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nethbar 05-29-2007 10:49 AM

Want to move LVM installation to RAID5 array - how do I get it to boot?
 
I tried to setup LVM on RAID during the Ubuntu 7.04 installation but I was never able to get it to work, kept giving me this error:

Code:

Error informing the kernel about modifications to partition /dev/md/0p1
--Invalid argument.
This means Linux won't know about changes you made to /dev/md/0p1 until you reboot
-- so you shouldn't use it in any way before rebooting

So I gave up (tried wiping the disks, setting up the RAID flags in advance...) and went ahead and instead using LVM, figuring it would be easier to move it on to an array afterwards.

I have 4 SCSI drives, all identical - 18 GB Quantums. / is on /dev/sdd1, sd[abc]1 are setup in an empty RAID5 array, /dev/md0.

I'd like to move everything over to /dev/md0 and put /dev/sdd1 and add as a hot spare.

I've read a lot of really helpful stuff for situations not much like mine. I've read a lot of howtos and would be happy with RTFM if I could just find the right manual. There's a LOT of dated stuff on raidtools and how to boot from RAID1. There are two points I'm really stuck on (the rest I believe I can muck through, it's all pretty new to me):

1. I can't seem to format the boot partition I need on /dev/md0. I can create a 256MB partition /dev/md0p1 in cfdisk and write the changes but when I go
Code:

mrmr@ettin:/$ sudo mke2fs -j /dev/md0p1
mke2fs 1.40-WIP (14-Nov-2006)
Could not stat /dev/md0p1 --- No such file or directory

The device apparently does not exist; did you specify it correctly?

that's what I get.

2. Once I do have a boot partition setup properly on my array, how do I copy over the boot information so it will properly boot? I know 'cp -r /boot /(destination)' will get the files over but how do get GRUB to look in the right spot on the LVM?

Here's some helpful? output:
sudo fdisk -l
Code:

Disk /dev/sda: 18.3 GB, 18373206016 bytes
255 heads, 63 sectors/track, 2233 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sda1  *          1        2233    17936541  fd  Linux raid autodetect

Disk /dev/sdb: 18.3 GB, 18373206016 bytes
255 heads, 63 sectors/track, 2233 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sdb1  *          1        2233    17936541  fd  Linux raid autodetect

Disk /dev/sdc: 18.3 GB, 18373206016 bytes
255 heads, 63 sectors/track, 2233 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sdc1  *          1        2233    17936541  fd  Linux raid autodetect

Disk /dev/sdd: 18.3 GB, 18373206016 bytes
255 heads, 63 sectors/track, 2233 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sdd1  *          1          31      248976  83  Linux
/dev/sdd2              32        2233    17687565    5  Extended
/dev/sdd5              32        2233    17687533+  8e  Linux LVM

Disk /dev/md0: 36.7 GB, 36733845504 bytes
2 heads, 4 sectors/track, 8968224 cylinders
Units = cylinders of 8 * 512 = 4096 bytes

    Device Boot      Start        End      Blocks  Id  System
/dev/md0p1  *          1      62253      249010  83  Linux

cat /etc/fstab
Code:

# /etc/fstab: static file system information.
#
# <file system> <mount point>  <type>  <options>      <dump>  <pass>
proc            /proc          proc    defaults        0      0
/dev/mapper/ettin-root /              ext3    defaults,errors=remount-ro 0      1
# /dev/sdd1
UUID=1c481e0a-0622-4c41-a5e2-724f30ab554e /boot          ext3    defaults        0      2
/dev/mapper/ettin-swap_1 none            swap    sw              0      0
/dev/scd0      /media/cdrom0  udf,iso9660 user,noauto    0      0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0      0

sudo mdadm --detail /dev/mdo
Code:

/dev/md0:
        Version : 00.90.03
  Creation Time : Mon May 28 15:15:58 2007
    Raid Level : raid5
    Array Size : 35872896 (34.21 GiB 36.73 GB)
    Device Size : 17936448 (17.11 GiB 18.37 GB)
  Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Mon May 28 18:50:12 2007
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

        Layout : left-symmetric
    Chunk Size : 64K

          UUID : 29827358:01a00be2:be10abfe:aadb887b (local to host ettin)
        Events : 0.8

    Number  Major  Minor  RaidDevice State
      0      8        1        0      active sync  /dev/sda1
      1      8      17        1      active sync  /dev/sdb1
      2      8      33        2      active sync  /dev/sdc1

here's the default entry for GRUB
Code:

title          Ubuntu, kernel 2.6.20-15-generic
root            (hd3,0)
kernel          /vmlinuz-2.6.20-15-generic root=/dev/mapper/ettin-root ro quiet splash
initrd          /initrd.img-2.6.20-15-generic
quiet
savedefault

Thanks for looking!


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