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Old 11-18-2011, 05:39 PM
"Mark W. Jeanmougin"
 
Default RAID0 and Fedora 16 / f16

Hey guys,

Long time user, first time caller. I've been using Fedora since it was
RH4. Many box sets later, I find myself with an issue I can't solve.
Even Google isn't helping me out much.

In previous (pre-F14) versions, I partition (msdos, not GPT) my
systems something like this:

# fdisk -l /dev/sda
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x9e218bdf

Device Boot Start End Blocks Id System
/dev/sda1 * 63 530144 265041 fd Linux raid autodetect
/dev/sda2 530145 84437639 41953747+ fd Linux raid autodetect
/dev/sda4 84437640 3907024064 1911293212+ 5 Extended
/dev/sda5 84437703 3907024064 1911293181 fd Linux raid autodetect

sdb is setup identically. The idea is that sd[ab]1 is a RAID1
containing /boot. sd[ab]2 is another RAID1 containing an LVM VG which
contains the rest of the OS. Most of the time, the rest of the space
on the system is a final RAID1 for data. Sometimes, I'll have a RAID0
if performance is more important than uptime.

Here's the mdadm config:

# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4]

md2 : active raid1 sda5[0] sdb5[1]
1911292021 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sda2[0] sdb2[1]
41952651 blocks super 1.2 [2/2] [UU]

md0 : active raid1 sda1[0] sdb1[1]
264960 blocks [2/2] [UU]

unused devices: <none>

Then, here's what the (non-data) filesystems look like:

[root@blu images]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_blu0-lv_root
786M 635M 112M 86% /
tmpfs 5.9G 2.2M 5.9G 1% /dev/shm
/dev/mapper/vg_blu0-lv_tmp
1.5G 40M 1.5G 3% /tmp
/dev/mapper/vg_blu0-lv_var
1.5G 765M 638M 55% /var
/dev/mapper/vg_blu0-lv_usr
14G 11G 3.0G 78% /usr
/dev/md0 251M 144M 82M 64% /boot
/dev/mapper/vg_blu0-lv_home
5.0G 4.1G 656M 87% /home

So, under Fedora 16, I'm trying to duplicate this. I saw in the docs
that /usr shouldn't be split from /. OK. So, increase the size of
lv_root, and get rid of lv_usr. No big deal.

For my install, I setup (GPT, by default) partition tables with a
simplified version of above:

/dev/mapper/vg00-lv_root 2.0G on /
/dev/md0 on /boot

That's it.

sda1 is a 1049kB partition for "bios_grub". md0 is a raid1 of sda3
sdb2. md1 is sdb1 & sda2. Then, md1 holds the vg00. This is about as
simple as I can make it.

During the install, I select: Install boot loader on /dev/sda. Minimal
Install. Then I get a Warning "There was an error installing the
bootloader. The system may not be bootable". Looking at the other
virtual consoles shows me:

Alt-F3:
INFO storage: bootloader stage1 target device is sda
INFO storage: bootloader stage2 target device is md0
[Ed: Which is odd since I chose sda for the installation target in the
earlier step]

Alt-F5:
/sbin/grub2-setup: warn: This GPT partition label has no BIOS Boot
Partition; embedding won't be possible!.
/sbin/grub2-setup: error: embedding is not possible, but this is
required when the root device is on a RAID array or LVM volume.
Generating grub.cfg ...
Found linux image: /boot/vmlinux-3.1.0-7.fc16_x86_64
Found initrd image: /boot/initramfs-3.1.0-7.fc16_x86_64
done
Installation finished. No error reported.
/sbin/grub2-setup: warn: This GPT partition label has no BIOS Boot
Partition; embedding won't be possible!.
/sbin/grub2-setup: error: embedding is not possible, but this is
required when the root device is on a RAID array or LVM volume.

I know to let the RAID's finish building before I reboot, so that's not it.

After the reboot I get:
GRUB loading.
Welcome to GRUB!

error: no such device: 71ec265a-f934-40a6-b02d-3ff3a274d229.
Entering rescue mode...
grub rescue>

ls just shows "(hd0)". It doesn't show any partitions.

set shows:
prefix=(hd0)/grub2
root=hd0

"insmod normal" says "error: unknown filesystem."

I've tried "set prefix=(hd0,0)/grub2", then "insmod normal". That
gives "error: no such partition". I've tried passing 0, 1, and 2 as
values for the partition. They all give the same value.

I'm really not sure where to go from here. I can't believe I'm the
first person to do mdadm RAID1 under F16.

If I do a "default" partitioning installation, then everything works
fine, but I don't get RAID1. Or, any RAID at all. Just an LV spanning
my drives.

Finally, this behavior is consistent on physical hardware and in a VM under KVM.

How do I install onto RAID 1?

Thanks in advance,

MJ
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Old 11-18-2011, 07:36 PM
Roberto Ragusa
 
Default RAID0 and Fedora 16 / f16

On 11/18/2011 07:39 PM, Mark W. Jeanmougin wrote:
> sda1 is a 1049kB partition for "bios_grub". md0 is a raid1 of sda3
> sdb2. md1 is sdb1 & sda2. Then, md1 holds the vg00. This is about as
> simple as I can make it.

Just my two cents.
Wouldn't have been wiser to partition the two disks with the same layout?
That is, create a 1049kB sdb1 (even if unused) and keep sda2+sdb2 and sda3+sdb3.
It would be more confusing for the administrator, and it would make easier
to exchange the roles of the disks in the future.
I would also suggestion to call sda+sdb3 as md3 as so on. There is no rule
that you must have md0, then md1, then md2; having just md2 and md3 would be
simpler.

Apart from this "good practice" considerations, I don't think to have
great suggestions for you about the grub2 problems.

> During the install, I select: Install boot loader on /dev/sda. Minimal
> Install. Then I get a Warning "There was an error installing the
> bootloader. The system may not be bootable". Looking at the other
> virtual consoles shows me:
>
> Alt-F3:
> INFO storage: bootloader stage1 target device is sda
> INFO storage: bootloader stage2 target device is md0
> [Ed: Which is odd since I chose sda for the installation target in the
> earlier step]
>
> Alt-F5:
> /sbin/grub2-setup: warn: This GPT partition label has no BIOS Boot
> Partition; embedding won't be possible!.

Is the GPT sda1 correctly marked for boot?

--
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Old 11-18-2011, 08:47 PM
"Mark W. Jeanmougin"
 
Default RAID0 and Fedora 16 / f16

On Fri, Nov 18, 2011 at 15:36, Roberto Ragusa <mail@robertoragusa.it> wrote:
> On 11/18/2011 07:39 PM, Mark W. Jeanmougin wrote:
>> sda1 is a 1049kB partition for "bios_grub". md0 is a raid1 of sda3
>> sdb2. md1 is sdb1 & sda2. Then, md1 holds the vg00. This is about as
>> simple as I can make it.
>
> Just my two cents.
> Wouldn't have been wiser to partition the two disks with the same layout?
> That is, create a 1049kB sdb1 (even if unused) and keep sda2+sdb2 and sda3+sdb3.
> It would be more confusing for the administrator, and it would make easier
> to exchange the roles of the disks in the future.
> I would also suggestion to call sda+sdb3 as md3 as so on. There is no rule
> that you must have md0, then md1, then md2; having just md2 and md3 would be
> simpler.

That's my preference as well. I "kept it simple" for the purposes of
filing this bug report list posting.

>> During the install, I select: Install boot loader on /dev/sda. Minimal
>> Install. Then I get a Warning "There was an error installing the
>> bootloader. The system may not be bootable". Looking at the other
>> virtual consoles shows me:
>>
>> Alt-F3:
>> INFO storage: bootloader stage1 target device is sda
>> INFO storage: bootloader stage2 target device is md0
>> [Ed: Which is odd since I chose sda for the installation target in the
>> earlier step]
>>
>> Alt-F5:
>> /sbin/grub2-setup: warn: This GPT partition label has no BIOS Boot
>> Partition; embedding won't be possible!.
>
> Is the GPT sda1 correctly marked for boot?

Here's what "parted /dev/sda print" has to say:
Number Start End Size File system Name Flags
1 1049kB 2097kB 1049kB [NULL] [NULL] bios_grub
2 2097kB 5245MB 5243MB [NULL] [NULL] raid
3 10.5GB 11.0GB 524MB ext4 "software RAID" boot

So, it looks like sda3 is set to boot. So, I changed it so that sda1
has the boot flag. That also cleared the "bios_grub" flag on sda1.
Then, I removed the boot flag from sda3. It's still doing the same
thing:
error: no such device: 71ec265a-f934-40a6-b02d-3ff3a274d229

Ideas?

MJ
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Old 11-18-2011, 11:30 PM
Sam Varshavchik
 
Default RAID0 and Fedora 16 / f16

Mark W. Jeanmougin writes:


# fdisk -l /dev/sda
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x9e218bdf

Device Boot Start End Blocks Id System
/dev/sda1 * 63 530144 265041 fd Linux raid autodetect


You need to move up the start of partition up to 2048, from 63. Grub won't
fit here, as you've discovered.



After the reboot I get:
GRUB loading.
Welcome to GRUB!

error: no such device: 71ec265a-f934-40a6-b02d-3ff3a274d229.


http://fedoraproject.org/wiki/Common_F16_bugs#Cannot_boot_with_.2Fboot_partition _on_a_software_RAID_array

You need to:

1) Move partition 1 to start on logical sector 2048.

2) Use the workaround given there.

Both 1 and 2 are required to fix this. Neither one, by itself, will give you
something that boots.


If you're doing a fresh install, this shouldn't be too bad. If you're trying
to salvage a botched upgrade, you have to move up your sd[ab]1, before you
can do anything. It can be done in rescue mode, but won't be easy. Given the
size of the /boot partition, the easiest thing to do would probably be to
temporarily copy /boto to one of your bigger partitions, resize it, and
restore it.


Sounds easier than it actually is. fdisk won't be able to write out an
updated partition table if something still has the disk mounted. So, you'll
have to back up /boot, stop all disk arrays, use fdisk to gingerly remove
partition 1 from both disks, and add it back it, slightly smaller, assemble
a new mdraid array, being sure to specify version 1.0 raid superblock. mdadm
will likely whine that it's still seeing its old superblock, with the wrong
partition size. Just follow mdadm's instructions to zero it out. Reformat
the slightly smaller sd[ab]1 as ext[34], start up all the arrays, mount
everything back up, and restore your former /boot (and update the fstab on
your root partition, to reflect the new /boot uuid).


Then you should be able to go into chroot /mnt/sysimage, and fix grub as
instructed on the known issues page. Been there myself, have the wounds to
prove it…



If I do a "default" partitioning installation, then everything works
fine, but I don't get RAID1. Or, any RAID at all. Just an LV spanning
my drives.


… and you should get rid of LVM as well. It offers very few benefits for a
generic RAID1 setup, like you have. Just use native primary/extended
partitions, and mount them directly.


P.S. Your 256mb for /boot is a bit small-ish, these days, too.

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