wiki:TipAndDoc/storage/RAID

Version 28 (modified by mitty, 12 years ago) (diff)

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  1. boot loader
    1. lilo
    2. GRUB
      1. Ubuntu
  2. mdadm
    1. Ubuntu
      1. dpkg-reconfigure mdadm
  3. mount
    1. duplicate uuid on mount

    boot loader

    lilo

    • ファイルシステムにXFSを使う等で、OSインストール時にliloを選択した場合はデフォルトで全てのミラーdiskのMBRにliloがインストールされる模様 (Ubuntu 8.04 Hardy)
      • attachment:ubuntu-lilo-raid1.png​
      • /etc/lilo.conf (snip) 
        # Specifies the boot device.  This is where Lilo installs its boot
# block.  It can be either a partition, or the raw device, in which
# case it installs in the MBR, and will overwrite the current MBR.
#
boot=/dev/md1

# This option may be needed for some software RAID installs.
#
raid-extra-boot=mbr-only

# Specifies the location of the map file
#
map=/boot/map

# Specifies the number of deciseconds (0.1 seconds) LILO should
# wait before booting the first image.
#
delay=20

#
# Boot up Linux by default.
#
default=Linux

image=/vmlinuz
        label=Linux
        read-only
#       restricted
#       alias=1
        append="root=/dev/md1  "
        initrd=/initrd.img

image=/vmlinuz.old
        label=LinuxOLD
        read-only
        optional
#       restricted
#       alias=2
        append="root=/dev/md1  "
        initrd=/initrd.img.old
    • 少なくともdiskの先頭10MBは同一
      1. sudo dd if=/dev/sda of=sda count=10240 bs=1024
      2. sudo dd if=/dev/sda of=sdb count=10240 bs=1024
      3. sha1sum sd? 
        642aace4e9239c85a011c4f6d643786b78e8e454  sda
642aace4e9239c85a011c4f6d643786b78e8e454  sdb
    • RAID5でどうなるかは不明

    GRUB

    • GRUBのコマンドについて
    • この情報によると、RAID時にGRUBコマンドのデファクトとなっている「install」コマンドではなく「setup」コマンドがbetter？
      • ネット上で主に見つかる手順
        1. df /boot 
          Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/md1               1450192    605532    771572  44% /
        2. grep md1 /proc/mdstat 
          md1 : active raid1 sda2[0] sdb1[2](S) sdc2[1]
        3. sudo grub 
          grub> device (hd0) /dev/sdc
grub> root (hd0,1)
grub> install /boot/grub/stage1 (hd0) /boot/grub/stage2 p /boot/grub/grub.conf
        • こちらの方がbetter？ (未検証) 
          grub> root (hd2,1)
grub> setup (hd2)

    Ubuntu

    • liloと同様に、二つ目のMBRにもGRUBが自動でセットされる模様。GRUB installは不要？
      • /boot/grub/menu.lst (snip) 
        ## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not use 'savedefault' or your
# array will desync and will not let you boot your system.
default         0

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout         3

## hiddenmenu
# Hides the menu by default (press ESC to see the menu)
hiddenmenu

title           Ubuntu 8.04.2, kernel 2.6.24-24-server
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.24-24-server root=/dev/md1 ro quiet splash
initrd          /boot/initrd.img-2.6.24-24-server

    mdadm

    Ubuntu

    • /etc/initramfs-tools/conf.d/mdadm 
      # BOOT_DEGRADED:
# Do you want to boot your system if a RAID providing your root filesystem
# becomes degraded?
#
# Running a system with a degraded RAID could result in permanent data loss
# if it suffers another hardware fault.
#
# However, you might answer "yes" if this system is a server, expected to
# tolerate hardware faults and boot unattended.

BOOT_DEGRADED=false
      • viなどでこのファイルを直接編集しても、反映されない模様。以下のdpkg-reconfigure mdadmから設定する必要がある。
    • /etc/mdadm/mdadm.conf 
      # instruct the monitoring daemon where to send mail alerts
MAILADDR root
    • /etc/default/mdadm 
      # AUTOCHECK:
#   should mdadm run periodic redundancy checks over your arrays? See
#   /etc/cron.d/mdadm.
AUTOCHECK=true

# START_DAEMON:
#   should mdadm start the MD monitoring daemon during boot?
START_DAEMON=true
      • /etc/cron.d/mdadm 
        # By default, run at 01:06 on every Sunday, but do nothing unless the day of
# the month is less than or equal to 7. Thus, only run on the first Sunday of
# each month. crontab(5) sucks, unfortunately, in this regard; therefore this
# hack (see #380425).
6 1 * * 0 root [ -x /usr/share/mdadm/checkarray ] && [ $(date +\%d) -le 7 ] && /usr/share/mdadm/checkarray --cron --all --quiet

    dpkg-reconfigure mdadm

    • [ ... ] がデフォルト値
    • sudo dpkg-reconfigure mdadm
      1. /etc/default/mdadm AUTOCHECK 
         ┌───────────────────────────┤ Configuring mdadm ├
 │                                                                           │
 │ If your kernel supports it (>> 2.6.14), mdadm can periodically check the  │
 │ redundancy of your MD arrays (RAIDs). This may be a resource-intensive    │
 │ process, depending on your setup, but it could help prevent rare cases    │
 │ of data loss. Note that this is a read-only check unless errors are       │
 │ found; if errors are found, mdadm will try to correct them, which may     │
 │ result in write access to the media.                                      │
 │                                                                           │
 │ The default, if turned on, is to run the checks on the first Sunday of    │
 │ every month at 01:06 o'clock.                                             │
 │                                                                           │
 │ Should mdadm run monthly redundancy checks of the MD arrays?              │
 │                                                                           │
 │                   [<Yes>]                      <No>                       │
 │                                                                           │
 └──────────────────────────────────────
      2. /etc/default/mdadm START_DAEMON 
          ┌──────────────────────────┤ Configuring mdadm ├
─│                                                                         │
  │ The MD (RAID) monitor daemon sends email notifications in response to   │
  │ important MD events (such as a disk failure). You probably want to      │
  │ enable it.                                                              │
  │                                                                         │
  │ Do you want to start the MD monitoring daemon?                          │
  │                                                                         │
  │                   [<Yes>]                      <No>                     │
  │                                                                         │
  └──────────────────────────────────────
      3. /etc/mdadm/mdadm.conf MAILADDR 
           ┌─────────────────────────┤ Configuring mdadm ├─
─ │ Please enter the email address of the user who should get the email   │
   │ notification for important MD events.                                 │
   │                                                                       │
   │ Recipient for email notifications:                                    │
   │                                                                       │
   │ root_________________________________________________________________ │
   │                                                                       │
   │                                <Ok>                                   │
   │                                                                       │
   └─────────────────────────────────────
      4. /etc/initramfs-tools/conf.d/mdadm BOOT_DEGRADED 
         ┌───────────────────────────┤ Configuring mdadm ├
 │                                                                           │
 │ If your root filesystem is on a RAID, and a disk is missing at boot, it   │
 │ can either boot with the degraded array, or hold the system at a          │
 │ recovery shell.                                                           │
 │                                                                           │
 │ Running a system with a degraded RAID could result in permanent data      │
 │ loss if it suffers another hardware fault.                                │
 │                                                                           │
 │ If you do not have access to the server console to use the recovery       │
 │ shell, you might answer "yes" to enable the system to boot unattended.    │
 │                                                                           │
 │ Do you want to boot your system if your RAID becomes degraded?            │
 │                                                                           │
 │                    <Yes>                      [<No>]                      │
 │                                                                           │
 └──────────────────────────────────────
      • apply settings... (liloを使っている場合) 
         * Stopping MD monitoring service mdadm --monitor                        [ OK ]
Generating array device nodes... done.
 Removing any system startup links for /etc/init.d/mdadm-raid ...
update-initramfs: Generating /boot/initrd.img-2.6.24-24-server
Warning: LBA32 addressing assumed
Added Linux *
Added LinuxOLD
The Master boot record of  /dev/sda  has been updated.
Warning: /dev/sdb is not on the first disk
The Master boot record of  /dev/sdb  has been updated.
2 warnings were issued.
 * Starting MD monitoring service mdadm --monitor                        [ OK ]

    mount

    duplicate uuid on mount

    • /dev/md2 (XFS) -> RAID1 /dev/sda2, /dev/sdb2
    • on Knoppix 
      # mount /dev/sda2 /mnt/sda -r -t xfs
# mount /dev/sdb2 /mnt/sdb -r -t xfs
mount: wrong fs type, bad option, bad superblock on /dev/sdb2,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
# dmesg | tail
XFS: Filesystem sdb2 has duplicate UUID - can't mount
    • => ​Re: duplicate uuid on mount 
      There is also the "nouuid" option to mount:
mount -t xfs -o nouuid /dev/sdc5 /mnt/tmp
This tells the kernel to ignore duplicate UUID.

      # mount /dev/sdb2 /mnt/sdb -r -t xfs -o nouuid
# mount
/dev/sda2 on /media/sda type xfs (ro,ikeep,noquota)
/dev/sdb2 on /media/sdb type xfs (ro,nouuid,noquota)

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