Re: Resize a disk image from 32G to 4G or copy u-boot?
On Wednesday 25 March 2020 08:51:17 grumpy@mailfence.com wrote:
> On Wed, 25 Mar 2020, Gene Heskett wrote:
> > On Wednesday 25 March 2020 04:18:20 Andrei POPESCU wrote:
> >> On Ma, 24 mar 20, 19:12:46, Gene Heskett wrote:
> >>> And nothing so far, and I have been watching, in the way of
> >>> reducing a filesystem to only the actual size occupied. Then it
> >>> can be backed up with dd and recovered, rewritten by dd, at a
> >>> reasonable size for storage. And re-expanded to fit the media it
> >>> finds.
> >>
> >> You could do this with the 'sparse' option of dd (you might need to
> >> fill the partition with a file containing only zeroes first).
> >>
> >> The resulting file must be handled with care as many tools (cp,
> >> rsync) will un-sparse it by default, as will writing it to a
> >> filesystem without support for sparse files (tar it first).
> >>
> >> To see the actual size with ls you will have to use -s/--size.
> >>
> >>> All of my attempts to do that with dd alone have been thwarted by
> >>> the fact that I have yet to find two u-sd's marked as such and
> >>> such a capacity, that actually were the same size.
> >>
> >> Just create the partitions slightly smaller than the size of the SD
> >> card.
> >
> > I've also considered that, but then you risk losing the gpt tables
> > and it all disappears in the cloud of blue smoke being emmited from
> > ones ears.
> >
> > BTDT at least twice on arm systems. The distro folks have it and use
> > it to make an install image of 5 gigs, unpacks to 7 or 8G and which
> > can then be auto expanded on the first reboot to fill the card, so
> > they know how to do it, why can't the user make backups from a
> > deployed well running system that could be put on a fresh u-sd card
> > and treated exactly the same for recovery purposes?
>
> could you not just dd to a file and then manipulate that file to suit
> you but i would never dd a running system
Amanda has very occassional problems with that as all its backups are
from a live system.
Cheers, Gene Heskett
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