Damon L. Chesser wrote:
> Ivan Glushkov wrote:
>> Damon L. Chesser wrote:
>>
>>> snip
>>>
>>>> I taught I have to install the grub on the raid array, thus the grub
>>>> will put a copy of itself on the first partition on both hard drives,
>>>> used for the raid1, right?
>>>>
>>> Wrong AFAIK. You can do that IF you have a boot loader on the MBR
>>> pointing to grub.
>>>
>>
>> Now I am confused. Isn't grub a boot loader? Why would I need another
>> boot loader pointing to grub? I want to put grub on the MBR of both hard
>> drives from which my raid1 array consist of.
>>
>> BIOS does not read software raid and knows nothing
>>
>>> about software raid.
>>>
>>
>> Indeed, but I do not expect from the bios to read my raid array. I
>> merely want it to look for boot record in the MBR of one of the two hard
>> drives on which I have my raid arrays.
>>
>> Software raid does not come into play until the
>>
>>> kernel via initrd is loaded. Install to the MBR of the first HD of the
>>> array, then use grub to install into the MBR of the other members.
>>>
>>
>> What I meant with the paragraph you are referring to is exactly that:
>> issuing:
>>
>> grub-install /dev/md0
>>
>> should install (as fas as I understand it) a copy of grub in each hdd
>> from which the raid1 consist of (note: the partitions from both hard
>> drives included in md0 are both 512 MB and starting from the beginning
>> of the hard drives).
>>
>
> Truly, I don't know if you install grub onto a raid1 if it will install
> it onto the MBR of both physical HDs. I just always made partitions for
> the /boot, installed to one, moved the data around and made a mdX out of
> it and installed grub onto the other member. Re-inventing the wheel?
> Probably.
>> If I
>>
>>> am wrong, then it is news to me, but hey, I will learn new things! See
>>> my old "howto" on Linux, grub and raid at damtek.com for the exact
>>> commands. It is not pretty, but it will work.
>>>
>>
>> I tried that. Thanks.
>>
>> Basically the problem was easily solved. I had to tag both partitions to
>> be used for my /boot raid1 array as primary and bootable (stupid of me,
>> I know). But there is now another problem:
>>
>> I see already the grub initial screen, but when I hit enter, I get the
>> following:
>>
>> Booting 'Debian GNU/Linux, kernel 2.6.24-1-amd64'
>>
>> root (hd5,0)
>> Filesystem type unknown, partition type 0x7
>> kernel //vmlinuz-2.6.24-1-amd64 root=/dev/mapper/vg00-root ro linux26
>> quiet
>>
>> Error 17: Cannot mount selected partition
>>
>> Press any key to continue...
>>
>> I suppose grub does not know anything about LVM and the partitions on
>> that. If I am right, I have to rebuild initrd, right? But how do I tell
>> it to enable the lvm?
>>
>
> You have me there, it should have done it automagicaly when it
> installed. Use rescue mode, but I am not sure what command you should
> use to re-generate it. Perhaps chroot to your /, then try to run mkinitrd.
>
> do you have a line in grub like this?
>
> title Debian GNU/Linux, kernel 2.6.25-1-amd64
> root (hd0,5)
> kernel /boot/vmlinuz-2.6.25-1-amd64 root=/dev/hda6 ro quiet
> ------->>>>>>> initrd /boot/initrd.img-2.6.25-1-amd64
> <<<<<<<<<<<-------

I have this line in /boot/grub/menu.lst

I tried in the following sequence to:

0. boot resque
1. mount /boot from raid1 and the other directories from the lvm volumes

1. enter lvm into /etc/modules,
2. rebuild initrd with:

mkinitramfs -o /boot/grub/initrd.img-2.6.24-1-amd64

3. install grub into the MBR of both disk with

grub-install /dev/sdc
grub-install /dev/sdd

but still the same message appears when I try to boot

How can I check if the lvm support is really seen by grub?
I find this (http://grub.enbug.org/LVMandRAID) article claiming that I
have to enter "insmod lvm" in a file named grub.cfg. But I don't have a
file like this in my system?!

>
> If not, that would seem to mean you don't have an intrd.
>
>



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On Wed, May 07, 2008 at 09:29:14PM +0200, NN_il_Confusionario wrote:
> On Wed, May 07, 2008 at 02:48:57PM -0400, Damon L. Chesser wrote:
> > Truly, I don't know if you install grub onto a raid1 if it will install
> > it onto the MBR of both physical HDs.
>
> I have not done this recently, but I am sure that some yeras ago it was
> not so. I had to install separately grub on the MBR of both disks (say,
> sda and sdb, or hd0 and hd1 in grub language). And since then I have not
> changed method. Moreover with

Presumably if one drive fails then you can still boot off the other one?
Or am I off base?

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Chris Bannister wrote:
> On Wed, May 07, 2008 at 09:29:14PM +0200, NN_il_Confusionario wrote:
>
>> On Wed, May 07, 2008 at 02:48:57PM -0400, Damon L. Chesser wrote:
>>
>>> Truly, I don't know if you install grub onto a raid1 if it will install
>>> it onto the MBR of both physical HDs.
>>>
>> I have not done this recently, but I am sure that some yeras ago it was
>> not so. I had to install separately grub on the MBR of both disks (say,
>> sda and sdb, or hd0 and hd1 in grub language). And since then I have not
>> changed method. Moreover with
>>
>
> Presumably if one drive fails then you can still boot off the other one?
> Or am I off base?
>
>
Yes.

Ivan,

I am installing a vm to mirror what you have done to test it out. I
don't have the answer.

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SNIP
>
> I have this line in /boot/grub/menu.lst
>
> I tried in the following sequence to:
>
> 0. boot resque
> 1. mount /boot from raid1 and the other directories from the lvm volumes
>
> 1. enter lvm into /etc/modules,
> 2. rebuild initrd with:
>
> mkinitramfs -o /boot/grub/initrd.img-2.6.24-1-amd64
>
> 3. install grub into the MBR of both disk with
>
> grub-install /dev/sdc
> grub-install /dev/sdd
>
> but still the same message appears when I try to boot
>
> How can I check if the lvm support is really seen by grub?
> I find this (http://grub.enbug.org/LVMandRAID) article claiming that I
> have to enter "insmod lvm" in a file named grub.cfg. But I don't have a
> file like this in my system?!
>
>
>
>
Ivan,

As for LVM support for grub: the MBR has files pointing to your "root"
which in this term means place where the grub files are which is NOT in
an LVM. In your case this should be /dev/md0 or however GRUB reads that
(I confess, I don't know). I just installed, in a vm, debian using this
image:
http://ftp.nl.debian.org/debian/dist...tboot/mini.iso
which should be current snapshot of testing, net install mini.iso. I
did that to make sure we had the same OS.

I partitioned two 8G drives thusly: 1 120MB primary, 1 6.5GB extended.
I made the 1st partition into a raid1 (md0) and made the 2nd into a
raid1 (md1)

I put an a swap file on each drive (1.5G each, why run raid on a swap?
double your swap file space and you can ping between the two if you need
them)

I put LVM (System) on top of md1 and divided that into two logical
volumes (root 4.5G and home 2G or so)

I then was asked to install Grub into MBR of (hd0,0) which I agreed to.

rebooted. works just fine.

Cut your losses, if you have a network install, just do it again (unless
you are metered) and this time install grub on the physical HD. Then
use the grub command to mirror it to the raid1 member.

HTH.

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Ivan Glushkov wrote:
> Damon L. Chesser wrote:
>
>> SNIP
>>
>>> I have this line in /boot/grub/menu.lst
>>>
>>> I tried in the following sequence to:
>>>
>>> 0. boot resque
>>> 1. mount /boot from raid1 and the other directories from the lvm volumes
>>>
>>> 1. enter lvm into /etc/modules,
>>> 2. rebuild initrd with:
>>>
>>> mkinitramfs -o /boot/grub/initrd.img-2.6.24-1-amd64
>>>
>>> 3. install grub into the MBR of both disk with
>>>
>>> grub-install /dev/sdc
>>> grub-install /dev/sdd
>>>
>>> but still the same message appears when I try to boot
>>>
>>> How can I check if the lvm support is really seen by grub?
>>> I find this (http://grub.enbug.org/LVMandRAID) article claiming that I
>>> have to enter "insmod lvm" in a file named grub.cfg. But I don't have a
>>> file like this in my system?!
>>>
>>>
>>>
>>>
>> Ivan,
>>
>> As for LVM support for grub: the MBR has files pointing to your "root"
>> which in this term means place where the grub files are which is NOT in
>> an LVM. In your case this should be /dev/md0 or however GRUB reads that
>> (I confess, I don't know). I just installed, in a vm, debian using this
>> image:
>> http://ftp.nl.debian.org/debian/dist...tboot/mini.iso
>> which should be current snapshot of testing, net install mini.iso. I
>> did that to make sure we had the same OS.
>>
>> I partitioned two 8G drives thusly: 1 120MB primary, 1 6.5GB extended.
>> I made the 1st partition into a raid1 (md0) and made the 2nd into a
>> raid1 (md1)
>>
>
> Just two short questions here:
> 1. Did you format the md0 raid, and if yes, did you mount it?
> 2. Where is your /boot? On the root logical volume?
>
> Thanks in advance
>
Yes, ext3. /boot is on /dev/md0. /boot is NOT on the LVM, it is on
it's own raid1. /boot will NOT work from an LVM.
>
>> I put an a swap file on each drive (1.5G each, why run raid on a swap?
>> double your swap file space and you can ping between the two if you need
>> them)
>>
>> I put LVM (System) on top of md1 and divided that into two logical
>> volumes (root 4.5G and home 2G or so)
>>
>> I then was asked to install Grub into MBR of (hd0,0) which I agreed to.
>>
>> rebooted. works just fine.
>>
>> Cut your losses, if you have a network install, just do it again (unless
>> you are metered) and this time install grub on the physical HD. Then
>> use the grub command to mirror it to the raid1 member.
>>
>> HTH.
>>
>>
>
>
>
>
>

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Celejar wrote:
> On Tue, 06 May 2008 16:01:46 -0400
> "Damon L. Chesser" <damon@damtek.com> wrote:
>
> [snip]
>
>
>> you can not put grub (/boot) on an LVM. You can put /boot on a raid1.
>>
>
> Grub (/boot) can apparently be on LVM these days; from the GrubWiki
> (http://grub.enbug.org/LVMandRAID):
>
> <Quote>
>
> Installing GRUB while /boot is on RAID and/or LVM should be
> straightforward. Grub-setup will detect that and specify the GRUB root
> device/prefix accordingly, so GRUB will be able to find the files
> in /boot. If you have a RAID array you can specify the RAID device as
> destination device. Grub-setup will look at the members of the RAID
> array and install on the MBR of each disk.
>
> </Quote>
>
>
>> Damon L. Chesser
>>
>
> Celejar
> --
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>
>
>
Now you have gone off and made me learn something new, dangnabit! I
stand corrected. Thanks.

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On Wed, May 07, 2008 at 07:32:13PM +0200, Ivan Glushkov wrote:
> Damon L. Chesser wrote:
> > Ivan Glushkov wrote:
> >> Hi,
> >>
> >> I installed Debian on top of LVM and software RAID1 following this:
> >>
> >> http://dev.jerryweb.org/raid/
> >>
> >>
> >> Everything is fine except that I cannot boot the Debian afterwards
> >> ("Insert boot disk" message from the bios). I used /dev/sdc and
> >> /dev/sdd. First problem is that I do not know which hdd I should enter
> >> as the first boot device in the bios. Moreover, obviously the bios does
> >> not see the /dev/md0 array, since I guess first the raid array should be
> >> started in order for grub to be loaded. I explicitly issued grub-install
> >> /dev/md0 using the recovery mode of the debian installer, but that did
> >> not help.
> >>
>
> > you can not put grub (/boot) on an LVM. You can put /boot on a raid1.
> > If you made one raid1 device and made one partition on md0 you will not
> > be able to boot (assuming you then put LVM on top of that one
> > partition/used all of md0).
>
> No, that's not the problem. I followed exactly the mentioned article.
> There, two disks are used and partitioned in two partitions - the first
> ones are used for one RAID1, which is formatted as ext3 and used for the
> /boot directory (i.e. no lvm for /boot). The second partitions on both
> disks are arranged in a second RAID1 array on which I have created
> separate logical volumes for / /usr /var and so on.
>
> >
> > Redo what you did only make either two partitions to md0, one for boot
> > (110Mb is large enough for most) and on partition2 put the rest of your
> > system ontop of the LVM. Or, partition your two hds to have two mdadm
> > raid1 . One small md0 for /boot and one md1 for the system with LVM on it.
> >
> > You will then have to install grub on to hdd or if hdc fails, you will
> > not be able to boot as grub will be installed onto hdc MBR. Makes sense?
>
> I taught I have to install the grub on the raid array, thus the grub
> will put a copy of itself on the first partition on both hard drives,
> used for the raid1, right?

A raid1 array is special. Each component looks like a non-raid disk
except for the raid controll sectors at the _end_ of the partition.
Therefore, your /boot is on raid1 maid up (I think) of /dev/hdc and
/dev/hdd. Can the bios boot of those drives anyway or does it need hda
or hdb? So the bios doesn't have to know about the md0. It just reads
the drive as it it wasn't raid.

The bios finds grub. Grub goes looking for the kernel in /boot. Grub
also can't use raid, but also it can read one disk of a raid1 set. It
finds the kernel and loads it.

In the process of installing, the installer would have built the
initrd.gz with the raid support built-in. The kernel goes looking for a
root directory and uses the mapper section to sort out the LVM, which is
why the kernel command line includes /dev/mapper-something for the root.

The issue seems to be getting grub to load. I haven't read the howto
reference you gave, since I don't have the bandwidth or the time. What
was wrong with the instructions in the installation manual? If you
follow them and still have a problem, you can get support directly from
the people who wrote the installer on the debian-boot mailing list.

Doug.



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On Tue, 06 May 2008 16:01:46 -0400
"Damon L. Chesser" <damon@damtek.com> wrote:

[snip]

> you can not put grub (/boot) on an LVM. You can put /boot on a raid1.

Grub (/boot) can apparently be on LVM these days; from the GrubWiki
(http://grub.enbug.org/LVMandRAID):

<Quote>

Installing GRUB while /boot is on RAID and/or LVM should be
straightforward. Grub-setup will detect that and specify the GRUB root
device/prefix accordingly, so GRUB will be able to find the files
in /boot. If you have a RAID array you can specify the RAID device as
destination device. Grub-setup will look at the members of the RAID
array and install on the MBR of each disk.

</Quote>

> Damon L. Chesser

Celejar
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Ivan Glushkov wrote:
> Damon L. Chesser wrote:
>
>> SNIP
>>
>>> I have this line in /boot/grub/menu.lst
>>>
>>> I tried in the following sequence to:
>>>
>>> 0. boot resque
>>> 1. mount /boot from raid1 and the other directories from the lvm volumes
>>>
>>> 1. enter lvm into /etc/modules,
>>> 2. rebuild initrd with:
>>>
>>> mkinitramfs -o /boot/grub/initrd.img-2.6.24-1-amd64
>>>
>>> 3. install grub into the MBR of both disk with
>>>
>>> grub-install /dev/sdc
>>> grub-install /dev/sdd
>>>
>>> but still the same message appears when I try to boot
>>>
>>> How can I check if the lvm support is really seen by grub?
>>> I find this (http://grub.enbug.org/LVMandRAID) article claiming that I
>>> have to enter "insmod lvm" in a file named grub.cfg. But I don't have a
>>> file like this in my system?!
>>>
>>>
>>>
>>>
>> Ivan,
>>
>> As for LVM support for grub: the MBR has files pointing to your "root"
>> which in this term means place where the grub files are which is NOT in
>> an LVM. In your case this should be /dev/md0 or however GRUB reads that
>> (I confess, I don't know). I just installed, in a vm, debian using this
>> image:
>> http://ftp.nl.debian.org/debian/dist...tboot/mini.iso
>> which should be current snapshot of testing, net install mini.iso. I
>> did that to make sure we had the same OS.
>>
>> I partitioned two 8G drives thusly: 1 120MB primary, 1 6.5GB extended.
>> I made the 1st partition into a raid1 (md0) and made the 2nd into a
>> raid1 (md1)
>>
>
> Just two short questions here:
> 1. Did you format the md0 raid, and if yes, did you mount it?
> 2. Where is your /boot? On the root logical volume?
>
> Thanks in advance
>
>
>> I put an a swap file on each drive (1.5G each, why run raid on a swap?
>> double your swap file space and you can ping between the two if you need
>> them)
>>
>> I put LVM (System) on top of md1 and divided that into two logical
>> volumes (root 4.5G and home 2G or so)
>>
>> I then was asked to install Grub into MBR of (hd0,0) which I agreed to.
>>
>> rebooted. works just fine.
>>
>> Cut your losses, if you have a network install, just do it again (unless
>> you are metered) and this time install grub on the physical HD. Then
>> use the grub command to mirror it to the raid1 member.
>>
>> HTH.
>>
>>
>
>
In light of the LVM and RAID article, I guess you can put grub on a LVM
or a mddevice. However, grub during the install portion of debian,
testing did not do that, it defaulted to hd0,0 and I took it. Is that
the difference between my working install and your non-booting install?

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On Wed, May 07, 2008 at 07:32:13PM +0200, Ivan Glushkov wrote:
> Damon L. Chesser wrote:
> > Ivan Glushkov wrote:
> >> Hi,
> >>
> >> I installed Debian on top of LVM and software RAID1 following this:
> >>
> >> http://dev.jerryweb.org/raid/
> >>
> >>
> >> Everything is fine except that I cannot boot the Debian afterwards
> >> ("Insert boot disk" message from the bios). I used /dev/sdc and
> >> /dev/sdd. First problem is that I do not know which hdd I should enter
> >> as the first boot device in the bios. Moreover, obviously the bios does
> >> not see the /dev/md0 array, since I guess first the raid array should be
> >> started in order for grub to be loaded. I explicitly issued grub-install
> >> /dev/md0 using the recovery mode of the debian installer, but that did
> >> not help.
> >>
> >> Thanks in advance,
> >> Ivan

Hi

I don't think this is a lvm / grub / raid1 issue.

you have stated that the 2 disk being used are sdc + sdd, by this i
presume there are 2 other disks in the box ? Have you ever written a
mbr to sda ? This is the first device the (usualy) the bios will try
and boot and the message sounds like your bios going, hey there is
nothing on this first disk for me to work with please insert disk.

Q) do you have 2 other disks in the machine
q) can you write a mbr to sda
q) or can you set your bios to boot from sdc

alex

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