Re: [gentoo-user] Re: How does grub assemble a RAID1 for / ??

[Mark Knecht]

On Sat, Apr 3, 2010 at 7:38 PM, Kerin Millar <kerframil@×××××.com> wrote:
> On 04/04/2010 02:01, Mark Knecht wrote:
>>
>> Tried changing root=/dev/md0. No change.
>>
>> The actual failure message is the fairly standard
>>
>> VFS - Unable to mount root fs on unknown-block(9,0)
>
> [snip]
>
>> CONFIG_MD_RAID1=y
>
> That's all that needs to be enabled within the RAID section of the kernel.
> However, all the other options that would normally be required to boot must
> also be compiled in statically for things to work as expected (ATA/SCSI
> controller driver, filesystem of choice, CONFIG_BLK_DEV_SD and so forth). It
> seems that you may have overlooked something. However, it's impossible to
> determine whether that's the case based on the information presented thus
> far.
>
> I would suggest that you double-check your .config in full, or present it
> here for review, along with the output of lspci -nn.
>
> Cheers,
>
> --Kerin

Hi Kerin,
   Happy for any help I can get.

   Instead of the whole .config file here's a diff. Remember that the
machine already boots non-RAID from /dev/sda and I'm trying to build
my first RAID boot on /dev/sdb & sdc.

   First, here's the RAID I would like to boot from:

keeper ~ # mdadm -A /dev/md3 /dev/sdb3 /dev/sdc3
mdadm: /dev/md3 has been started with 2 drives.
keeper ~ # mdadm --detail /dev/md3
/dev/md3:
        Version : 1.01
  Creation Time : Sat Apr  3 11:43:39 2010
     Raid Level : raid1
     Array Size : 52436092 (50.01 GiB 53.69 GB)
  Used Dev Size : 52436092 (50.01 GiB 53.69 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Sun Apr  4 06:40:54 2010
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : keeper:3  (local to host keeper)
           UUID : 6dcf5ddb:c4a2d5ea:ba59df10:f5473502
         Events : 3703

    Number   Major   Minor   RaidDevice State
       0       8       19        0      active sync   /dev/sdb3
       1       8       35        1      active sync   /dev/sdc3
keeper ~ # cat /proc/mdstat
Personalities : [raid1]
md3 : active raid1 sdb3[0] sdc3[1]
      52436092 blocks super 1.1 [2/2] [UU]

unused devices: <none>
keeper ~ #

Here's the diff of the running kernel without RAID and the kernel I
created while in the install chroot on the RAID device:

 keeper ~ # diff /usr/src/linux/.config /mnt/gentoo/usr/src/linux/.config
4c4
< # Mon Mar 29 01:02:31 2010
---
> # Sun Apr  4 06:28:53 2010
893,912c893,906
< CONFIG_MD_LINEAR=m
< CONFIG_MD_RAID0=m
< CONFIG_MD_RAID1=m
< CONFIG_MD_RAID10=m
< CONFIG_MD_RAID456=m
< # CONFIG_MULTICORE_RAID456 is not set
< CONFIG_MD_RAID6_PQ=m
< # CONFIG_ASYNC_RAID6_TEST is not set
< CONFIG_MD_MULTIPATH=m
< CONFIG_MD_FAULTY=m
< CONFIG_BLK_DEV_DM=m
< CONFIG_DM_DEBUG=y
< CONFIG_DM_CRYPT=m
< CONFIG_DM_SNAPSHOT=m
< CONFIG_DM_MIRROR=m
< # CONFIG_DM_LOG_USERSPACE is not set
< CONFIG_DM_ZERO=m
< CONFIG_DM_MULTIPATH=m
< # CONFIG_DM_MULTIPATH_QL is not set
< # CONFIG_DM_MULTIPATH_ST is not set
---
> # CONFIG_MD_LINEAR is not set
> CONFIG_MD_RAID0=y
> CONFIG_MD_RAID1=y
> # CONFIG_MD_RAID10 is not set
> # CONFIG_MD_RAID456 is not set
> # CONFIG_MD_MULTIPATH is not set
> # CONFIG_MD_FAULTY is not set
> CONFIG_BLK_DEV_DM=y
> # CONFIG_DM_DEBUG is not set
> # CONFIG_DM_CRYPT is not set
> # CONFIG_DM_SNAPSHOT is not set
> # CONFIG_DM_MIRROR is not set
> # CONFIG_DM_ZERO is not set
> # CONFIG_DM_MULTIPATH is not set
914,915c908,909
< CONFIG_DM_UEVENT=y
< CONFIG_BLK_DEV_DM_BBR=m
---
> # CONFIG_DM_UEVENT is not set
> # CONFIG_BLK_DEV_DM_BBR is not set
2293,2298d2286
< CONFIG_XOR_BLOCKS=m
< CONFIG_ASYNC_CORE=m
< CONFIG_ASYNC_MEMCPY=m
< CONFIG_ASYNC_XOR=m
< CONFIG_ASYNC_PQ=m
< CONFIG_ASYNC_RAID6_RECOV=m
keeper ~ #

   One additional thing I thought of last night was some message that
came up when I first built the RAID about the partitions having
metadata and to be sure that the bootloader understands metadata. In
the cool light of morning that seems fairly important. I am using
grub-static on this machine. I assumed this would be OK but possibly
it isn't?

   If rebuilding the RAID from scratch is important, or just makes
things more straight forward, then don't hesitate to suggest it and
I'll document the build step by step. This install isn't important.
I'm just doing it to learn how to do RAID and most importantly to test
the disk drives. I purchased other disk drives that aren't working
with RAID at all so I wanted to test these a bit before I did anything
real. The final install with be a 3 disk RAID1 but the 3rd drive
hasn't arrived yet so none of this is critically important.

   Thanks!

Cheers,
Mark