Re: booting from a raid1

[Tom H]

On Sun, Oct 3, 2010 at 9:34 AM, lee <address@hidden> wrote:
> On Sun, Oct 03, 2010 at 07:34:15AM -0400, Tom H wrote:
>> On Fri, Oct 1, 2010 at 10:30 AM, lee <address@hidden> wrote:
>>> On Fri, Oct 01, 2010 at 03:49:28PM +0200, lee wrote:
>>>> On Fri, Oct 01, 2010 at 09:25:19AM -0400, Tom H wrote:
>>>>> On Fri, Oct 1, 2010 at 8:50 AM, lee <address@hidden> wrote:
>>>>>> On Fri, Oct 01, 2010 at 12:22:28PM +0200, Emil Micek wrote:
>>>>>>> On Fri, 1 Oct 2010, lee wrote:
>>>
>>>>>>> As far as i know grub2 can't boot from raid arrays with version 1.2
>>>>>>> metadata superblock. At least your /boot partition must reside on
>>>>>>> RAID with version 0.9 superblock.
>>>>>>
>>>>>  grub2  (1.98+20100720-1) unstable; urgency=low
>>>>
>>>> There seems to be version 1.98+20100 in testing, so it should work:
>>>>
>>>> yun:~# apt-cache show grub2
>>>> Version: 1.98+20100804-4
>>>>
>>>> need to/can I somehow use chroot to switch to the new root partition
>>>> and then use grub-install or grub-mkconfig from there so that it will
>>>> create the grub.cfg as needed?
>>>
>>> Ok, I tried with chroot, but grub-install doesn't create a grub.cfg at
>>> all. It only warns about improperly nested partitions and an unknown
>>> filesystem as before but says the installation finished with no
>>> errors.
>>>
>>> When running grub-mkconfig, I'm getting the following output (letting
>>> aside the warnings and the error message about the unknown filesystem):
>>>
>>> ### BEGIN /etc/grub.d/00_header ###
>>> if [ -s $prefix/grubenv ]; then
>>>  load_env
>>> fi
>>> set default="0"
>>> if [ "${prev_saved_entry}" ]; then
>>>  set saved_entry="${prev_saved_entry}"
>>>  save_env saved_entry
>>>  set prev_saved_entry=
>>>  save_env prev_saved_entry
>>>  set boot_once=true
>>> fi
>>>
>>> function savedefault {
>>>  if [ -z "${boot_once}" ]; then
>>>    saved_entry="${chosen}"
>>>    save_env saved_entry
>>>  fi
>>> }
>>>
>>> function load_video {
>>>  insmod vbe
>>>  insmod vga
>>>  insmod video_bochs
>>>  insmod video_cirrus
>>> }
>>>
>>> insmod raid
>>> insmod mdraid
>>> insmod part_msdos
>>> insmod part_msdos
>>>
>>> ... and that's all. The last line when grub-mkconfig prints to stdout is:
>>>
>>> /usr/sbin/grub-probe: error: unknown filesystem.
>>>
>>>
>>> All the partitions use ext4. Doesn't grub know about ext4?
>>
>> What filesystems did you mount before chrooting?
>
> yun:/mnt# mount
> /dev/sde1 on / type ext3 (rw,errors=remount-ro)
> tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
> proc on /proc type proc (rw,noexec,nosuid,nodev)
> sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
> udev on /dev type tmpfs (rw,mode=0755)
> tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
> devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
> /dev/md0p7 on /tmp type ext4 (rw,errors=remount-ro)
> /dev/md0p3 on /usr type ext4 (rw)
> /dev/md0p5 on /var type ext4 (rw,errors=remount-ro)
> /dev/md126 on /home type ext4 (rw,errors=remount-ro)
> /dev/md0p6 on /opt type ext4 (ro)
> /dev/md0p2 on /mnt/raid type ext4 (rw)
> /usr on /mnt/raid/usr type none (rw,bind)
> /var on /mnt/raid/var type none (rw,bind)
> /tmp on /mnt/raid/tmp type none (rw,bind)
> /dev on /mnt/raid/dev type none (rw,bind)
> /dev/shm on /mnt/raid/dev/shm type none (rw,bind)
> /proc on /mnt/raid/proc type none (rw,bind)
> /sys on /mnt/raid/sys type none (rw,bind)
> /mnt/tst on /mnt/raid/mnt/tst type none (rw,bind)
>
> yun:/mnt# fdisk -lu
>
> Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
> 81 heads, 63 sectors/track, 765633 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: 0x52f0b1be
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdb1            2048  3907029167  1953513560   da  Non-FS data
>
> Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes
> 81 heads, 63 sectors/track, 765633 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: 0x209529d4
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1            2048  3907029167  1953513560   da  Non-FS data
>
> Disk /dev/sdd: 500.1 GB, 500107862016 bytes
> 81 heads, 63 sectors/track, 191411 cylinders, total 976773168 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: 0x0009e00f
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdd1            2048   976773167   488385560   da  Non-FS data
>
> Disk /dev/sde: 200.0 GB, 200048565760 bytes
> 255 heads, 63 sectors/track, 24321 cylinders, total 390719855 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: 0xf7f1999d
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sde1   *          63     1959929      979933+  83  Linux
> /dev/sde2         1959930    64452779    31246425   82  Linux swap / Solaris
> /dev/sde3        64452780   189454544    62500882+  83  Linux
> /dev/sde4       189454606   390716864   100631129+   5  Extended
> /dev/sde5       189454608   314456309    62500851   83  Linux
> /dev/sde6       314456373   390716864    38130246   83  Linux
>
> Disk /dev/sdf: 500.1 GB, 500107862016 bytes
> 81 heads, 63 sectors/track, 191411 cylinders, total 976773168 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: 0x00006bbb
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdf1            2048   976773167   488385560   da  Non-FS data
>
> Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
> 81 heads, 63 sectors/track, 765633 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: 0x585ee666
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sda1            2048  3907029167  1953513560   da  Non-FS data
>
> Disk /dev/md0: 500.1 GB, 500105625600 bytes
> 2 heads, 4 sectors/track, 122096100 cylinders, total 976768800 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: 0x485cd85b
>
>    Device Boot      Start         End      Blocks   Id  System
> /dev/md0p1            2048   134219775    67108864   82  Linux swap / Solaris
> /dev/md0p2   *   134219776   144705535     5242880   83  Linux
> /dev/md0p3       144705536   354420735   104857600   83  Linux
> /dev/md0p4       354420736   976768799   311174032    5  Extended
> /dev/md0p5       354422784   564137983   104857600   83  Linux
> /dev/md0p6       564140032   773855231   104857600   83  Linux
> /dev/md0p7       773857280   976768799   101455760   83  Linux
>
> Disk /dev/md126: 4000.8 GB, 4000792444928 bytes
> 2 heads, 4 sectors/track, 976755968 cylinders, total 7814047744
> sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
> Disk identifier: 0x00000000
>
> Disk /dev/md126 doesn't contain a valid partition table
>
> yun:/mnt# cat /proc/mdstat
> Personalities : [raid1] [raid6] [raid5] [raid4]
> md126 : active raid5 sdc1[0] sda1[3] sdb1[1]
>      3907023872 blocks super 1.2 level 5, 512k chunk, algorithm 2
>      [3/3] [UUU]
>
> md0 : active raid1 sdd1[0] sdf1[1]
>      488384400 blocks super 1.2 [2/2] [UU]
>
> unused devices: <none>
>
> yun:/mnt#
>
> It's supposed to become a very simple setup with two RAID arrays,
> i. e. a RAID1 for the system partitions and a RAID5 for /home. Once I
> get more SATA cables, I can connect another 300GB SATA disk and the
> DVD drives. I want to retire the IDE disk (/dev/sde).
>
> If I have to, I can make a small partition on the other SATA disk
> (which isn't connected yet and which I don't really need atm) to use
> for /boot, but that disk is likely to be the next one to fail.

1. I forgot to ask earlier, are you running "grub-install /dev/sdd"
(and/or sdf)?

2. Differences with setups that I've used:

2.a. I've never used the mdadm mdp option (I use md) or the fdisk da
option (I use fd).

2.b. You're booted from sde1 and mount the md0p2 install's /tmp, /usr,
/var, /home, and /opt over the sde1 install's equivalents before
bind-mounting to the "/mnt/raid" mount of md0p2, and chrooting to it.
I would've mounted them directly to "/mnt/raid".

2.c. I only bind-mount /dev and create "normal" mounts for /dev/shm,
/proc, and /sys.

I'm not sure if any of the points in (2) are causing your
"grub-install" failure but thought that I'd highlight them anyway.