[Bradford] Formatting micro SD for Raspberry Pi

[David Spencer]

Hi folks

It is a *terrible* *terrible* *terrible* idea to "clean" SD cards in
this way. They have a limited number of write cycles. You're just
destroying the card for no benefit. Same goes for any other flash
based tech -- old USBs, eMMC, ssd, nvme.

If you have a used SD card and you want a complete re-do, start with
dd'ing the os image again. Pre-zeroing the whole thing with dd before
that is simply using up all the write cycles for nothing and likely to
end in an unusable card.

Cheers
-D.

On Tue, 16 Mar 2021 at 17:09, Moanin via Bradford
<bradford at mailman.lug.org.uk> wrote:
>
> Hi Folks,
>
> Seems it's all done, using dd on the command line. The only mistake was
> neglecting to add an empty ssh file in the boot partition so "access
> denied" errors ensued 'til I managed to work it out. The info was tucked
> away in a "locked" corner of the forum.
>
> Just as importantly, the whole micro sd card is usable. There are 29
> gigs instead of 4.
>
> Raspberry OS is Debian. I don't like having sudo by default. It allows
> any intruder to test it out. Far better to have shell only access for a
> user and force use of su with a strong password for root.
>
> Still, I can sort that out later. It's just great to have a minimal
> install of any distro and space to work in. Now to enable wireless and
> move it from its precarious position on the windowsill!
>
> Thanks for all the help and ideas, including those off-list.
>
> Cheers,
>
> Mike
>
>
> On 16/03/2021 12:11, Bernard Czenkusz via Bradford wrote:
> > Hi guys
> >
> > For what its worth:
> >
> > With Linux Mint I used the  graphical 'Disks' option, with menu
> > description 'Manage Drives and Media' - then within the application I
> > highlighted the (unmounted) card and from the utilities hamburger menu
> > chose the 'Restore Disk Image..'  option, chose the image file, and it
> > loaded the image. From memory, I don't think there was any need to
> > format.
> >
> > I find the 'Disks' menu calls the command "gnome-disks" which is
> > widely available, you may already have it. Though its only applicable
> > if you're using a graphical desktop.
> >
> > Cheers
> >
> >  Bernard
> >
> >
> > On 15/03/2021 22:50, Moanin via Bradford wrote:
> >> Hi John,
> >>
> >> That's got me perplexed! Is the 32768 the bs=1M multiple? Each time
> >> an SD card is formatted it loses some space. These two are now down
> >> to 29.??gb (the older one) and 31.?? (the new one). Which raises the
> >> question: do we need to stipulate the size, or, as I suspect, isn't
> >> it just as good to let whichever utility supply a default, which
> >> should be the end of the disc?
> >>
> >> Alternatively, is 32768 the number of blocks in a section? That
> >> amounts to 4gb and is the size of the sections which were causing the
> >> problems earlier.
> >>
> >> Or does 32768 simply state a maximum limit for the dd command?
> >>
> >> The original dd command was:
> >>
> >> dd if=/dev/zero of=/dev/sdb bs=1M status=progress
> >> which gave me a constant update of, well, progress.
> >>
> >> Now this has popped up in the browser (well I did do a search):
> >> https://www.iottechtrends.com/format-sd-card-for-raspberry-pi/
> >> the implication of which appears to be that the dd command for
> >> installing the image will implement the partitioning, too.
> >>
> >> That looks attractive, in part because of its simplicity. It also
> >> shows me that I neglected to unmount the card before formatting it
> >> during the earlier efforts.
> >>
> >> But will it work? It implies using dd for the whole process.
> >>
> >> TIA,
> >>
> >> Mike
> >>
> >> On 15/03/2021 22:02, John Robert Hudson wrote:
> >>> Hi Mike
> >>>
> >>>
> >>> With a 32GB card you should be using something like:
> >>>
> >>>
> >>> dd if=/dev/zero of=/dev/sdb bs=1M count=32768
> >>>
> >>>
> >>> The DOS partition is presumably for /boot/efi and the Ext4
> >>> partitions for / and /home - no swap?
> >>>
> >>>
> >>> I would use Gparted for that.
> >>>
> >>>
> >>> John
> >>>
> >>>
> >>> On Monday, 15 March 2021 21:08:44 GMT Moanin via Bradford wrote:
> >>>
> >>>  > Evenin' All,
> >>>
> >>>  >
> >>>
> >>>  > I have two 32gb micro SD cards, the second because the first one
> >>>
> >>>  > appeared to be corrupted. Once loaded with an OS, there were
> >>> loads of
> >>>
> >>>  > 4gb sectors at the beginning and the OS update in the Pi showed not
> >>>
> >>>  > enough space left on the card. It needed a few more mb on the
> >>> partition.
> >>>
> >>>  > But it wasn't the card. This has repeated itself with each
> >>> attempt to
> >>>
> >>>  > fix matters.
> >>>
> >>>  >
> >>>
> >>>  > Wiping the cards then checking with either lsblk or fdisk -l
> >>> showed them
> >>>
> >>>  > as clean. So the formatting process came under suspicion and I
> >>> was extra
> >>>
> >>>  > careful when formatting them. So the OS transfer (using dd)
> >>> became the
> >>>
> >>>  > main suspect.
> >>>
> >>>  >
> >>>
> >>>  > They wee cleaned using the command "dd if=/dev/zero of=/dev/sdb
> >>> bs=8192"
> >>>
> >>>  > (earlier attempts were with bs=1M) and everything shows as 512 bytes
> >>>
> >>>  > from fdisk -l /dev/sdb. The result has not changed with the
> >>> altering of
> >>>
> >>>  > the bs size parameter. It looks OK to me. Is it correct? As we
> >>> would expect?
> >>>
> >>>  >
> >>>
> >>>  > All of the above was using a CentOS 7 for Pi download but it may be
> >>>
> >>>  > corrupted (the cause) and no Pi version is available any more. So
> >>>
> >>>  > Raspberry Pi OS (Raspbian has been renamed, still Debian based)
> >>> is about
> >>>
> >>>  > to be downloaded.
> >>>
> >>>  >
> >>>
> >>>  > Here's the question: what is the best format structure for one of
> >>> these
> >>>
> >>>  > micro SDs prior to installing it? I really don't want to end up
> >>> going
> >>>
> >>>  > round in more frustrating and time consuming circles.
> >>>
> >>>  >
> >>>
> >>>  > The various online docs show a dos partition table with a 512M ext4
> >>>
> >>>  > primary partition and another ext4 primary partition for the
> >>> remainder
> >>>
> >>>  > of the card. I've been using fdisk to do the formatting. Would
> >>> Parted do
> >>>
> >>>  > a better job, or stick with fdisk?
> >>>
> >>>  >
> >>>
> >>>  > If fdisk and dos table, is it safe to just hit o (create a new
> >>> empty dos
> >>>
> >>>  > partition table) to begin with?
> >>>
> >>>  >
> >>>
> >>>  > TIA,
> >>>
> >>>  >
> >>>
> >>>  > Mike
> >>>
> >>>  >
> >>>
> >>>  > --
> >>>
> >>>  > Bradford mailing list
> >>>
> >>>  > Bradford at mailman.lug.org.uk
> >>>
> >>>  > https://mailman.lug.org.uk/mailman/listinfo/bradford
> >>>
> >>>
> >>>
> >>
> >
>
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