wiki:TipAndDoc/storage/RAID

Version 28 (modified by mitty, 8 years ago) (diff)

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    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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