Repair boot sector after stupidly importing disk into vg? Post: 302189366

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Operating Systems AIX Repair boot sector after stupidly importing disk into vg? Post 302189366 by bakunin on Friday 25th of April 2008 02:30:47 PM

04-25-2008

Registered User

I have bad news for you: by importing the disk into the another VG you ruined the boot sector - the boot code for AIX 6.1 is now overwritten by the boot code of AIX 5.3, which is different. The only way to restore it is to have a running 6.1 system which could write the boot sector over the disk. (To put it in a slang you might be more familiar with: its like issuing a "fdisk /mbr" on the disk.)

Once you get your machine running again, "dd" is not the tool to do backups at all in AIX. There is a tool called "mksysb" which completely backs up all the system area into a bootable image. Use a tape device as destination and you have a perfectly bootable (and restorable) system image on tape. You can also use a file (even on the originating system) as destination, bot you will need an external boot device (such as a CD, another tape, etc.) to boot from that and only then use the file to restore the system.

You might also want to read about the Logical Volume Manager (LVM) of AIX. It is the oldest and most mature one in the industry and most of the other UNIX suppliers have either copied its concepts (Linux LVMs) or outright licensed it (like HP for example). You should never use the rootvg (the default volume group of any AIX system) for non-system data, for instance - and after reading up on the concepts behind LVM you will know why.

There is a very good systems administration tool, called "SMIT". Start it by issuing "smit" (better yet: "smitty", to start it in non-graphic mode) and you can do most of the systems administration tasks. SMIT uses standard system commands and you can even look at how its doing it by pressing "PF6" in one of the final screens. Up comes a window with the command SMIT would issue. This way you can learn a lot about how things are done in AIX.

I hope this helps.

bakunin

bakunin

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LEARN ABOUT POSIX

installgrub

installgrub(1M) 														   installgrub(1M)

NAME

       installgrub - install GRUB in a disk partition or a floppy

SYNOPSIS

       /sbin/installgrub [-fm] stage1 stage2 raw-device

       The installgrub command is an -only program. GRUB stands for GRand Unified Bootloader.

       installgrub  installs  GRUB  stage  1  and  stage  2  files on the boot area of a disk partition. If you specify the -m option, installgrub
       installs the stage 1 file on the master boot sector of the disk.

       The installgrub command accepts the following options:

       -f

	   Suppresses interaction when overwriting the master boot sector.

       -m

	   Installs GRUB stage1 on the master boot sector interactively.

       The installgrub command accepts the following operands:

       stage1

	   The name of the GRUB stage 1 file.

       stage2

	   The name of the GRUB stage 2 file.

       raw-device

	   The name of the device onto which GRUB code is to be installed. It must be a character device that is readable and writable.  For  disk
	   devices,  specify  the  slice  where  the  GRUB  menu  file	is  located.  (For Solaris it is the root slice.) For a floppy disk, it is
	   /dev/rdiskette.

       Example 1: Installing GRUB on a Hard Disk Slice

       The following command installs GRUB on a system where the root slice is c0d0s0:

       example# /sbin/installgrub /boot/grub/stage1 
		/boot/grub/stage2 /dev/rdsk/c0d0s0

       Example 2: Installing GRUB on a Floppy

       The following command installs GRUB on a formatted floppy:

       example# mount -F pcfs /dev/diskette /mnt
       # mkdir -p /mnt/boot/grub
       # cp /boot/grub/* /mnt/boot/grub
       # umount /mnt
       # cd /boot/grub
       # /sbin/installgrub stage1 stage2 /dev/rdiskette

       /boot/grub

	   Directory where GRUB files reside.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

       boot(1M), fdisk(1M), fmthard(1M), kernel(1M), attributes(5)

       Installing GRUB on the master boot sector (-m option) overrides any boot manager currently installed on the machine. The system will always
       boot the GRUB in the Solaris partition regardless of which fdisk partition is active.

								    24 May 2005 						   installgrub(1M)