Re: how to use growisofs to merge (-M) on the fly ?

[Bill Davidsen <davidsen@tmr.com>]

Joachim Braun wrote:

> Hi,
> I want to use growisofs to burn a premastered iso boot image, with a rescue system
> on it which contains scripts to dump or rebuild the machine to a earlier dumped State.
>
> growisofs -speed=1 -Z /dev/dvd=rescue.iso
>
> the next step is, to dump the disk's or partitions (at the moment to a nfs mounted disk):
>
> dd if=/dev/disk | gzip -9 > /nfs-mount/disk.dd.gz
>
> after this has finished the file is written to th dvd:
>
> growisofs -speed=1 -M -J -R /dev/dvd /nfs-mount/
>
> I'v made several tries to write on the fly (without the file on the nfs-mounted filesystem)
> via named pipes but did not hav any succes.
>
> the man page of growisofs contains a sample for initial writing throu a pipe, but this
> works only for preformatted (iso) images or parts of a mounted filesystem.
>
> i tried using named pipes but i got only the directory entry of the pipe to dvd:
>
> mkfifo /tmp/pipe.dd.gz
> dd -if /dev/disk | gzip -9 > /tmp/pipe.dd.gz &
> growisofs -M -J -R /dev/dvd /tmp/pipe.dd.gz
> rm /tmp/pipe.dd.gz
>  
The problem is that mkisofs can't build the image without knowing the 
size of the items for the directory entries, and it seems to get that 
information by looking at the sizes first. Someone could do what you 
want, I think, by writing a directory entry with a one block size, 
writing the file, and then writing a correct directory as another 
"fix-up session" after the data was written. It may be possible to put 
the record in the same session, I haven't researched this, as it's not 
my problem. And won't be unless the media being burned gets so large I 
can't afford to keep an image on a spare partition used just for that.

Another approach might be to use another filesystem than iso9660, and to 
use that. I can't suggest which without having tried a few things and 
read up on the issue, perhaps someone else will know.

--
bill davidsen <davidsen@tmr.com>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979