[GLLUG] CD-RW Packet Writing

Marr marr at flex.com
Thu Oct 14 18:18:47 EDT 2004


On Thursday 14 October 2004 04:26pm, Matt Graham wrote:
> > At last week's meeting, someone
> > asked about packet writing on optical media.
>
> "Don't bother" would be my advice.  Packet-writing has a lot of overhead
> and 600M isn't as much data as it used to be.  If you have a few M to
> transfer, USB keychain drives typically make more sense than CD-Rs.  

USB keychain drives definitely have their place -- I use them too, for 
different reasons. But there's obviously no way they can match the CD-RW disc 
in media costs.

Furthermore, packet writing to DVD-RW and DVD+RW media (although I haven't yet 
done that) appears to be fully supported (per the instructions in the 
'packet-writing.txt' file) in the latest 'pktcdvd' patch/module. If 650 MB 
isn't enough, 4.7 GB sounds pretty enticing.  :^)

> If
> it's more than will fit on your keychain drive, ISO9660 multisession works
> just fine and has less overhead/hassle associated with it.

Depends on your point of view. If my math is correct, this is only true for 
around 10 or fewer sessions per disc. Any more than 10 sessions on a CD-RW 
and you're better off packet writing -- if disk waste (overhead) is your only 
concern. IIRC, the overhead for each session on a multi-session CD is 13 MB 
and (under Windows) a packet-writing-capable formatted CD-RW (worst case from 
many years ago, I don't think it's as bad now) is about 517 MB free 
post-format (on 650 MB media). The things I use packet writing for would use 
far more than 10 sessions per disc.

> > packet-writing CD-RWs is literally the last thing I still use Windows
> > for.
>
> ?  I just wonder why anyone bothers with packet-writing.

I can't speak for anybody else, but packet writing is a very nice way to write 
small files on a frequent but sporadic basis. Having a 13 MB/session 
multi-session overhead to write one or two 100 KB files just isn't tolerable, 
to me.

Furthermore, I can easily erase just one file on a packet-written CD -- that's 
just not possible on a multi-session CD.

A USB flash RAM drive qualifies in some cases, but not always. It just depends 
on lots of unspoken issues, like segregation of the files by subject and/or 
sharability of the media (both of which are better served by multiple CD-RW 
discs than by a single USB flash RAM drive).

>  k3b has a nice
> pointy-clicky interface to multisession ISO9660,

I need to look into 'k3b' more. I've not used it enough to comment, but a lot 
of people seem to like it. I appreciate the suggestion. I'm really more of a 
command-line guy, but I'm open minded to useful solutions.

> and before k3b existed,
> the mkisofs/cdrecord commands for multisession were all in the CD-Writing
> HOWTO and on groups.google.

Multi-session CDs have their place too -- I've used them (infrequently) in the 
past.

Bottom Line: I guess, for me, packet written CD-RW (and DVD+/-RW) media 
provide all the advantages of a floppy diskette (portability, ubiquity, 
inexpensive media, single-file-delete capability) but with truly huge 
relative capacity. That's still a very useful feature for some of us, despite 
the presence of USB flash RAM drives, multi-session CDs, etc.

Ultimately, I might (for now) agree with your "Don't bother" assessment about 
packet-writing under Linux, but only because it's currently too involved, not 
because it's not useful.

Regards,

Bill Marr



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