Re: HEADS-UP: UDF write support

[Christian Baer <christian.baer%uni-dortmund.de@localhost>]

Reinoud Zandijk wrote:

You can't believe the private little party that went on at my place when 
I read this! I could really kiss you for this but it's probably better 
to restrain myself just that little bit. :-)

> as you might have read on the source-changes list, i've committed write 
> support for NetBSDs UDF file system. It can now read and *write* files and 
> directories on CD-R, CD-RW, CD-MRW, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD+MRW, 
> (USB) flash media and harddisc partitions. Media like Iomega Rev should 
> also work fine since they attach to the cd(4) device.

I have to admit, that I don't follow the source changes that much (only 
when I actually have a lot of time to spare), so I am not all that 
informed about all the details.

I did notice that DVD-RAM is missing in the above list. Since DVD-RAM is 
an optical media but can be accessed like a hard drive, I'm guessing 
that it is supported too - hopefully not only as Mount Rainier or 
something evil like it.

> For recordable media and non optical media a newfs_udf(8) is enough. See 
> the manpage for the various options. Note that the UDF version specifying 
> is still a bit odd, it needs to be done in hex.

The manpage isn't online yet, so I have to ask: Does newfs_udf also 
offer a *physical* format like the Windows-tool does (formatting a 
DVD-RAM 3x takes about 42 minutes). I'm asking because after you've 
messed around on a DVD-RAM for a while the write speeds really go down 
(I've had write speeds that were somewhere around 0,5x). If you format 
the disc physically the speed goes back to normal.

> For all other media (i.e. NOT optical media), one has the choice to 
> completely use the disc by using the complete device extent or to use a 
> partition scheme. newfs_udf(8) will use the complete partition specified.

In that case it should be possible to put cgd(4) between the disc and 
the newfs or am I wrong about that?

> Current limitations are that disc accounting is not done correctly yet so 
> be carefull not to run out of space on disc and that writing to metadata 
> partitions is not implemented yet. Also fsck_udf(8) is not yet finished, 
> but will be added later.

What will happen if I run out of space? Will that corrupt the file 
system on the disc?

Regards
Chris