Microsoft exFAT by Tuxera

Android, Linux, QNX, FreeRTOS, SafeRTOS, Integrity, ThreadX
Available on a wide range of RTOS environments. Features and/or
specifications may vary depending on the operating system

ARM, ARM64, Intel x86/x86_64 or compatible, MIPS, MIPS64,
PowerPC, SH4, and more

• Conforms to all Microsoft exFAT versions including XP, Vista, Windows 7, Windows 8, Windows 10 (Microsoft Interop Vendor Alliance), and Windows 11
• Conforms to SD Association (SDA) specifications
• Support for all flash-based storage types such as SD cards, eSD, CF cards, SSD, UFS, USB-connected storages, SATA, eSATA, FireWire, and eMMC
• Support for APM, GPT, and MBR partition schemes

• Maximum volume size: 128 PiB
• Minimum cluster size: 512 bytes
• Maximum cluster size: 32 MiB
• Maximum file size: 128 PiB*
• Maximum number of entries per directory: 2,796,202
• Maximum filename length: up to 255 characters
• Supported sector sizes: 512, 1024, 2048, and 4096 bytes

The operating system and hardware platform may place additional limits
on maximum file size. E.g., Linux on 32-bit platforms limits the maximum
file size to 8 TiB with 4 KiB page size, and 128 TiB with 64 KiB page size

• 1 MiB of RAM
• Processor: 25 MHz

• Read-write: 70-90 KiB
• Read-only: 40-60 KiB
• CPU usage: 0-10%

Volume consistency ensured if storage is removed, or power or
battery is disconnected

Tuxera maintains POSIX File System Test Suite. The following
system calls are tested:
• chmod: changes permission
• chown: changes ownership
• mkdir: creates directories
• open: opens a file
• rename: changes file name
• rmdir: removes directories
• truncate: decreases/increases file size
• unlink: removes files

Microsoft exFAT by Tuxera uses free space bitmaps to reduce
fragmentation and to improve space allocation when files are
deleted

• Unicode Character Set (UTF-16). Exceptions: U+0000 (NUL)
through U+001F (US), / (slash), \ (backslash), : (colon),
*(asterisk), ? (question mark), “ (quote), < (less than), > (greater
than), and | (pipe)
• Unicode fulfills the need to support character differences in
national and regional languages (Japanese, Korean, Chinese,
Western, etc.).

OEM Parameters Sector for device-dependent parameters

Support for Universal Coordinated Time (UTC) timestamps

• Active superblock (FAT), file, directory, attribute and data caching. Advanced algorithms and data structures ensure maximum I/O throughput, low CPU usage for small and large files, and achieve high IOPS for file operations. Tunable settings. Low power use optimized for increased battery life.
• Free Area Management: Allocation Bitmap
• Cluster Chain Management:
• FAT Chain
• Directory Entry
• FAT + Continuous Information
• Name Search: Comparison of Name
• When saving files to SD, SDHC, SDXC, or SDUC cards, full
speed can be achieved
• Zero-copy support (direct I/O)
• Low data fragmentation

Rigorous quality assurance, wide deployment, and fault-tolerant
design guarantee outstanding file system robustness

Provides maintenance services so exFAT development can be
safely customized using:
• Product answers to inquiries
• Minor version product available

Proprietary, commercial

Note! Tuxera licenses the exFAT software implementation. We’re also a
part of the Microsoft exFAT licensing program. With our special
arrangement with Microsoft, you can purchase our proprietary exFAT file
system implementation, already covered by a full Microsoft exFAT
patent license.

• mkexfat: formats volumes
• exfatck: checks and repairs volumes
• exfatlabel: shows/sets volume label
• exfatsvn: displays/changes the volume serial number on an
exFAT file system
• exfatdebug: collects debug images

Recovery in the event of power failure or hot-unplug.