Re: need sd card backup on r-pi-3b
On Saturday 23 September 2017 07:43:14 Jonathan Wilson wrote:
> On Fri, 2017-09-22 at 22:07 -0400, Gene Heskett wrote:
> > Greetings;
> >
> > Trying to dd a copy of the micro-sd card the pi-3b is booting from,
> > to another micro-sd card in a usb reader/writer, and winding up with
> > nothing but an empty lost+found directory on it.
> >
> > Obviously some sort of a syntax error, but it still takes the pi
> > several hours to do it, with the traffic led on the reader/writer
> > showing continuous activity.
> >
> > Is there another way/util that actually works for making verbatim
> > backups of these limited lifetime sd cards?
> >
> > Thanks.
> >
> > Cheers, Gene Heskett
>
> I used to use dd quite a lot, usually to a file (from a disk) as I was
> playling with virtual boxes quite a bit. It "may" be that the dd is
> not from the disk, but is from a partition... or some other variation
> on the theme (1). Also, its worth typing sync after the dd to make
> sure that all disk access (write) is coalesced. If I recall correctly,
> once the sync returns to the command line then there are no more
> pending writes so even pulling the SD (not correctly
> un-mounting/ejecting it) shouldn't corrupt it.
>
All followed and understood.
>
> (1) When dd'ing between physical drives I always made sure they were
> matched size wise, which was probably not required but I had it in my
> head that dd'ing a drive including the partition table to a larger
> sized drive would cause issues. Where the drives were unmatched I'd
> set the new partition(s) manually, and then dd the partitions one at a
> time and I always made sure the too partition was set up to be the
> same size as the from partition (even if the location differed) and
> then do any re-sizing of the cloned partition & file system upwards
> afterwards. As I say, possibly not required in some/all cases but gut
> feelings are hard to overcome as I had it in my head - something to do
> with backup tables set at the far end of partitions.
humm... backup inodes are generally at 8k offsets from the starters
location, or so I've read.
And why, when I click on reply to list, do I get blank to: lines and have
to manually copy them from the incoming email? Its a right pita.
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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