| Developer | ISO/ECMA/OSTA |
|---|---|
| Full name | Universal Disk Format |
| Introduced | 1995 |
| Limits | |
| Max file size | 16 EB |
| Max filename length | 255 bytes (path 1023 bytes[1]) |
| Max volume size | ? |
| Allowed characters in filenames | Any Unicode except NUL |
| Features | |
| Dates recorded | creation, archive, modification (mtime), attribute modification (ctime), access (atime) |
| File system permissions | POSIX |
| Transparent compression | No |
| Supported operating systems | FreeBSD, Linux, BSD, MS-Windows, Mac OS X, etc.. |
| Optical media types | |
|---|---|
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| Standards | |
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| See also | |
Universal Disk Format (UDF) is an implementation of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660. Due to its design, it is very well suited for incremental updates on both recordable or (re)writable optical media. UDF is developed and maintained by the Optical Storage Technology Association (OSTA).
Normally, authoring software will master a UDF file system in a batch process and write it to optical media in a single pass. But when packet writing to rewriteable media, such as CD-RW, UDF allows files to be created, deleted and changed on-disc just as a general-purpose filesystem would on removable media like floppy disks and flash drives. This is also possible on write-once media, such as CD-R, but in that case the space occupied by the deleted files cannot be reclaimed (and instead becomes inaccessible).
Multi-session mastering is also possible in UDF, though some implementations may be unable to read disks with multiple sessions.[2]
Contents |
The Optical Storage Technology Association standardized the UDF file system to form a common file system for all optical media. The goal was to make a common file system for read-only media and optical media that are re-writable. When first standardized, the UDF file system was intended to replace ISO-9660, allowing support for both read-only and writable media. After the first version of UDF was released, it was adopted by the DVD Consortium as the official file system for DVD Video and DVD Audio.[3]
Multiple revisions of UDF have been released:[3][4]
Universal Disk Format builds are as follows:
Packet writing was introduced in Revision 1.50. For write-once media, the entire disk is virtualized, making the write-once nature transparent for the user; the disk can be treated the same way one would treat a rewritable disc, but with steadily decreasing available space. For rewritable media, addresses are virtualized so that defect management (sector relocation) can be performed. However, UDF defect management does not apply to systems that already implement another form of defect management, such as Mount Rainier for optical discs, or a disk controller for a hard drive.
Incorrect or incomplete implementations of Revision 1.50 (or above) may result in compatibility problems due to improper virtualization in reading or writing the disk.
Many DVD players do not support any UDF revision other than version 1.02. Discs created with a newer revision may still work in these players if the ISO 9660 bridge format is used. As some popular DVD burning programs default to UDF version 1.5 when burning video DVDs, users have found it necessary to avoid using the software wizard and instead manually configure the burn to version 1.02. Even if an operating system claims to be able to read UDF 1.50, it still may only support the plain build and not necessarily either the VAT or Spared Universal Disk Format builds.
Mac OS X 10.4.5 claims to support Revision 1.50 (see man mount_udf), yet it can only mount disks of the plain build properly and provides no virtualization support at all. It cannot mount UDF disks with VAT, as seen with the Sony Mavica issue.[5] Releases before 10.4.11 mount disks with Sparing Table but does not read its files correctly. Version 10.4.11 fixes this problem.[6][7]
Similarly, Microsoft Windows XP Service Pack 2 (SP2) cannot read DVD-RW disks that use the Universal Disk Format (UDF) 2.00 defect management system.[8] This problem occurs if the UDF defect management system creates a sparing table that spans more than one sector on the DVD-RW disk. Windows XP SP2 can recognize that a DVD is using UDF. but, Windows Explorer displays the contents of a DVD as an empty folder. A hotfix is available for this[9] and is included in Service Pack 3. [10]
Terminology:
| UDF version | Non-plain | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Operating system | 1.02 | 1.50 | 2.0x | 2.50 | 2.60 | VAT | Sparing Tables | Write | Note |
| AIX 5.2, 5.3, 6.1 | Yes | Yes | No | No | Yes | (1.5 is default)[11] | |||
| AmigaOS 4.0 | Yes | Yes | |||||||
| BeOS/magnussoft ZETA/Haiku | Yes | Yes | Yes | Yes | Yes | Yes | |||
| DOS/FreeDOS, Windows 3.11 or older | No | No | No | No | No | No | No | No | No native support. |
| eComStation/OS/2 | Yes | Yes | Additional fee drivers on OS/2. | ||||||
| FreeBSD 5/6/7 | Yes | Yes | No | Yes | |||||
| Linux 2.2 | Yes | ||||||||
| Linux 2.4 | Yes | Yes[12] | |||||||
| Linux 2.6 | Yes | Yes | Yes | Yes[12] (2.6.26+) | Yes[12] (2.6.26+) | Yes[12] (2.6.26+) | Yes | partly (only up to Version 2.01) | Version before 2.6.10 supported fewer media types. Features requiring 2.6.26 weren't fully automatic until 2.6.30 of the kernel. |
| Mac OS 9 | Yes | Yes[12] | Yes | ||||||
| Mac OS X 10.4 | Yes | Yes | Yes | only with Toast 9+ HD Plugin | only with Toast 9+ HD Plugin | Can create UDF 1.50 (plain build) volumes using the drutil utility. |
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| Mac OS X 10.5 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | To create, use newfs_udf utility. |
| Mac OS X 10.6 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | To create, use newfs_udf utility. |
| NetBSD 4.0 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Reading multi-session VAT, spared and metapartition variants from all CD, DVD and BD variants as well as HDD and Flash media. |
|
| NetBSD 5.0 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Write support for all builds and media including multi-session VAT.[13] Create new with newfs_udf.Limited writing on 2.50/2.60 (due to needing pre-allocated, fixed sized metadata partition).[14] |
| Novell NetWare 5.1 | |||||||||
| Novell NetWare 6 | |||||||||
| OpenBSD 4.7 | Yes | Yes | Yes[15] | Yes[15] | No | Yes | |||
| Solaris 7 11/99+ | Yes | Yes | |||||||
| Solaris 8/9/10 | Yes | Yes | Yes | ||||||
| Windows 95 OSR2+/Windows 98/Me | Yes[12] | No | No | No | No | No | |||
| Windows 2000 | Yes | Yes[12] | No | No | No | No | |||
| Windows XP/Server 2003 | Yes | Yes | Yes[12] | Yes[16] | No | No | Write support available with third party utilities such as DLA and InCD. | ||
| Windows Vista | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Referred to by Microsoft as Live File System. |
| Windows 7 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | |
The specification allows for nine character encodings: one by agreement, one specified by ECMA-6 (also known as ASCII), three subsets of ASCII, a subset of ECMA-94 (Latin-1), and various other graphical characters.[17][18]
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