> I had over 20G of data that I wanted to backup before I re-build my
> linux machine. Due to disk space constraints, I tarred it all up and
> then compressed it using bzip2. It shrank down to around 11G file.
> Before storing the data file, I verified bzip2 integrity using bzip2
> utility. There are other alternatives to doing a more reliable backup,
> but this process seemed pretty fast and simple.
> Everything was fine until I copied the data file back and tried
> decompressing it. bzip2 utility complained about CRC errors. Hence I
> used bzip2recover to recover undamanged bzip2 blocks. Uusually those
> blocks (depending on how they are intially set when creating bz2
> compressed file) are 900K chunks. bzip2recover utility apparently
> receovered all 13500~ blocks, and stored them in 900K sized bz2-format
> So in order to get the orignal 20G tar file, I started unziping each
> compressed block and then combining the resulting data files together.
> That process is quite lenghty and taking a long time.
Hmmmm... I think see your problem... it basically boils down to not
having enough of the right kind of storage media and/or a solid tested
plan for using it.
I apologize in advance if some of what follows sounds harsh or uncaring
but when it comes to solid backup plans, as you will learn, there is zero
room for error... and by extension... very little room for kindness and
With that said... I think I do understand the position you are in. I hope
for your sake that your livelihood does not depend on the recovery of all
Are/were all these files located in a single subdirectory off of / ? Perhaps /home or
/var? If a single subdirectory was it also a separate partition? If you
had kept the data in its own subdir on its own partition you could have avoided
the neccessity of moving it off of the current media in the first place.
What version of bzip2 are you using? According to the manpage versions
1.0.1 and earlier have a limit of 512MBytes for file size. This
restriction is removed with version 1.0.2. Not sure what the max is after
Also according to the manpage the way to restore the original file after
completing a successful bzip2recover is to do this:
bzip2 -dc rec*file.bz2 > recovered_data
Does that work? If so then, I guess you can untar the recovered_data
In the future... you should consider a more robust backup plan. If your
data is valuable to you and/or your employer then you should consider
getting,at the very least, one or more backup disks so that the data can be
mirrored. Even better... get a good tape backup system. I have had very
good luck with DLT tapes and drives. I have had very bad luck with
DAT/DDS tapes and drives. A DLT tape system can handle up to 40/80G of
data and 200+G in the SuperDLT drives.
Having a good (and tested) backup plan means never having to say you are