incorrect super block
Bob Johnson
bob89 at bobj.org
Thu Mar 11 21:06:34 PST 2004
On Thursday 11 March 2004 10:53 pm, lee slaughter <lee slaughter
<lee at slaughters.com>> wrote:
> >There is no filesystem support for mounting gzipped tar files as
> >filesystems, so you'll have to use it as a raw device.
> > tar -xzf /dev/acd1
> >should extract the data.
>
> no, i tried it with tar file. it got maybe 20% of way thru with
> unexpected eof.
>
> with tar.gz:
> tar: /dev/acd1: Cannot read: Input/output error
> tar: At beginning of tape, quitting now
> tar: Error is not recoverable: exiting now
>
> i just want to back up to a cd.
That should have worked. It seems likely you actually do have an error
on the CD. Although burncd has been more reliable for me than the
Windows CD burners I've used, it does rarely produce a coaster. Did you
write it at higher than the rated speed of the blank disk?
Example of a test of this method (running burncd at low speed to make
sure tar+gzip can keep up):
===
# tar -czf - temp/* | burncd -f /dev/acd0c -s 2 data - fixate
next writeable LBA 0
writing from stdin
written this track 3760 KB total 3760 KB
fixating CD, please wait..
#
# mkdir temptemp
# cd temptemp
# tar -xzf /dev/acd0c
gzip: stdin: decompression OK, trailing garbage ignored
tar: Child returned status 2
tar: Error exit delayed from previous errors
#
===
All of the unpacked files were identical to the originals according to
diff. The error message seems to indicate that tar pads blocks at the
ends of files with characters that confuse gzip.
I also did a test that produced 148 MB of tar.gz file, and it unpacked
fine (with the same error message).
- Bob
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