backups & cloning

[Jerry McAllister]

On Tue, Sep 29, 2009 at 10:48:30PM -0400, PJ wrote:

> Polytropon wrote:
> > On Tue, 29 Sep 2009 21:26:19 -0400, PJ <af.gourmet at videotron.ca> wrote:
> >   
> >> But what does that mean? But ad2s1a has just been newfs'd - so how can
> >> it be dumped if its been formatted?
> >>     
> > When you're working on this low level, triple-check all your
> > commands. Failure to do so can cause data loss. In the example
> > you presented, ad1 was the source disk, ad2 the target disk.
> > You DON'T want to newfs your source disk.
> >   
> >> And what exactly does stdout mean?
> >>     
> >
> > This refers to the standard output. In most cases, this is the
> > terminal, the screen, such as
> >
> > 	# cat /etc/fstab
> >
> > will write the /etc/fstab to stdout. If you redirect it, for
> > example by using > or |, you can make stdout a file, or the
> > input - stdin - for another program.
> >
> > This is how the dump | restore process works: It leaves out
> > the "use the tape" or "use the file", but instead directs the
> > output of dump - the dump itself - to the restore program as
> > input to be restored.
> >   
> >> What is dump doing? outputting what to where exactly?
> >>     
> > The dump program is outputting a dump of the specified partition
> > to the standard output, which in this case is directly trans-
> > mitted to the restore program, which "picks it up" and processes
> > it = restores it.
> >
> >> I don't see it or
> >> should I say, understand this at all.
> >
> > Have a look at the command line again, simplified:
> >
> > 	# dump -0 -f - /dev/ad0s1a | restore -r -f -
> >
> > Run the dump program, do a full backup of the 1st partition of
> > the 1st slice of the 1st disk, write this dump to the standard
> > output, pipe this output to the restore program, do a full
> > restore, read the dump to be restored from standard input.
> >   
> >> and then the restore is from what
> >> to where?
> >
> > The restore program gets the dump to be restored from the standard
> > input - remember, that's the output of the dump program - and
> > writes it to the current working directory. That's the reason
> > why you should always check with
> >
> > 	# pwd
> >
> > in which directory you're currently located, because that will
> > be the place where the restored data will appear.
> >   
> >> "write error 10 blocks into volume 1
> >> do you want to restart:"
> >>     
> >
> > Could you present the command you're actually using, especially
> > with where you issued it from?
> >   
> Duh.... I think I see where this is leading... I'm pretty sure it was
> issued from / which makes it redundant, right? I should have issued it
> from somewhere else, like from home, usr or whatever but not from / as
> that is what I was trying to dump.... :-[

No, that is not a problem.   You can be in any directory and do the dump
command, except if you want that restore to work you have to be in
the receiving filesystem/directory.

I just noticed that I missed that you were newfs-ing the wrong partition.
That was the one you wanted to read from and your newfs would wipe out
everything on it.    If you do the newfs - a good idea - it has to be
on the new filesystem you will be writing to.

////jerry



> >   
> >> The first time I tried with -L the error was 20 blocks...
> >> Both the slices for dump from and to are same size (2gb) and certainly
> >> not full by a long shot ( if I reccall correctly, only about 14% is used)
> >>     
> >
> > I'm not sure where you put the dump file. "Write error" seems
> > to indicate one of the following problems:
> > 	a) The snapshot cannot be created.
> > 	b) The dump file cannot be created.
> >
> >
> >
> >   
> >> And what's this about a snapshot? AFAIK, I'm not making a snapshot;
> >> anyway, there is no long pause except for the dumb look on my face upon
> >> seeing these messages.
> >>     
> >
> > Check "man dump" and search for the -L option. The dump program,
> > in order to obtain a dump from a file system that's currently in
> > use, will need to make a snapshot because it cannot handle data
> > that is changing. So it will dump the data with the state of the
> > snapshot, allowing the file system to be altered afterwards.
> >
> >
> >
> >   
> >> As it is, I am currently erasing the brand new 500gb disk on which I
> >> want to restore.
> >>     
> >
> > Excellent.
> >
> >
> >
> >   
> >> Things started out really bad... don't u;nderstand what is going on.
> >>     
> >
> > Polite question: Have you read the manpages and the section in the
> > Handbook?
> >   
> Yes... but my brain can't handle it all so quickly... and being as
> impatient as I am, I tend to miss things on the run... it usually comes
> to me sooner or later... unfortunately, it's more often later than
> sooner... I've been reading the stuff in the man pages, and getting more
> confused by googling... Actually, I've been trying to get things
> straightened ot for at least 3 days already.
> >
> >
> >   
> >> I
> >> installed a minimal 7.2, booted up and turned to another computer to do
> >> some serious work. About 2 hours and 49 minutes later I notice messages
> >> on the 7.2 about a page fault or something like that and then the system
> >> reboots.
> >>     
> >
> > This often indicates a hardware problem...
> >   
> Well, that's why I'm really checking my new disk... but it could be the
> motherboard... I've always suspected it had something of a glitch in it
> ever since I got it... I don't think just a slower cpu should give it so
> many problems... a twin computer has the same hardware except for the
> cpu and it gives far less problems - only MS related.
> >
> >
> >   
> >> Obviously with errors... but then I reboot again and it comes
> >> up... I tried som copying from another disk and ended up with the disk
> >> all screwed up...
> >>     
> >
> > How that?
> >
> >
> >
> >   
> >> yet the Seagate Seatools for Dos doesnt find any
> >> errors on it;
> >>     
> >
> > There's smartmontools (program: smartctl) for FreeBSD in the ports.
> > It can check various errors of modern hard disks.
> >
> >
> >
> >   
> >> Partition magic found an error but couldn't fix it, so now
> >> Im wiping the whole thing and will try to reinstall tomorrow. Doesn't
> >> make sense.
> >>     
> >
> > What error was this?
> >   
> Something about a boot sector - this is not the first time I have seen
> this identical error but on much older hdd's, though still satas.
> This does make me think that these problems are of hardware origin -
> motherboard or sata connectors - I find they are rather Disneyesque
> (Mickey Mouse) or just plain flimsy.
> 
> Time to hit the sack... another day of computer frustration coming up...
> I'm under pressure to lear Flash and have to set up a reliable server to
> test a site I am designing and setting up. Have to do it myself... can't
> afford about anything today. :-(
> Thanks again for the input.
> 
> 
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