sailfish apps.

When a Sailfish device with an encrypted SD card in it is turned off, the card becomes locked up automatically.


3. Formatting an SD card to ext4 with Linux PC

It may not be possible to format an SD card using the utility in the pull down menu of Settings > Storage. This is known to have problems on Sailfish OS versions prior to 3.0.0.

Sailfish 3.0.0 will have improved SD card services.

Should you want to use a card with high capacity (64 GB or more) and make it to ext4 format, then we recommend doing the format with a Linux computer (or with PartitionGuru app, or similar, on Windows PC). While doing this please make sure that you know the device address of the card, so that you would not format a wrong card or disk.

The following commands should do it.  If your SD card is the only SD card on a Linux computer then it would probably appear as the device " /dev/mmcblk0p1 " which you can check with command


It is good to run the "lsblk" command with and without the card inserted in the slot of the PC to ensure that you know how the card appears on the PC (by seeing the difference).

This is how to format an SD card to ext4:

umount /dev/mmcblk0p1
sudo mkfs.ext4 -L "
nickname" /dev/mmcblk0p1


4. Path to the SD card

The path to the SD card (or the location of it) in Sailfish OS file system has been changed to OS version 2.2.0 as follows.

Symbolic link (from Sailfish OS 2.2.0 onwards): 


Actual path (from Sailfish OS 2.2.0 onwards): 


Both of the paths above can be used. Please update your File Browser app to the latest version from Jolla Store.


5. Moving data to/from the SD card

If you have a Windows or Linux PC, read this article.

If you have a Mac, read this article.



[1] Encryption is the process of encoding a message or information (here: the data in SD card) in such a way that only authorized parties can access it and those who are not authorized cannot. 
Source: https://en.wikipedia.org/wiki/Encryption

[2] Mounting is a process by which the operating system makes files and directories on a storage device (here: SD card) available for users and applications to access via the device's file system.
Source: https://en.wikipedia.org/wiki/Mount_(computing)



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