Re: Universal Disc Format (UDF) -- WAS: HD Backup

[Stan <swzaske@yahoo.com>]

Thanks for the extensive reply Bryan. @:D>


On Monday 02 January 2006 15:01, Bryan J. Smith wrote:
> On Mon, 2006-01-02 at 02:47 -0600, Stan Zaske wrote:
> > This UDF cross platform file system for removeable hardrives has me
> > curious. How would one go about formating a drive with it. I'm a Linux
> > "noob" and am unable to share with my other PC's formatted with NTFS. I'm
> > running Kubuntu 5.10 AMD64 "Breezy Badger" by the way. @:D>
>
> UDF is probably the most flexible filesystem you'll ever see.  Like a
> block filesystem (Ext2/3, NTFS, etc...), it has structures, extents and
> can be written to read/write.  Like a pre-mastered/archive** filesystem
> (ISO9660, ustar/stream, etc...), it can be generated into a single file
> that is only as large as its data.
>
> - Pre-mastered/Archive UDF (most commonly known)
>
> [ **NOTE:  The "dump" programs for various filesystems actually give it
> similar capability, although with some limitations and not quite as
> absolutely encapsulating -- e.g., xfsdump, e2fsdump, etc... ]
>
> There are various user-space programs to use UDF as a pre-
> mastered/archive filesystem.  E.g., mkisofs can generate UDF images,
> instead of ISO9660.  This, of course, generates a pre-mastered/archived
> "read-only" version that is not directly usable -- just like
> ustar/stream** or dump is not.  So this is _not_, of course, what you
> use for a removable/external drive.
>
> [ **NOTE:  ustar/stream can be appended to, of course.  Then again, you
> can have multitrack/multisession ISO/UDF media, etc... ]
>
> - Block Filesystem UDF (reweritables, flash, removables, fixed)
>
> As flash devices have started to pass the 8GiB (8.4GB) size, many are
> now offering UDF as a filesystem option instead of FAT32 because of
> various XP limitations beyond 32GiB (33.8GB) and 128GiB (137GB).  Newer
> Rigid Removable Disc (RRD) drives, such as the IOMega Rev, also use UDF.
> HD-DVD continues to standardize on UDF, and many BluRay supporters are
> demanding UDF be the default format (even though BluRay has its own
> filesystem -- long, long story).
>
> Like most "regular" filesystems, UDF has a kernel driver and a set of
> userspace tools.  But that's where some of the similarities differ.  UDF
> is clearly not a "high performance" filesystem**, being that it does all
> sorts of checks and, being designed for removables -- especially optical
> (where the write error rate is 10^9 versus the typical 10^13 for
> magnetic) -- expedites commits.  This is also why it is being preferred
> over FAT32 for newer flash/removables.  With DVD-RAM, it has an
> integrated verify-after write (which cuts performance down 45%, but
> reduces error rates 4-5 orders of magnitude).
>
> [ **NOTE:  It's still a _lot_ faster than the user-space rewritable NTFS
> drivers for Linux, in addition to being a lot safer. ]
>
> Linux had UDF support very early on because Linux was used, like most
> UNIX, was a key optical archiving platform.  From proprietary optical to
> Panasonic PD-CD to the DVD-RAM standard and on-ward, UDF was around in
> kernel 2.0 and various user-space tools sprung up around it.  Remember,
> this was back when hard drive sizes were barely reaching 1GB, and
> optical archiving jukeboxes were 10s of GBs, and a universal filesystem
> was needed.
>
> - Kernel driver:  udf
>
> First off, see if your kernel has UDF built:
>   modinfo udf
>
> Most kernel 2.6 versions should, and most latter 2.4 kernels should as
> well.  Again, UDF support has been around since the 2.0 days, although
> it wasn't really until the 2.3 experimental branch that it was largely
> feature complete (version 0.9.x, circa 2000).
>
> With the UDF driver, you can both read _and_ write to various UDF media
> in addition to fixed disks -- various removable discs, CD-RW, DVD-RAM,
> DVD-RW and DVD+RW.  Some removables need to be formatted UDF (DVD-RW,
> DVD+RW), while others are hard-formatted UDF (DVD-RAM, many non-standard
> removables).  E.g., you'll know a DVD-RAM disc when you see it, it's got
> "dash holes" in it which is its hard-formatted UDF CLV (constant linear
> velocity -- CAV, CLV and CLV-Z are not a big deal for "single groove
> recorded" media, but make all the difference in "a pie-slice/like-a-
> fixed disc" rewritables ;-).
>
> The issue is when you need to format UDF on a media that doesn't come
> preformatted.  This would, of course, included fixed disks or those with
> disk labels and slices (partition table and partitions).
>
> - User-space tools:  udftools
>
> The UDF tools were a compilation of various UDF tools that were separate
> in the '90s (and were a pain to track down individually).  The 0.9.x
> release (which matched the kernel driver) has been stable since the
> 2000.  There have been a few augmentations and improvements, resulting
> in the 1.0.0 beta releases since early 2002.  The latest was the 1.0.0b3
> release in early 2004 -- which seems to be largely a release that
> addresses kernel 2.5/2.6 and DVD+RW.
>
> The UDF SourceForge page for the UDF tools is here:
>  
> http://sourceforge.net/project/showfiles.php?group_id=295&package_id=38129
>
> The user-space tools included are as follows ...
>
>   cdrwtool -- allows you to blank CD-RW (and some other, depending on
> kernel support) media.  You won't need this tool for hd slices
> (partitions), and you should only use it when directed for your exact
> DVD drive type** and media.
>
>   mkudffs -- make UDF filesystem.  About the only options to be aware of
> are "--media-type" (you'll want to use "hd") and the character set
> options ("--u8" "--u16" and "utf8" -- you'll want "--u16" for Windows
> compatibility IIRC, but it should be the default).  Windows XP should
> have UDF 2.01 support, although if you need to, fall back to 1.5 (-r
> 0x0150).
>
>   E.g., typical external hd format command ...
>      mkudffs --media-type=hd /dev/sdX#
>
>   pktsetup -- shouldn't be needed for kernel 2.6 (although it depends on
> kernel drive support), as the 2.6 kernel can packet write to many CD-RW,
> DVD-RW and DVD+RW drives directly (direct DVD-RAM support has been in
> since late kernel 2.2).
>
> [ **NOTE:  Drive type is more of an issue with DVD support than the
> drive media.  E.g., even if you use -R on a "dual format capable drive",
> Sony/Philips +RW drives have a different command set than DVD Consoritum
> -RAM/-RW drives. ]

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