Re: [PATCH} Add RAID devices.

[myglc2 <myglc2@gmail.com>]

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Andreas Enge <andreas@enge.fr> writes:

> On Sat, Jul 30, 2016 at 07:05:25PM -0400, myglc2 wrote:
>> > I might write a more detailed blog post about this; there is a little
>> > subtlety with the non-automatic determination of dependencies between
>> > devices, so one needs to make sure that the partitions to be assembled
>> > are present before the mdadm command is executed.
>> I rebooted and the array is not assembled ;-(
>
> Strange! But I will also tell you the subtlety ;-)  Here is a trick to use
> (thanks to Ludovic):
> (define md0
>   (mapped-device
>     (source (list "/dev/sda2" "/dev/sdb2"))
>       (target "/dev/md0")
>       (type raid-device-mapping)))
> (operating-system
> ...
>   (mapped-devices (list md0))
>   (file-systems (cons (file-system
>                         (title 'device)
>                         (device "/dev/md0")
>                         (dependencies (list md0))
>                         (mount-point "/")
>                         (type "ext4"))
>                       %base-file-systems))
>
> The "dependencies" field makes sure that the file system is only mounted
> after the array is assembled; I am not sure that this is your problem,
> but you might want to give it a try.
>
> In the long run, this should be reprogrammed: Devices and file systems
> should wait until all their "inputs" are present, or at least wait for
> a reasonable time.

Thanks, I tried that. the 'guix system reconfigure' succeeds and starts
the raid array (please see system35.scm & system35.log, attached).

But the reboot hangs at:

[...] clocksource: Switched to clocksource tsc


[-- Attachment #2: system35.log --]
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root@g1 ~# cat /proc/mdstat
Personalities : [raid1] 
unused devices: <none>
root@g1 ~# rm -fr /mnt/md0
root@g1 ~# ls /mnt
root@g1 ~# guix system reconfigure system35.scm
substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
The following derivation will be built:
   /gnu/store/rd6m57pga9ddf9lsvfja6jybb1vnrj7d-grub.cfg.drv
/gnu/store/l1mpwaxlf2nhm18vzxir9npdi2inis7j-system
/gnu/store/s6x0j9cy0vgfnzc6xybrgcx0k327brrf-grub.cfg
/gnu/store/7p3pc22s5ap4smm6habggjcgj83aaidv-grub-2.02beta3
activating system...
setting up setuid programs in '/run/setuid-programs'...
populating /etc from /gnu/store/7v9p4s8hkx8k58vsz6zk1q58hws9dmbz-etc...
usermod: no changes
usermod: no changes
usermod: no changes
making '/gnu/store/l1mpwaxlf2nhm18vzxir9npdi2inis7j-system' the current system...
guix system: loading new services: device-mapping-/dev/md0 file-system-/mnt/md0...
shepherd: Evaluating user expression (register-services (primitive-load "/gn...") #).
shepherd: Service device-mapping-/dev/md0 has been started.
shepherd: Service file-system-/mnt/md0 has been started.
Installing for i386-pc platform.
Installation finished. No error reported.
root@g1 ~# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdc1[0] sdb1[1]
      239809536 blocks super 1.2 [2/2] [UU]
      bitmap: 1/2 pages [4KB], 65536KB chunk

unused devices: <none>
root@g1 ~# exit
exit

Process shell finished

[-- Attachment #3: system35.scm --]
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;;; g1 system config
(use-modules (gnu))
(use-service-modules networking ssh)
(use-package-modules
 base
 admin
 disk
 linux                 ; mdadm
 package-management    ; guix
 screen
 ghostscript           ; gs-fonts
 fonts                 ; font-dejavu font-gnu-freefont-ttf
 curl                  ; lpaste
 ssh
 xorg certs
 rsync
 wget
 version-control       ; git
 aspell
 emacs
 cups
 graphviz
 qemu
 )
(define md0
  (mapped-device
   (source (list "/dev/sdb1" "/dev/sdc1"))
   (target "/dev/md0")
   (type raid-device-mapping)))
(operating-system
  (host-name "g1")
  (timezone "America/New_York")
  (locale "en_US.utf8")
  (bootloader (grub-configuration (device "/dev/sda")))
  (mapped-devices (list md0))
  (initrd (lambda (fs . args)
	    (apply base-initrd fs
		   #:extra-modules '("raid1")
		   #:mapped-devices '((mapped-device
				       (source (list "/dev/sdb1" "/dev/sdc1"))
				       (target "/dev/md0")
				       (type raid-device-mapping)))				      
		   args)))
  (file-systems (cons*
		 (file-system
		   (device "ssd-root")
		   (title 'label)
		   (mount-point "/")
		   (type "ext4"))
		 (file-system
		   (title 'device)
		   (device "/dev/md0")
		   (dependencies (list md0))
		   (mount-point "/mnt/md0")
		   (create-mount-point? #t)
		   (type "ext4"))
		 %base-file-systems))
  (users (cons* (user-account
		 (name "glc")
		 (group "users")
		 (supplementary-groups '("wheel"))
		 (home-directory "/home/glc"))
		(user-account
		 (name "g1")
		 (group "users")
		 (supplementary-groups '("wheel" "kvm"))
		 (home-directory "/home/g1"))
		(user-account
		 (name "g1x")
		 (group "users")
		 (supplementary-groups '("wheel" "kvm"))
		 (home-directory "/home/g1x"))
		(user-account
		 (name "gx")
		 (group "users")
		 (supplementary-groups '("wheel" "kvm"))
		 (home-directory "/home/gx"))
		%base-user-accounts))
  (packages
   (cons*
    glibc-utf8-locales
    parted
    mdadm
    qemu
    guix
    screen
    openssh nss-certs xauth
    rsync wget
    curl                                                     ;lpaste
    git git-manpages
    gs-fonts font-dejavu font-gnu-freefont-ttf
    aspell
    emacs
    flycheck paredit magit
    emacs-zenburn-theme emacs-markdown-mode emacs-web-mode
    cups
    graphviz
    %base-packages))
  (services (cons* (dhcp-client-service)
		   (lsh-service #:port-number 22)
		   %base-services)))