[9fans] Wipe clean, start over

[9fans] Wipe clean, start over

[Karljurgen Feuerherm]

Hi

After having managed to do an instal on my Toshiba Satellite laptop using 9atom.iso and mucking around for a while (presumably corrupting some things in the process), I'd like to start over from scratch. I.e. totally from scratch as though there had never been any Plan9 on there in the first place.

I've tried various things, such as deleting partitions, reinstalling windows and then reinstalling plan9... but I always seem to end up with some residual stuff (e.g. the users I created the last time around are still there...!)

What would be the fastest and easiest way to accomplish this? Presumably by booting directly from the 9atom disc, and then....?

Many thanks,

K

Re: [9fans] Wipe clean, start over

[Corey]

On Sunday 16 May 2010 3:27:19 Karljurgen Feuerherm wrote:
> I've tried various things, such as deleting partitions, reinstalling
> windows and then reinstalling plan9... but I always seem to end up with
> some residual stuff (e.g. the users I created the last time around are
> still there...!)
>

I can confirm this behavior.  I've seen it many times during my own
repeated installations of plan 9.  Somehow, the plan9-created
partitions/slices are remarkably "sticky"... The data manages to
linger even after deleting and recreating the partition table, and
even after reformatting said new partitions with, say, reiserfs or
ext2/3 from linux.

I found that in order to guarantee an absolute _clean_ re-install of
plan 9, I need to:

* boot into linux w/ a rescue cd
* run 'shred' on the previous plan9-created partition
* delete the partition(s)
* clear the previous plan9-installed MBR with:
dd if=/dev/zero of=/dev/hda bs=512 count=1

... otherwise... the next re-install of plan 9 ends up with data from
the previous install.

This is highly annoying and time-consuming, especially when doing
repeated re-installs for whatever reasons.

Re: [9fans] Wipe clean, start over

[ron minnich]

it's always been sufficient for me to
cat /dev/zero > /dev/sdC0 or whatever. Blowing away the first couple
hundred blocks seems to work fine.

It does go out of its way to try to reuse what partitions it thinks it
finds. but if it's all zeros there you are usually fine.

ron

Re: [9fans] Wipe clean, start over

[John Floren]

On Sun, May 16, 2010 at 6:45 PM, ron minnich <rminnich@gmail.com> wrote:
> it's always been sufficient for me to
> cat /dev/zero > /dev/sdC0 or whatever. Blowing away the first couple
> hundred blocks seems to work fine.
>
> It does go out of its way to try to reuse what partitions it thinks it
> finds. but if it's all zeros there you are usually fine.
>
> ron
>
>

I've also found that, if I don't feel like writing zeroes to the
drive, I can instead shift the start/end locations of the fossil and
venti partitions by 1, which seems to do the trick as well.

John
--
"With MPI, familiarity breeds contempt. Contempt and nausea. Contempt,
nausea, and fear. Contempt, nausea, fear, and .." -- Ron Minnich

Re: [9fans] Wipe clean, start over

[erik quanstrom]

> This is highly annoying and time-consuming, especially when doing
> repeated re-installs for whatever reasons.

i generally just zero out the disk until fossil faults then reboot.
i haven't seen any residual effects.

on the other hand, i never share the disk with linux.

- erik

Re: [9fans] Wipe clean, start over

[erik quanstrom]

On Sun May 16 20:32:50 EDT 2010, kfeuerherm@wlu.ca wrote:
> ok, overriding the installation script and deliberately doing partdisk, prepdisk, and fmtfossil (which warned me that the partition was already properly formatted), seems to have done it, since i got to watch the system copy all the files...
>
> now, if i can only get the disc bootable again... i did tell it to instal the plan9 bootrecord, but to no avail, it seems.
>
> any suggestions? i did try disk/mbr -m /386/mbr /dev/sdC0/data...

is your plan9 partition active?

- erik

Re: [9fans] Wipe clean, start over

[Karljurgen Feuerherm]

ok, overriding the installation script and deliberately doing partdisk, prepdisk, and fmtfossil (which warned me that the partition was already properly formatted), seems to have done it, since i got to watch the system copy all the files...

now, if i can only get the disc bootable again... i did tell it to instal the plan9 bootrecord, but to no avail, it seems.

any suggestions? i did try disk/mbr -m /386/mbr /dev/sdC0/data...

k

>>> "Karljurgen Feuerherm" <kfeuerherm@wlu.ca> 05/16/10 7:58 PM >>>
yes, that's what i would have expected too!

K

>>> ron minnich <rminnich@gmail.com> 05/16/10 7:09 PM >>>
On Sun, May 16, 2010 at 3:59 PM, Karljurgen Feuerherm <kfeuerherm@wlu.ca> wrote:
> well, can't boot from the hard drive (not bootable after all my fiddling, apparently), and if i boot plan9 from the iso and user glenda, it tells me i don't have the permissions to do it. and i don't seem to be able to do cons -l /srv/fscons either (file does not exist...)

That's very odd. If you  boot from the cd, you're the hostowner, and
you should have all the permissions you need to wipe the disk. That's
how I clean them.

ron

Re: [9fans] Wipe clean, start over

[Karljurgen Feuerherm]

yes, that's what i would have expected too!

K

>>> ron minnich <rminnich@gmail.com> 05/16/10 7:09 PM >>>
On Sun, May 16, 2010 at 3:59 PM, Karljurgen Feuerherm <kfeuerherm@wlu.ca> wrote:
> well, can't boot from the hard drive (not bootable after all my fiddling, apparently), and if i boot plan9 from the iso and user glenda, it tells me i don't have the permissions to do it. and i don't seem to be able to do cons -l /srv/fscons either (file does not exist...)

That's very odd. If you  boot from the cd, you're the hostowner, and
you should have all the permissions you need to wipe the disk. That's
how I clean them.

ron

Re: [9fans] Wipe clean, start over

[ron minnich]

On Sun, May 16, 2010 at 3:59 PM, Karljurgen Feuerherm <kfeuerherm@wlu.ca> wrote:
> well, can't boot from the hard drive (not bootable after all my fiddling, apparently), and if i boot plan9 from the iso and user glenda, it tells me i don't have the permissions to do it. and i don't seem to be able to do cons -l /srv/fscons either (file does not exist...)

That's very odd. If you  boot from the cd, you're the hostowner, and
you should have all the permissions you need to wipe the disk. That's
how I clean them.

ron

Re: [9fans] Wipe clean, start over

[Karljurgen Feuerherm]

well, can't boot from the hard drive (not bootable after all my fiddling, apparently), and if i boot plan9 from the iso and user glenda, it tells me i don't have the permissions to do it. and i don't seem to be able to do cons -l /srv/fscons either (file does not exist...)

K

>>> ron minnich <rminnich@gmail.com> 05/16/10 6:46 PM >>>
it's always been sufficient for me to
cat /dev/zero > /dev/sdC0 or whatever. Blowing away the first couple
hundred blocks seems to work fine.

It does go out of its way to try to reuse what partitions it thinks it
finds. but if it's all zeros there you are usually fine.

ron