I have several rather complex debian systems, including software raid 5
and lvm, &c.

Occasionally, in the past, I have upgraded a debian system, after which
it no longer boots successfully. Unfortunately, for these complex
systems, neither the install/boot media, nor knoppix, result in access
to the files necessary to recover these systems.

So, going forward, I want to incorporate generation of bootable rescue
cd's into my upgrade processes. Clearly, such a cd will exactly
duplicate my last successful boot, and give access to ALL files and
filesystems.

[1] What is the simplest & most reliable process for creating such a cd?

[2] Upgrading WHICH packages should be followed by creating such cd?
Obviously, upgrading vim itself is NOT likely to jeopardize my next
boot; but, the kernel, some libraries, and some packages involved in the
early boot stages, are possible culprits.

What do you do?

What do you think?

--
Best Regards,

helices
-
Dare to fix things before they break . . .
-
Our capacity for understanding is inversely proportional to how much
we think we know. The more I know, the more I know I don't know . . .
--

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On Fri, 28 Sep 2007 17:27:02 -0500
helices <helices@helices.org> wrote:


> What do you do?
>


If you are looking at just recovering a system that won't boot, you
don't need a specific Debian disk to do it. I usually carry a copy of
the System Rescue CD (http://www.sysresccd.org/Main_Page). It has all
of the tools I need to recover a downed system. If I need to work on
the Debian system itself, I mount the drive and chroot into the
partition. Once there I can su to root so that I am using the proper
Debian environment, run apt-get to update software, and test the
configuration of any of the installed services or utilities.

Why re-invent the wheel?

- --
Bill Thompson
BillT@Mahagonny.com
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On Fri, 28 Sep 2007 17:27:02 -0500
helices <helices@helices.org> wrote:

> What do you do?
>

If you are looking at just recovering a system that won't boot, you
don't need a specific Debian disk to do it. I usually carry a copy of
the System Rescue CD (http://www.sysresccd.org/Main_Page). It has all
of the tools I need to recover a downed system. If I need to work on
the Debian system itself, I mount the drive and chroot into the
partition. Once there I can su to root so that I am using the proper
Debian environment, run apt-get to update software, and test the
configuration of any of the installed services or utilities.

Why re-invent the wheel?


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* Bill Thompson <Billt@Mahagonny.com> [2007:09:28:16:18:26-0700] scribed:
> On Fri, 28 Sep 2007 17:27:02 -0500
> helices <helices@helices.org> wrote:
>
> > What do you do?
> >
>
> If you are looking at just recovering a system that won't boot, you
> don't need a specific Debian disk to do it. I usually carry a copy of
> the System Rescue CD (http://www.sysresccd.org/Main_Page). It has all
> of the tools I need to recover a downed system. If I need to work on
> the Debian system itself, I mount the drive and chroot into the
> partition. Once there I can su to root so that I am using the proper
> Debian environment, run apt-get to update software, and test the
> configuration of any of the installed services or utilities.
>
> Why re-invent the wheel?

Well, because the two (2) systems on which I have experienced these --
to me -- insurmountable boot problems were running lvm on top of
software raid 5. I was NOT able to get to the root filesystem files
using debian rescue cd nor knoppix. Both times this happened, it had
something to do with initramfs; but, after many, many days of struggle,
it became easier to rebuild from scratch, and to restore specifics on
top of that from tape.

What am I missing?

--
Best Regards,

helices
-
Dare to fix things before they break . . .
-
Our capacity for understanding is inversely proportional to how much
we think we know. The more I know, the more I know I don't know . . .
--

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On Fri, 2007.09.28 21:25, helices wrote:
> Bill Thompson <Billt@Mahagonny.com> [2007:09:28:16:18:26-0700] scribed:
> > If you are looking at just recovering a system that won't boot, you
> > don't need a specific Debian disk to do it. I usually carry a copy of
> > the System Rescue CD (http://www.sysresccd.org/Main_Page). It has all
> > of the tools I need to recover a downed system. If I need to work on
> > the Debian system itself, I mount the drive and chroot into the
> > partition. Once there I can su to root so that I am using the proper
> > Debian environment, run apt-get to update software, and test the
> > configuration of any of the installed services or utilities.
> >
> > Why re-invent the wheel?
>
> Well, because the two (2) systems on which I have experienced these --
> to me -- insurmountable boot problems were running lvm on top of
> software raid 5. I was NOT able to get to the root filesystem files
> using debian rescue cd nor knoppix. Both times this happened, it had
> something to do with initramfs; but, after many, many days of struggle,
> it became easier to rebuild from scratch, and to restore specifics on
> top of that from tape.

When I started using encryption, I was concerned about having access to the
data easily in the case of a broken system. I wanted a rescue/live CD that
would provide all the necessary Debian tools similarly enough that I could
easily rescue my data using it if necessary. What I now use primarily is GRML
from http://www.grml.org ; it is closely based on Debian, such that it actually
resembles Debian (contrasted with Knoppix which, as far as I know, does not
resemble Debian and is not really compatible with Debian's packages) and
includes many Debian packages. As I see it: if you manage to set somethingup
using Debian, GRML ought to work with it too without any problems.

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On 09/28/2007 09:25 PM, helices wrote:
> * Bill Thompson <Billt@Mahagonny.com> [2007:09:28:16:18:26-0700] scribed:
>> On Fri, 28 Sep 2007 17:27:02 -0500
>> helices <helices@helices.org> wrote:
>>
>>> What do you do?
>>>
>> If you are looking at just recovering a system that won't boot, you
>> don't need a specific Debian disk to do it. I usually carry a copy of
>> the System Rescue CD (http://www.sysresccd.org/Main_Page). It has all
>> of the tools I need to recover a downed system. If I need to work on
>> the Debian system itself, I mount the drive and chroot into the
>> partition. Once there I can su to root so that I am using the proper
>> Debian environment, run apt-get to update software, and test the
>> configuration of any of the installed services or utilities.
>>
>> Why re-invent the wheel?
>
> Well, because the two (2) systems on which I have experienced these --
> to me -- insurmountable boot problems were running lvm on top of
> software raid 5. I was NOT able to get to the root filesystem files
> using debian rescue cd nor knoppix. Both times this happened, it had
> something to do with initramfs; but, after many, many days of struggle,
> it became easier to rebuild from scratch, and to restore specifics on
> top of that from tape.
>
> What am I missing?
>

I don't know, but you might try Bill Thompson's suggestion of System
Rescue CD as well as the new Knoppix CD, 5.1.1.

As far as initramfs is concerned, I suggest removing it from the
equation by compiling a kernel with everything you need to access the
disk built directly into the kernel; don't rely on an initrd at all.

To attempt to answer your first question, I'll say "look at the Debian
Installer." You can probably create a specialized installer CD for your
environment; however this is much harder than using a Knoppix CD.

To attempt to answer your second question, I'll say "talk to the Debian
Installer developers." Finding out what parts of the installer CD need
to be updated when the O/S is updated is complicated enough to require
the input of the experts.

Now I have a few questions:

What version of Knoppix failed for you before?

Do you have a separate /boot partition that is on a filesystem that Grub
can recognize? Read the document "info grub intro features" to get a
list of supported filesystems.

If /boot is on a Grub-supported filesystem/partition, is the initial
root disk on that partition?

Is /boot on an lvm volume? (Probably not, because the system wouldn't boot.)


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On Fri, Sep 28, 2007 at 05:27:02PM -0500, helices wrote:

> So, going forward, I want to incorporate generation of bootable rescue
> cd's into my upgrade processes. Clearly, such a cd will exactly
> duplicate my last successful boot, and give access to ALL files and
> filesystems.
>
> [1] What is the simplest & most reliable process for creating such a cd?

I'm not sure how simple it is, but you should have a look at Live Debian
(http://debian-live.alioth.debian.org/). The project provides prebuilt
images, but you can also build your own and it uses only standard Debian
packages.

Regards,
Andrei
--
If you can't explain it simply, you don't understand it well enough.
(Albert Einstein)

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Thank you, all, for your insights.

When I composed the first message, I had in mind the olden days when I
often (not always ;<) made a bootable floppy when I made a new kernel.
That bootable floppy booted off of the exact same kernel, except a
different copy residing on the floppy. When the system completed boot,
I was logging into the actual system, even though I booted off of the
floppy based kernel.

The problem with knoppix cd, and the debian installation/rescue cd, is
that they do NOT understand the specifics of my lvm over software raid
5. The specifics required probably all reside under /etc -- on a
filesystem in lvm on software raid 5.

Actually, I believe that both instances that stung me were lilo, not
grub; and, NO, there is no /boot outside of both lvm and software raid
5.

What do you think?

--
Best Regards,

helices
-
Dare to fix things before they break . . .
-
Our capacity for understanding is inversely proportional to how much
we think we know. The more I know, the more I know I don't know . . .
--

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On Sat, Sep 29, 2007 at 07:37:10PM -0500, helices wrote:
>
> When I composed the first message, I had in mind the olden days when I
> often (not always ;<) made a bootable floppy when I made a new kernel.
> That bootable floppy booted off of the exact same kernel, except a
> different copy residing on the floppy. When the system completed boot,
> I was logging into the actual system, even though I booted off of the
> floppy based kernel.
>
> The problem with knoppix cd, and the debian installation/rescue cd, is
> that they do NOT understand the specifics of my lvm over software raid
> 5. The specifics required probably all reside under /etc -- on a
> filesystem in lvm on software raid 5.
>
> Actually, I believe that both instances that stung me were lilo, not
> grub; and, NO, there is no /boot outside of both lvm and software raid
> 5.
>

So you're saying that you have an LVM over raid5 setup that Etch's
install CD in rescue mode can't detect and setup?

I didn't know that GRUB can handle LVM or raid5 reliably? Why not use a
32 MB /boot raid1 partition? This may be why the rescue CD can't handle
it.

Doug.


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On 09/29/2007 07:37 PM, helices wrote:
> Thank you, all, for your insights.
>
> When I composed the first message, I had in mind the olden days when I
> often (not always ;<) made a bootable floppy when I made a new kernel.
> That bootable floppy booted off of the exact same kernel, except a
> different copy residing on the floppy. When the system completed boot,
> I was logging into the actual system, even though I booted off of the
> floppy based kernel.
>
> The problem with knoppix cd, and the debian installation/rescue cd, is
> that they do NOT understand the specifics of my lvm over software raid
> 5. The specifics required probably all reside under /etc -- on a
> filesystem in lvm on software raid 5.
>

Catch-22

However, if you read the documents on how they created the Debian
installer, you could find out how to create your own Debian Installer
CD; it would contain your own custom-compiled kernel and lvm
configuration in /etc, and it would be able to see all of your
volumes--that is what you want--right?

> Actually, I believe that both instances that stung me were lilo, not
> grub; and, NO, there is no /boot outside of both lvm and software raid
> 5.
>
> What do you think?
>

I don't know what to think.

Since Etch's Grub supposedly doesn't understand lvm, I can't see how you
booted in the first place.



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helices wrote:
> I have several rather complex debian systems, including software raid 5
> and lvm, &c.
>
> Occasionally, in the past, I have upgraded a debian system, after which
> it no longer boots successfully. Unfortunately, for these complex
> systems, neither the install/boot media, nor knoppix, result in access
> to the files necessary to recover these systems.
>
> So, going forward, I want to incorporate generation of bootable rescue
> cd's into my upgrade processes. Clearly, such a cd will exactly
> duplicate my last successful boot, and give access to ALL files and
> filesystems.
>
> [1] What is the simplest & most reliable process for creating such a cd?
>
>
> What do you do?
>
> What do you think

Before proceeding with major upgrades, I boot with Clonezilla
(http://clonezilla.sourceforge.net/download/sourceforge/) and I create
an image of the hard disk. This image is written to an external USB hard
disk. Should anything goes funny after the upgrade, I can always revert
to the state before the upgrade...

G.


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On Sat, Sep 29, 2007 at 07:37:10PM -0500, helices <helices@helices.org> was heard to say:
> The problem with knoppix cd, and the debian installation/rescue cd, is
> that they do NOT understand the specifics of my lvm over software raid
> 5. The specifics required probably all reside under /etc -- on a
> filesystem in lvm on software raid 5.

Are you sure this is the case? Software raid and LVM are both kernel
things (with userland support utilities), and they're autodetected using
magic numbers on the partitions. As long as the kernel is compiled with
support, I'd expect them to be accessible. It might be that the
autodetection just isn't running on startup; I wonder if some work with
mdadm and the LVM utilities would get you access to the volumes. It might
at least be worth a try.

Daniel


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On Oct 3, 2007, at 6:03 PM, Daniel Burrows wrote:

> On Sat, Sep 29, 2007 at 07:37:10PM -0500, helices
> <helices@helices.org> was heard to say:
>> The problem with knoppix cd, and the debian installation/rescue
>> cd, is
>> that they do NOT understand the specifics of my lvm over software
>> raid
>> 5. The specifics required probably all reside under /etc -- on a
>> filesystem in lvm on software raid 5.
>
> Are you sure this is the case? Software raid and LVM are both
> kernel
> things (with userland support utilities), and they're autodetected
> using
> magic numbers on the partitions. As long as the kernel is compiled
> with
> support, I'd expect them to be accessible. It might be that the
> autodetection just isn't running on startup; I wonder if some work
> with
> mdadm and the LVM utilities would get you access to the volumes.
> It might
> at least be worth a try.

I find that LVM-over-RAID is not autodetected by most rescue disks.
It's necessary to first bring up the RAID array manually with mdadm,
then run vgscan and vgchange -ay to start up LVM. After that it
should work fine. I've done this before, but it's been a little
while and I can't remember the exact command lines I used.




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Em Qui, 2007-10-04 Ãs 15:32 -0700, David Brodbeck escreveu:
> On Oct 3, 2007, at 6:03 PM, Daniel Burrows wrote:
>
> > On Sat, Sep 29, 2007 at 07:37:10PM -0500, helices
> > <helices@helices.org> was heard to say:
> >> The problem with knoppix cd, and the debian installation/rescue
> >> cd, is
> >> that they do NOT understand the specifics of my lvm over software
> >> raid
> >> 5. The specifics required probably all reside under /etc -- on a
> >> filesystem in lvm on software raid 5.
> >
> > Are you sure this is the case? Software raid and LVM are both
> > kernel
> > things (with userland support utilities), and they're autodetected
> > using
> > magic numbers on the partitions. As long as the kernel is compiled
> > with
> > support, I'd expect them to be accessible. It might be that the
> > autodetection just isn't running on startup; I wonder if some work
> > with
> > mdadm and the LVM utilities would get you access to the volumes.
> > It might
> > at least be worth a try.
>
> I find that LVM-over-RAID is not autodetected by most rescue disks.
> It's necessary to first bring up the RAID array manually with mdadm,
> then run vgscan and vgchange -ay to start up LVM. After that it
> should work fine. I've done this before, but it's been a little
> while and I can't remember the exact command lines I used.
>
>
The problem is grub. Grub has no support for this (lvm over raid)

you need a lilo booter (wich the etch installer installs).
and a lilo based rescue CD.

I was bitten quite often by this problem, therefore I use a /boot
outside of raid/lvm, /boot on one HD, variouos swaps on the others.

after that you can boot with any Grub CD

Michel.




>
>

On Tue, Oct 09, 2007 at 04:04:52PM -0300, loos wrote:
>
> The problem is grub. Grub has no support for this (lvm over raid)
>
> you need a lilo booter (wich the etch installer installs).
> and a lilo based rescue CD.
>
> I was bitten quite often by this problem, therefore I use a /boot
> outside of raid/lvm, /boot on one HD, variouos swaps on the others.
>
> after that you can boot with any Grub CD
>

You can also create a raid1 big enough for /boot; put a mirror on all
the drives, install grub in the MBR of all the drives.

Doug.


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On Tue, Oct 09, 2007 at 04:04:52PM -0300, loos <loos@mloos.eti.br> was heard to say:
> Em Qui, 2007-10-04 às 15:32 -0700, David Brodbeck escreveu:
> > I find that LVM-over-RAID is not autodetected by most rescue disks.
> > It's necessary to first bring up the RAID array manually with mdadm,
> > then run vgscan and vgchange -ay to start up LVM. After that it
> > should work fine. I've done this before, but it's been a little
> > while and I can't remember the exact command lines I used.
> >
> >
> The problem is grub. Grub has no support for this (lvm over raid)

That's only true if you're trying to directly boot the system from the
CD. If you want to boot a live CD (Knoppix, etc) and access your
filesystem from it, then Grub doesn't enter into the picture.

Daniel


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