gzip GB file limit

Mike Schroll LogicX at mail.isc.rit.edu
Wed Feb 25 06:39:34 PST 2004

I recently backed up my data before blowing away a partition with
tar -cvf - /docs |gzip -> /docs.tgz
-- it went through fine, no errors.

I've now discovered that the gzip which ships with FreeBSD 5.x base,
1.2.4 has a 2GB or 4GB file size limit on the file it creates...
the file created by that command was 4.9GB,
now when I extract it I get
gzip: docs.tgz: invalid compressed data--format violated

I tried following: http://www.gzip.org/recover.txt
gzip -d docs.tgz
bytes_in -1331625984

gzip: docs.tgz: invalid compressed data--format violated

I haven't continued, as that seems like an invalid number, and I'm not
even sure if those instructions have any relevance to me ---

I was able to do gzip -cd docs.tgz |tar -xvf -
and I can get 5.5GB of uncompressed data (the first 4GB of compressed
now I need to figure out a way to get the last of this file.
I've already installed gzip 1.3.5 from the ports collection, and have
been working with that.

My problem seems unlike many of the others I've seen -- my file
probably isn't corrupt, its just too big; and I hope my original data
is in there somewhere.

If anyone recommends hex editing, could you also recommend a good hex
editor, especially one which is able to deal with a multi-gigabyte
file w/o loading it all into ram.

Ironically to protect against a problem like this, I had made a backup
to DVD+R also, of the raw files, but somehow that DVD is also
unreadable -- I used burnatonce in windows (as I have many times
before) though I turned on some odd options, such as Relax ISO9660, No
Folder Limit, ISO Level 2 and now I get 'incorrect function' trying to
access the CD in windows, and a linux box refuses to mount the disc.

Thanks in Advance,

Mike Schroll

Applied Networking System Administration Undergrad
Rochester Institute of Technology

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