[GLLUG] CD-RW Packet Writing

Matt Graham danceswithcrows at usa.net
Fri Oct 15 12:27:20 EDT 2004


Marr wrote:
> 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. 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.

Flash memory is supposed to have at least 100,000 write cycles before it dies.
 CD-RWs have fewer than 1000 write cycles and maybe as few as 10, depending on
media quality.  Not to mention the low-speed vs. high-speed CD-RW formats
(can't write a high-speed CD-RW in a low-speed drive, can write low-speed
CD-RW everywhere but only at 4x.)

> Furthermore, packet writing to DVD-RW and DVD+RW media (although I 
> haven't yet done that) appears to be fully supported. 4.7 GB sounds 
> pretty enticing.

Maybe.

>> ISO9660 multisession works just fine and has less overhead/hassle 
>> associated with it. 
> If my math is correct, this is only true for around 10 or fewer sessions 
> per disc.

Yeah, that's correct--but that's what, about 60M/session?  USB keychain drives
start at 64M these days.

> The things I use packet writing for would use far more than 10 sessions 
> per disc.

What are you *doing*?

Right.  I guess my experience is semi-limited, since I've always carried my
laptop with me since ~2000.  (12 or 32G hard disk >> 4.4G DVD+-R.)  Most of
the time, I've had access to the larger hard disks on my home machine via
cable/DSL.  Things of a few M get transferred over the Net.  Things larger
than that get copied to my laptop disk.  I use CD-Rs and DVD+Rs for archival
and backup, not as removable media, since fast networks and scp make removable
media much less valuable IMO.

> > ?  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.

200K is small enough that it's easily transferable even over a 33.6 modem
connection.

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

This is an advantage, but not a compelling one for me.  When I burn something,
I want to keep it for a few years.  Transient files get stored on disk until
they get rm'ed (if they weren't worth keeping) or burned (if they were.)

> 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).

Segregation of files by subject?  Isn't that what directory trees are for? 
Samba/NFS/atalk + Cat5 = better sharability than multiple CDs in most cases. 
(Wait 10 years, and it'll be "all cases".  Your dog wants cable/DSL.)

> I need to look into 'k3b' more. I've not used it enough to comment, but 
> a lot of people seem to like it.

It is currently the best GUI frontend to cdrecord/mkisofs/cdparanoia/
dvdrecord/growisofs/lame.  XCDRoast needed the competition :-)

> 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.

Ubiquity?  You still can't count on a random machine having a CD-RW drive. 
CD-ROM, sure, but RW still isn't everywhere, particularly in places where the
machines all came from one vendor and the beancounters were out in force.  Joe
Homeuser will have an RW if he bought his x86/Mac in the last 2-3 years, but
Joe Corporateuser won't.  That may change in another few years.  USB 1.1 ports
and/or some type of connection to the wide Net are more common than CD-RWs
right now.

> 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.

The patch you talked about in your first message will make it less involved,
no?


-- 
Matt G / Dances With Crows
There is no Darkness in Eternity/But only Light too dim for us to see
"I backed up my brain to tape, but tar says the tape contains no data...."





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