How to rescue your partitions after upgrade to Fedora 18 Alpha eats them
 

Eddie G. O'Connor Jr. wrote:

On 09/23/2012 07:22 PM, Roger wrote:

On 09/24/2012 02:09 AM, Eddie G. O'Connor Jr. wrote:

On 09/23/2012 07:33 AM, Jakub Kicinski wrote:

Hi all,

I recently had a weird problem after "upgrade" to Fedora 18 Alpha. I
decided to share the solution, maybe it will help someone.

But first:

1. The rant

Clearly something bad is going on in Fedora world. I've been
upgrading to Alphas/Betas for years now and it never caused more
trouble than occasional need to rebuild some packages manually.

I read this:
http://lwn.net/Articles/506831/
but I didn't suspect that not only Rawhide, but also Alpha releases
became unusable.

First of all PreUpgrade crashes before it starts. I thought, well, I'll
try DVD. It kind of worked. I was looking for words like "upgrade" or
"update" in the new and shiny anaconda but no luck. Eventually it
started the installation (without any "Warning: write changes to
disk?" or alike). At that point partitions of Fedora 17 where already
magically renamed to Fedora 18, so I hoped for the best. Unfortunately
anaconda crashed when it tried to format my Win7 partition to the
widely used filesystem "None"?! Imagine my amusement when after reboot
I realised that MBR and GPT where wiped out and all of my partitions
were nowhere to be found.

2. The problem

It turned out anaconda not only wipes out MBR but also removes magic
numbers from partitions superblocks (anyone can explain why?). So the
good news was my data was still there, the bad news was: none of
automatic "lost partition detection" tool could find them (at least none
that I know of).

3. The solution

If it happens to you as well, here is what you can try to get your
data back:

a. Accept that you do all this on your own risk ;)
b. Backup your HDD, preferably all of it. Backup can be done with dd.
c. Connect damaged HDD to some other Linux box or use a Live
distribution.
d. Now you need to locate your first partition. There is a good chance
that this will be your /boot and Fedora usually locates it at
0x100000 (i.e. it starts in 2048 sector). Other possibility is
sector 63/64 from pre-GPT world.
e. Set magic value in superblock (see below).
f. Try mounting partition using offset option in mount.
g. Calculate where next partition is most likely to start using block
count and block size from superblock.
h. Fix your MBR. You can probably do that in parted or some similar
tool, but who would trust tools after one just nearly destroyed all
your data.
i. If you have more partitions to find, go back to (d).


Important: All values on disk are LITTLE ENDIAN.
Important: Try mounting your partitions read-only first.

Notes on EXT4.
Ext4 is quite easy to find. You will recognize it by two zeroed out
sectors (1024 bytes of zeroes) at the beginning of every partition.
NOTE: those zeroes are *in* the partition, do not skip them when trying
to mount. After zeroes there is a superblock. What you are looking
for is offset +0x38 in the superblock, where you once had a magic value
of 0xEF53, you will probably have to put it back there. More information
on EXT4:
https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout

Notes on NTFS.
NTFS partition starts with EB 52 90, there are no zeroes in front. Magic
value which is removed by anaconda is "4E 54 46 53 20 20 20 20"
at offset 0x03 into a partition. Its literally "NTFS " (with spaces).
More info:
http://technet.microsoft.com/en-us/library/cc781134%28v=ws.10%29.aspx

Useful tools:
dd - will help you to copy blocks of data around. If you don't know it
already, I advise you to read some tutorial and practise first. It's
easy to destroy thing with one wrong dd.

emacs, okteta etc. - hex editor...

losetup - is a tool which enables you to mount files and drives at
particular offset as loop devices. Very useful, read more here:
http://rackerhacker.com/2010/12/14/mounting-a-raw-partition-file-made-with-dd-or-dd_rescue-in-linux/

dumpe2fs, nftsinfo - will decode superblock for you.

bash calculator - $((1+2+3+4*4)) can save you a lot of time.
bash printf - printf "%d
" 0x1AB2F or printf "%x
" $((7863*4096)) is
handy as well.

Good luck from (a sightly less happy) Fedora user
-- Kuba

WOW!.....that's terrible! But I guess that's just one of the reasons I
purposely wait until a release has been out for almost 3 months....before
installing / upgrading. It just makes it a little easier when the glitches
have been made apparent and are either completely worked out or are in the
process of being worked out. In all honesty...I actually prefer to wait a few
releases before upgrading, I kind of have my OWN "schedule" I usually wait
and let one release pass by, then I'll wait for the next version...and 3 to 4
months into _that _I'll upgrade.....this helps me remain a little more
"stable" and not have to scurry around upgrading every 6 months....


EGO II



Yes I am much the same. I'll skip an upgrade or two, wait for stability then
after copying all my files, do a fresh install.
Roger



It just seems that.....of all the different methods....THAT one is the safest.
I've accumulated quite a few "irreplaceable" files throughout the years...and
I'd hate to lose some or all of them due to a restructuring of the build for the
installer!..

I invested in a Blu-Ray drive and a few blanks, in conjunction with dvdisaster I
can back up 20GB of data with three levels of error recovery, on a media which
is not subject to vibration or shock damage (within any reasonable limits),
water resistant, and immune to magnetic damage and EMP. Stored off-site one disk
covers all of my "really critical" data.


Investment is <$100 if you shop carefully.

--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
--
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How to rescue your partitions after upgrade to Fedora 18 Alpha eats them
 

Eddie G. O'Connor Jr. wrote:

On 09/23/2012 07:33 AM, Jakub Kicinski wrote:

Hi all,

I recently had a weird problem after "upgrade" to Fedora 18 Alpha. I
decided to share the solution, maybe it will help someone.

But first:

1. The rant

Clearly something bad is going on in Fedora world. I've been
upgrading to Alphas/Betas for years now and it never caused more
trouble than occasional need to rebuild some packages manually.

I read this:
http://lwn.net/Articles/506831/
but I didn't suspect that not only Rawhide, but also Alpha releases
became unusable.

First of all PreUpgrade crashes before it starts. I thought, well, I'll
try DVD. It kind of worked. I was looking for words like "upgrade" or
"update" in the new and shiny anaconda but no luck. Eventually it
started the installation (without any "Warning: write changes to
disk?" or alike). At that point partitions of Fedora 17 where already
magically renamed to Fedora 18, so I hoped for the best. Unfortunately
anaconda crashed when it tried to format my Win7 partition to the
widely used filesystem "None"?! Imagine my amusement when after reboot
I realised that MBR and GPT where wiped out and all of my partitions
were nowhere to be found.

2. The problem

It turned out anaconda not only wipes out MBR but also removes magic
numbers from partitions superblocks (anyone can explain why?). So the
good news was my data was still there, the bad news was: none of
automatic "lost partition detection" tool could find them (at least none
that I know of).

3. The solution

If it happens to you as well, here is what you can try to get your
data back:

a. Accept that you do all this on your own risk ;)
b. Backup your HDD, preferably all of it. Backup can be done with dd.
c. Connect damaged HDD to some other Linux box or use a Live
distribution.
d. Now you need to locate your first partition. There is a good chance
that this will be your /boot and Fedora usually locates it at
0x100000 (i.e. it starts in 2048 sector). Other possibility is
sector 63/64 from pre-GPT world.
e. Set magic value in superblock (see below).
f. Try mounting partition using offset option in mount.
g. Calculate where next partition is most likely to start using block
count and block size from superblock.
h. Fix your MBR. You can probably do that in parted or some similar
tool, but who would trust tools after one just nearly destroyed all
your data.
i. If you have more partitions to find, go back to (d).


Important: All values on disk are LITTLE ENDIAN.
Important: Try mounting your partitions read-only first.

Notes on EXT4.
Ext4 is quite easy to find. You will recognize it by two zeroed out
sectors (1024 bytes of zeroes) at the beginning of every partition.
NOTE: those zeroes are *in* the partition, do not skip them when trying
to mount. After zeroes there is a superblock. What you are looking
for is offset +0x38 in the superblock, where you once had a magic value
of 0xEF53, you will probably have to put it back there. More information
on EXT4:
https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout

Notes on NTFS.
NTFS partition starts with EB 52 90, there are no zeroes in front. Magic
value which is removed by anaconda is "4E 54 46 53 20 20 20 20"
at offset 0x03 into a partition. Its literally "NTFS " (with spaces).
More info:
http://technet.microsoft.com/en-us/library/cc781134%28v=ws.10%29.aspx

Useful tools:
dd - will help you to copy blocks of data around. If you don't know it
already, I advise you to read some tutorial and practise first. It's
easy to destroy thing with one wrong dd.

emacs, okteta etc. - hex editor...

losetup - is a tool which enables you to mount files and drives at
particular offset as loop devices. Very useful, read more here:
http://rackerhacker.com/2010/12/14/mounting-a-raw-partition-file-made-with-dd-or-dd_rescue-in-linux/

dumpe2fs, nftsinfo - will decode superblock for you.

bash calculator - $((1+2+3+4*4)) can save you a lot of time.
bash printf - printf "%d
" 0x1AB2F or printf "%x
" $((7863*4096)) is
handy as well.

Good luck from (a sightly less happy) Fedora user
-- Kuba

WOW!.....that's terrible! But I guess that's just one of the reasons I purposely
wait until a release has been out for almost 3 months....before installing /
upgrading. It just makes it a little easier when the glitches have been made
apparent and are either completely worked out or are in the process of being
worked out. In all honesty...I actually prefer to wait a few releases before
upgrading, I kind of have my OWN "schedule" I usually wait and let one release
pass by, then I'll wait for the next version...and 3 to 4 months into _that
_I'll upgrade.....this helps me remain a little more "stable" and not have to
scurry around upgrading every 6 months....

I followed FC from 4->6->9->13->16->17, generally updating when a security issue
popped up I didn't want to patch myself. The 16->17 was because of the kernel,
too much good stuff added to miss on my VM hosting servers. Building new kernels
and keeping the associated files current takes too much time.



--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
--
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How to rescue your partitions after upgrade to Fedora 18 Alpha eats them
 

On Tue, 2012-09-25 at 01:31 +0100, Ian Malone wrote:
> On 25 September 2012 00:55, Joe Zeff <joe@zeff.us> wrote:
> > On 09/24/2012 04:44 PM, Jakub Kicinski wrote:
> >>
> >> On Mon, 24 Sep 2012 08:09:11 -0430, Patrick O'Callaghan
> >> <pocallaghan@gmail.com> wrote:
> >>
> >>> >On Sun, 2012-09-23 at 13:33 +0200, Jakub Kicinski wrote:
> >>>>
> >>>> >>I recently had a weird problem after "upgrade" to Fedora 18 Alpha. I
> >>>> >>decided to share the solution, maybe it will help someone.
> >>>
> >>> >
> >>> >This should be posted to the Fedora test list, not here. F18 is not a
> >>> >released system.
> >>
> >> Sorry, won't happen again.
> >
> >
> > Please don't think you've offended us, Kuba, or that we want you to go away
> > and stay there. It's just that in this case, you asked a question that
> > we're really not qualified to answer, so Patrick pointed you in the right
> > direction.
> >
> > And, there's no reason to sign off of the list if you haven't already done
> > so. It won't be too long before F18 has its coming out party, making it
> > very appropriate for this list.
>
> Actually, I think it's worth having this mentioned on this list. The
> problem (F18 alpha will eat your data) is fairly well known on the
> devel list, but the fact that Jakub thought this needed a post
> suggests that people on the users list aren't aware of it at a time at
> which they might start trying Alpha. So starting a 'here be dragons'
> thread is not completely unwarranted. (Also a bit extreme to say we
> absolutely cannot mention F18 here when the assumption on devel is
> often that you are a maintainer or developer, this is the users list
> after all.)

None of these lists have rigid rules, but they do have community
guidelines. Keeping discussion of unreleased development versions to the
Test list is a sensible example. My take on Jakub's post is that he was
unaware of the Test list until it was pointed out to him. Someone who's
going to be trying out F18 at this stage (it's still months from
release) really needs to get on the list that's specifically for devels
*and testers* or they're going to have a frustrating time of it.

poc

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