[ale] does DUMP backup only the 'used' HD fraction, OR, the 'entire' HD, blank space and all ?

Thu Mar 1 10:44:43 EST 2012

On Thu, 2012-03-01 at 10:17 -0500, Courtney Thomas wrote:
> On 02/29/12 23:05, Jim Kinney wrote:
> > dump ignores blank space. It's only concerned  with files.
> > Dump will not get the boot sector data.
> >
> > The no label may just be a really old drive or a jumper is set wrong 
> > to turn off LBA.
> >
> > Note: it's not required for  full dump to reset the dump flags. You 
> > can just ignore the flags with dump -level0
> >
> > Master/slave: for performance needs, it;s best to have the source and 
> > target drive on different ATA cables. If they share a cable as 
> > master/slave, it will run at slightly less than 50% the dump speed as 
> > if they were on different cables. It make no different which is master 
> > as long as they are different if on the same cable.
> >
> > I use rsync for this now. Dump is _so_ 1970's :-)
> >
> > On Wed, Feb 29, 2012 at 9:50 PM, Courtney Thomas 
> > <courtneycthomas at bellsouth.net <mailto:courtneycthomas at bellsouth.net>> 
> > wrote:
> >
> >     Greetings Again !
> >
> >     I'm trying to archive a HD to a smaller drive using DUMP, and I'm
> >     OK if it
> >     only archives the written portion of the source drive, but if it
> >     requires that
> >     the 'blank' space also be included, then I guess I'll need to buy a
> >     larger drive.
> >
> >     I'm aware of the chflags nodump capability which'd apparently permit
> >     omitting part of the source of this intended complete backup, i.e.
> >     dump
> >     -0.....
> >
> >     What I seek is a full backup so that I can simply remove a failed
> >     drive,
> >     plug
> >     this one in, and run, essentially as I'm now doing with the source
> >     drive. I've
> >     got months of effort in putting together this drive and I'll shoot
> >     myself if
> >     I don't get it backed up before the inevitable occurs  :-)
> >
> >     --------------------------------------------------------------------------------------------------
> >
> >     Also, the archive drive is a new, but older Seagate (never used),
> >     drive
> >     [ATA]
> >     which I've tested, block by block, [dd] without error, which
> >     partitions and
> >     formats without difficulty, but for unknown reasons, will not permit
> >     labeling.
> >     [R/W DMA error.] Please instruct how to handle this.
> >
> >     --------------------------------------------------------------------------------------------------
> >
> >     Finally, does master/slave jumper matter here ?
> >
> >     --------------------------------------------------------------------------------------------------
> >
> >     All guidance gratefully requested,
> >
> >     Courtney
> >     _______________________________________________
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> >     Ale at ale.org <mailto:Ale at ale.org>
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> >
> >
> >
> >
> > -- 
> > -- 
> > James P. Kinney III
> >
> > As long as the general population is passive, apathetic, diverted to 
> > consumerism or hatred of the vulnerable, then the powerful can do as 
> > they please, and those who survive will be left to contemplate the 
> > outcome.
> > - ////2011 Noam Chomsky
> >
> > http://heretothereideas.blogspot.com/
> > ////
> >
> >
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> Jim,

> As always, thanks for your help.

> What advantages does rsync offer, in terms of what I'm trying to do and 
> what specific command do you recommend in that regard ?

Potentially, several things.

I can't speak authoritatively to the modern "dump" command but the one I
use to work with would literally dump what it found, including
directories.  That meant that it preserved the order of items in the
directory and any holes from deleted items.  I learned this the hard way
after a news system directory exploded on my and I had a huge directory,
even though the news items had been deleted.  Backup obligingly backed
up the massive (but largely deleted) directory and restored the
oversized directory structure.  I had to recreate it manually to get rid
of the cruft.  Older file systems, massive directories could turn in to
huge performance issues.  Newer file systems, not so much but still not
a lot of fun if you can avoid it.  Newer version of dump may avoid this
pitfall, I don't know.

If you get creative with rsync, you can create incremental backups using
the --link-dest option.  Then, the new directory contains the backed up
files but any files that had not changed are hard links back to the
reference directory.  This has a big advantage (to me) over dump because
you've got a complete functional file system structure that that mirrors
the state of the system when you backed it up and you don't have the
problem of restoring from dump files or having to deal with the
incremental dumps.

Your mileage may vary.

Regards,
Mike

> Thank you for your time,

> Courtney

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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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