backup by inode to a disk file and direct restore

backup by inode to a disk file and direct restore

Post by Mike Ellwo » Fri, 10 Jul 1992 03:40:49



I've been experimenting using the backup command to do incremental
backups of a filesystem to a single temporary disk file.

The idea is to minimise the time the filesystem has to be unmounted thanks
to the quicker transfer time to disk, and no need for human interaction
to mount the tape. The temporary file will then be "dd"d to tape later,
(during the day). (There is a risk if you lose the disk before you
have time to copy, but at least it's only 1 days worth, and you may still
have one usable disk copy).

Well, I first tested,for simplicity, using backup by name, and it worked
perfectly, i.e. I did something like:
find . | backup -i -f- > my.temporary.file1

then

dd if=my.temporary.file1 of=/dev/rmt0

I could dd the tape back to another file, say my.temporary.file2
then restore from that with:
restore -f- < my.temporary.file2

HOWEVER, when I tried backing up by inode (incremental, not full)
, although the backup appeared
to work fine, the reverse process (as above +/-) failed, saying the
input from device - was not in backup format. The same error occurred
if I tried to restore directly from the file I'd just created, not even
going to tape and back via dd.

The good news was that I COULD restore directly from the tape (created
by the dd from my.temproary.file).
(piping a dd of the temp. file into restore didn't work either).

Does this sound like a bug (this is 3.1.5), or am I just trying to
do something impossible?

 
 
 

backup by inode to a disk file and direct restore

Post by Megan Stewa » Sun, 12 Jul 1992 01:02:38



Quote:Ellwood) writes:
> I could dd the tape back to another file, say my.temporary.file2
> then restore from that with:
> restore -f- < my.temporary.file2

> HOWEVER, when I tried backing up by inode (incremental, not full)
> , although the backup appeared
> to work fine, the reverse process (as above +/-) failed, saying the
> input from device - was not in backup format. The same error occurred
> if I tried to restore directly from the file I'd just created, not even
> going to tape and back via dd.

> The good news was that I COULD restore directly from the tape (created
> by the dd from my.temproary.file).
> (piping a dd of the temp. file into restore didn't work either).

> Does this sound like a bug (this is 3.1.5), or am I just trying to
> do something impossible?

You need to include the -B flag on the restore to indicate that the
dump file is read from standard input:

-B    Specifies that data being restored is from standard input.
      Normally, the restore command examines the actual backup medium
      to  determine  the  backup  format.   When piping the data to the
      restore command, this examination cannot occur.  The -B flag in-
      dicates that standard  input  is  in  the AIX Version 3 backup by
      i-node number.

Megan Stewart


 
 
 

1. dump/restore & inodes - are old backups obsolete ?

Hi,

I have just set up a RedHat 8 fileserver, and I plan on using
dump/restore for data backup on the partition housing the shared data.
I read at the bottom of the man page something about needing to do a
full dump (level 0) after restoring files, as the indodes will have
changed.

I'm just trying to get my head round this - does this mean that say a
6 month old tape could not be used to restore files that have already
been restored from a 1 month old tape ? Does this only apply to
situations where you are restoring files to a location where the same
files already exist ?

Thanks for any help going,

Craig Jackson.

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