problem installing on RAID partition and hot to rescue

problem installing on RAID partition and hot to rescue

[Giovanni Biscuolo]

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Hello Guix!

yesterday I installed Guix 1.0.0 on bare metal (HP ProLiant DL380 G8)
using the Graphical Installation

I "manually" created a RAID 1 device /dev/md0 and used that device with
the "guided partitioning" method: Guix was installed on /mnt (up until
"populating '/mnt'....) but grub-install failed with this error:

  error: diskfilter writes are not supported

the command used by the installer was this:

  /gnu/store/6b2f9iz8...-grub-2-02/sbin/grub-install --no-floppy --target=i386-pc --boot-directory /mnt/boot /dev/md0

(I copied the above command from a picture of the console, no log sorry)

since I used a "workaround" and creating a RAID device is (still) not
supported by the Graphical Install guided/manual procedure (am I
wrong?), I guess I have to "manually" fix the grub-install step

AFAIU grub-install does not support using /dev/md? devices but I have to
install grub using the underlying physical devices (/dev/sda and /dev/sdb
in this case): correct?

after the failure I tried to remount /dev/md0 as /mnt to try to
grub-install again (on /dev/sda and /dev/sdb) *but* /dev/md0 was busy by
some process and I could not mount it again... I was in a hurry and I
had to stop there, but I suppose this kind of "block" (sorry I had no
time to investigate what process was still using /dev/md0) should be
addressed

late this week I'll be able to work on this again, I plan to start Guix
from the USB install media and use it as a rescue disk to complete
the grub-install on the physical devices: I've done this kind of fixes
several times with several rescue-distros, I should have no problem
using Guix this time

as a side note: what about raplacing mdraid with brtfs?  I have not much
experience with btrfs (especially as a boot filesystem) so I tend to be
conservative and use what I know (and is maybe more mature?)

...anyway: is btrfs formatting using raid1 (or raid10) mode supported
using the Guix Graphical Installer?

last but not least: should we add a guided RAID<N> partitioning
method to the Graphical Installer?

thank you Guix!

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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Re: problem installing on RAID partition and hot to rescue

[Ludovic Courtès]

Hello!

Giovanni Biscuolo <g@xelera.eu> skribis:

> I "manually" created a RAID 1 device /dev/md0 and used that device with
> the "guided partitioning" method:

What did you do exactly?  Did you modify /mnt/etc/config.scm once the
graphical installer had displayed it?  And did you also re-partition and
re-mount your disks accordingly?

That sounds inconvenient and error-prone.  :-/

> last but not least: should we add a guided RAID<N> partitioning
> method to the Graphical Installer?

I guess we should!

Ludo’.

Re: problem installing on RAID partition and hot to rescue

[Giovanni Biscuolo]

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Hello!

Ludovic Courtès <ludo@gnu.org> writes:

> Giovanni Biscuolo <g@xelera.eu> skribis:
>
>> I "manually" created a RAID 1 device /dev/md0 and used that device with
>> the "guided partitioning" method:
>
> What did you do exactly?

right before the partitioning phase in the installer, I switched to a
terminal console, partitioned the two physical disks [1] with cfdisk
with 1 partition each (/dev/sda1 and /dev/sdb1) then assembled the RAID
1 device via mdadm, something like

   mdadm --create --verbose /dev/md0 --level=mirror --raid-devices=2 /dev/sda1 /dev/sdb1

then switched back to the installer and used /dev/md0 as the device for
"Guided partitioning": it worked well up until grub-install

> Did you modify /mnt/etc/config.scm once the graphical installer had
> displayed it?

ehrm... no :-S
I should have done this, as documented in the manual [2]

> And did you also re-partition and re-mount your disks accordingly?

no but I don't understand what's the rationale to re-partition (delete
and recreate partitions?) and re-mount the partitions ad this phase of
installation

> That sounds inconvenient and error-prone.  :-/

do you mean: it's inconvenient to manually edit /mnt/etc/config.scm once
the graphical installer displayed it and before the "guix system init
/mnt/etc/config.scm /mnt" by the installer?

thinking twice I realize that mix-and-match guided (installer) and
manual installation is not a great idea... it was a dirty hack :-)

by the way, I'll try to rescue the system from the unbootable state:
I'll re-assemble /dev/md0, chroot to it and try to grub-install and
re-init Guix system with a fixed config.scm

if the above fails, I'll re-install from scratch using the manual
installation method

>> last but not least: should we add a guided RAID<N> partitioning
>> method to the Graphical Installer?
>
> I guess we should!

I'd like to help with patches but I'm still not able to code in Guile
[3]... I can test it 10 times if that feature will be added :-)

Thanks! Gio'


[1] actually they are RAID 0 logical volumes created via the "smart
array" HP controller software: I was not able (it seems impossible) to
configure the controller for direct access of *physical* disks from the
OS (HP Smart Array P410 - I **hate** this)... but that's a completely
different story... or not?
https://serverfault.com/questions/29349/disabling-raid-feature-on-hp-smart-array-p400#41975

[2]
https://www.gnu.org/software/guix/manual/en/html_node/Mapped-Devices.html#Mapped-Devices

[3] configuring and packaging is easy but it's not the kind of coding we need


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-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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Re: problem installing on RAID partition and hot to rescue

[Ludovic Courtès]

Hi Giovanni,

Giovanni Biscuolo <g@xelera.eu> skribis:

> do you mean: it's inconvenient to manually edit /mnt/etc/config.scm once
> the graphical installer displayed it and before the "guix system init
> /mnt/etc/config.scm /mnt" by the installer?
>
> thinking twice I realize that mix-and-match guided (installer) and
> manual installation is not a great idea... it was a dirty hack :-)
>
> by the way, I'll try to rescue the system from the unbootable state:
> I'll re-assemble /dev/md0, chroot to it and try to grub-install and
> re-init Guix system with a fixed config.scm
>
> if the above fails, I'll re-install from scratch using the manual
> installation method

Yeah, what I mean is that, for now, you should use the manual
installation method entirely.  The guided method assumes it has control
over the whole process, so if you do things behind its back, it’s likely
to go awry.

It wouldn’t be That Hard™ to adjust the installer to so that it offers
RAID as an additional option, but right now the focus is on shipping
1.0.1 to address the more pressing issues.

Thanks,
Ludo’.