Hi,
On Mon, 25 Feb 2008 20:34:31 +0100, wrote:
You might want to play with the -P option to dump. Your above could be
written as:
dump -aL0 -P 'compress -c' /MYFILESYSTEM | cdrecord dev=... -
Unfornunately this does not work as you expect. Dump just takes
its data an pass it to the script specified to -P.
It does not grab the output of the script to count the data after-
wards. This means the -a option does not work at all (because a
pipe has no EOM-Signal) and the -B option will limit the input
data only:
$ dump -0 -B 100 -P 'dd' /dev/md4 > /dev/null
DUMP: Date of this level 0 dump: Mon Feb 25 21:11:40 2008
DUMP: Date of last level 0 dump: the epoch
DUMP: Dumping /dev/md4 to child pipeline process
DUMP: mapping (Pass I) [regular files]
DUMP: mapping (Pass II) [directories]
DUMP: estimated 30022 tape blocks on 291.38 tape(s).
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
200+0 records in
200+0 records out
102400 bytes transferred in 0.031908 secs (3209223 bytes/sec)
DUMP: Closing child pipeline process
DUMP: Change Volumes: Mount volume #2
DUMP: Is the new volume mounted and ready to go?: ("yes" or "no")
In contrast with:
$ dump -0 -B 100 -P 'compress -c' /dev/md4 | dd > /dev/null
DUMP: Date of this level 0 dump: Mon Feb 25 21:12:23 2008
DUMP: Date of last level 0 dump: the epoch
DUMP: Dumping /dev/md4 to child pipeline process
DUMP: mapping (Pass I) [regular files]
DUMP: mapping (Pass II) [directories]
DUMP: estimated 30022 tape blocks on 291.38 tape(s).
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
DUMP: Closing child pipeline process
DUMP: Change Volumes: Mount volume #2
DUMP: Is the new volume mounted and ready to go?: ("yes" or "no") ^C
59+1 records in
59+0 records out
30208 bytes transferred in 6.315456 secs (4783 bytes/sec)
Assuming that compress -c & cdrecord play nice (which your magic
device solution also requires)
My solution can just close the pipe at the one "end" of the magic
device which would be realy simple to implement in a script.
Of cause cdrecord will indeet close the pipe when the media is full. But
I think the media will not be usable since there is i.e. just no
more space for finalisation of the dvd.
But this is not a big probleme since I can use my "count compressed
data and close stdin after is reaches limit x"-script.
Well, if -B worked on compressed output, then you could split it up
on volumes, which wouldn't be quite so bad. So add making -P and -B
play nice together (again, they don't seem to as of 6.2) as a
possible solution.
Yes - this would be the best solution at all. But as I wrote - the
-B option only counts the data thats thrown out to stdout from dump
and doesn't fetch stout again.
Changing this behaviour of dump would break the backward compati-
bility. (However - I could introduce a new Option i.e. -C for compress :-)
But I worrie about updates with such a modified dump because I
would have to patch the original dump every time after I'd
updated my system.
How hard is it to get those a change into the CORE-Tree when coded
and tested well?
Thank you,
Martin L.
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