SD card content
This topic provides information about how Windows Phone treats content on SD cards.
Supported content
Windows Phone supports the following content on SD cards:
Apps (new in Windows Phone 8.1)
Music
Photos
Videos
Map data
Side loading application XAPs
Some app data, in particular, user content in non-system managed locations (for example, e-books)
SD cards do not support the following content:
Microsoft Office files
Email
Text messages
Contacts
Anything else not mentioned in the supported content list
SD card content requirements
Content that will be stored on the SD card must meet the following requirements.
Core experience – Do not put any content that is necessary for core phone experience and scenarios on the SD card because users can remove the card at any time.
Removable support – Applications that store references or links to content on the SD card in internal storage need to have a way to gracefully handle the SD card is removed. This can add complexity to the applications.
Performance – With SD cards, there is no chassis requirement to enforce minimum performance. Therefore, applications that access the content on the SD card should be able to tolerate a variety of performance characteristics of the storage. In general, SD cards perform well with sequential access and poorly with random access. Therefore, it is better to constrain the SD card to storing files that are accessed sequentially, such as media files, and to avoid putting files that are accessed randomly, such as databases, on the SD card.
Reliability – SD cards often have lower reliability than internal eMMC parts. Therefore, don’t put critical or frequently written content on the SD card.
Encryption – To enable interoperability scenarios, the SD card is not encrypted by default. In addition, the hardware lock capability of SD is not used. Therefore, content that needs to be encrypted should not go on the SD card, or it must be encrypted by the application. There are currently no plans to support encryption on the SD card.
Security – Because the SD card is formatted in FAT/exFAT file system format and can be modified offline, you cannot put ACLs on the card. You must assume that all applications can access all of the content on the SD card.
NTFS features – NTFS includes some features - such as symbolic links, ACLs, and alternate data streams - that FAT or exFAT file systems do not provide. Any applications that rely on NTFS-specific features for their files cannot store the files on the SD card.
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