gzip archives coming up invalid!

[Steve Phillips]

On Thu, 6 Jan 2005, Chris W. Parker wrote:

> Hello,
>
> I've been running a script in /etc/cron.daily that tar's the /etc,
> /home, and /var directories and then gzip's them. After the gzip they
> are FTP'd to a backup server.
>
> I've just had the need to retrieve a file in one of the backups and it
> turns out they are all corrupt! This is not good. :(
>
> [root at hachiroku ~/temp]# gzip -t 01-01-05.home.tar.gz
>
> gzip: 01-01-05.home.tar.gz: invalid compressed data--format violated
> [root at hachiroku ~/temp]#
>
> This is the script I am using, maybe there is a problem with it?? Or
> maybe the corruption is happening during the FTP transfer?

If they are all corrupt then there is probably little you can do now.

As a suggestion, it may pay to modify the script, use ssh shared key 
authentication and scp for the upload and md5sum the files both before the 
transfer and after the transfer on the remote system (scp is not really 
necessary but shared keys allow you to do things like..

scp $local_file $remote_system:$remote_file

MD5=`md5sum $local_file`
REMMD5=`ssh $remote_system md5sum $remote_file`

if [ "$MD5" != "$REMMD5" ]; then
   echo "files dont match"
   exit
fi

quite easily to ensure that your files copied ok.)

Doing verification on the integrity of the archive before deleting the 
older versions is usually considered a good thing [tm]

-- 
Steve.