Re: [gentoo-user] [ot] Correct Setup for DVDRAM

[Simon <turner25@gmail.com>]

Storing data on a dvd is always quite useful and dvds cost much less than usb 
keys or other...  I've been thinking about one thing.

Is there any such thing as an incremental filesystem for write-once-read-only 
media (ie. DVD+-R)?...

A filesystem that would append the inode table at the end of the session at each 
session, and the table would refer to previous dvds, only the last table would 
be read, previous tables ignored (unless used for journaling)...  This would 
make that after some time of usage if you wish to copy certain files back to a 
hd, the filesystem would have to instruct you to insert a specific series of 
dvds in order to extract all those files (or blocks).  This of course will 
clearly result in waste and large number of dvds if used a lot in read-write 
operations (ie, nothing gets ever rewritten but instead can be no longer 
referenced by the table).

I've been thinking on hacking the ext2 kernel driver to support this kind of thing.

Of course the goal with such filesystem is for backup of individual files, but 
since I would be using something like a modified ext2fs, a very large file could 
be spread on multiple dvds, be fragmented and stored this way transparently.

Another way might be to use a read-writable media for storing the fs table. 
Possibly, using a modified ext2fs which would transparently work like a real 
ext2fs, a tool like rsync could be used to make true incremental backups using 
the hard-links trick.  But it could also be used like a rarely used hard-drive 
which does not suffer from magnetic deterioration (however unlikely this is).

Any such tool?
If not, this would be my first project dealing with kernel programming.

Simon

Florian Philipp wrote:
> meino.cramer@gmx.de schrieb:
>> Hi,
>>
>> since I own a LG HD-LT-DT GSA-4163B bruner, which
>> allows to burn DVDRAM discs I try to generate a
>> setup, which successfully writes data to a DVDRAM.
>>
>> Everything else works fine. But writing a complete DVDRAM
>> takes "hours". As recommended I use UDF as the filesystem
>> of choice -- no unnessary rewrite of the same sectors of
>> the DVDRAM.
>>
>> I tried to use packet-writing but ot does not help.
>>
>> Is there any "definite" recipe how setup everything to
>> get any reasonable transfer rate to and from the DVDRAM
>> or is it simply not possible with Linux?
>>
>> Any help is very appreciated -- thank you very much in advance!
>> mcc
>>
> 
> I've given up packet writing a long time ago. It never worked for me.
> 
> IMHO both udftools and the kernel driver are not really usable (just try
> udffsck ...) and with the advent of flash memory I don't think anyone
> will invest a lot of work in either one.
>