Re: [Bug-tar] incremental backups--full backup after upgrading to newer tar

[Andrew Henry]

Sergey Poznyakoff wrote:
> On the first backup, tar needs to convert existing snar files to new
> format, supplying default values for missing fields. Unfortunately, this
> causes full backups to be generated. This is done only once, and
> subsequent backups will work as expected. 
>
> Regards,
> Sergey
>   
Does this mean that a previous level 0 backup can still be used during a
restore if I have a level 2 backup that has been performed with the
newer version of Tar, i.e.:

level 0 backup done with tar 1.18-2   17GB
level 1 backup done with tar 1.18-2   2GB
level 2 backup done with tar 1.19-2   19GB


Can these 3 files be used to restore a system assuming that the newly
installed system is using tar 1.19-2?

I did something that was probably a dumb idea.  I hand edited the snar-2
file (level-2 backups) and changed the version of tar on the first line
back to 1.18-2 which had been updated to 1.19-2 during the conversion
you mentioned.  Have I potentially broken something?  I performed a
second level 2 backup using the hand edited file that resulted in a full
backup.  I then performed another level 2 backup by copying snar-1 to
snar-2 but it is still saying 1.18-2 in snar-2.  Is the conversion a
one-time action even if the snar file version header gets changed back
to 1.18-2?  Is the rest of the snar file still upgraded despite the fact
that I have copied snar-1 over the top of the converted snar-2 file?


Regards,
andrew.