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Creating an emergency boot floppy disk set (OpenServer)

If you have Edge installed you do not need to use this guide. See Creating root/boot floppies.

The emergency boot floppy disk set allows you to recover your system in the event of a catastrophic system failure (when the computer does not respond to your attempts to start it). Use these floppy disks to restore a corrupted root filesystem without reinstalling the system.

If you have more than one system, you must make one emergency boot floppy disk set for each machine. Label each set with the machine name and store the floppy disks in a safe and secure place near the computer.

WARNING: If you use the wrong floppy disk set on a machine, it could cause further corruption.

These tasks are associated with creating an emergency boot floppy disk set:

  1. ``Configuring the floppy disks''
  2. ``Adding files to the root floppy disk''
  3. ``Testing your emergency boot floppy disk set''
  4. ``Reading backups''
  5. ``Booting from the hard disk''

Configuring the floppy disks

NOTE: If you have less than 16MB of RAM installed, you may need shut down the system and bring it up in single-user mode before creating your emergency boot floppy disk set. This is because the root floppy disk creates a RAM disk that requires 2MB of contiguous memory (a single block of memory instead of multiple segments that add up to 2MB). When there is insufficient contiguous memory to create the RAM disk, you see the message: /dev/ramfs: cannot open.

  1. Log in as root.

  2. Use the Floppy Manager located in the Filesystems directory of the SCOadmin hierarchy, or enter this command: 

       mkdev fd

  3. At the main menu, enter 2 to create the emergency boot floppy disk set.

  4. When prompted, indicate the type of disk drive you are using; unless you have a 2.88MB drive, enter 2.

  5. If you have more than one floppy disk drive, you are prompted for the drive that you are using to create the floppy disk. Enter either 0 (for the primary drive) or 1 (for the secondary drive).

    Note: You MUST create the root/boot set on the PRIMARY Floppy.

  6. When prompted for the type of filesystem, select 1 to create the root floppy disk. If you are creating a single boot/root floppy disk, select 3.

  7. When prompted, insert a blank floppy disk and press <Enter>.

  8. When prompted to format the floppy disk:

    If the floppy disk is already formatted, enter n. The filesystem is then created immediately.

    If the floppy disk is not formatted, enter y. You see the track and head numbers count up as the floppy disk is formatted. (If the /etc/default/format file contains the string VERIFY=Y, the format is also verified.)

  9. A filesystem is created on the floppy disk and system files are copied over to a RAM disk for compression.

  10. . When you see the message:

    Do you want a shell escape to place extra files on the root filesystem? (y/n)

    If you want to place additional files on the disk, enter y and follow the instructions in ``Adding files to the root floppy disk''. Otherwise enter n. If you are creating a single boot/root floppy disk, skip to step 13.

    NOTE: Disk space on the emergency boot floppy disks is limited and only critical utilities are loaded. Where possible, additional utilities such as tar(C) are copied when space permits.

  11. The filesystem is checked using fsck(ADM) and displays messages similar to the filesystem check displayed at boot time. You are notified when the the floppy disk is ready. Remove the floppy disk from the drive, and label it ``root'' and include the machine name. Put a write-protect tab on it so that you do not accidentally erase the information on the floppy disk.

  12. Press <Enter> to continue and you are returned to the filesystem type menu. Enter 2 to create the boot floppy disk.

  13. You have two options for the boot floppy disk: a system-specific disk that contains the same kernel that is currently on your system, or a smaller ``generic'' kernel that has fewer drivers linked in. If your current kernel is too large to fit on the disk, you will be warned and you will have to select the generic disk.

  14. Insert the floppy disk and respond to the prompts as you did for inserting and formatting the root floppy disk.

  15. The boot floppy disk is created and you see messages as files are copied to the disk. Then, the filesystem is checked using fsck(ADM). When complete, be sure and label it as you did with the root disk.

  16. Follow the procedure in the ``Testing your emergency boot floppy disk set'' section to verify that you can boot your system and access backups using your boot and root floppy disks.

Store your emergency boot floppy disk set (or single boot/root floppy disk) in a safe and secure place. Make sure they are easily accessible; you will need them if your system becomes corrupted and is no longer bootable.

Adding files to the root floppy disk

Note: You will not normally need to use this option.

If you respond y to the prompt for a shell escape during root floppy disk creation, you see:

You can copy files into /mnt to customize your root filesystem floppy. After you finish, type "exit 0" to continue. You have n free blocks (512 bytes each) available on the floppy.

The command prompt is <bootroot>.

If you have enough free space available, you can copy additional files to the root floppy disk. For example, to copy the file /usr/pest to the disk, you would enter: 

cp /usr/pest /mnt/usr

When your additions are complete, enter exit 0 at the bootroot> prompt.

Testing your emergency boot floppy disk set

After you create your emergency boot floppy disk set, verify that you can boot from it and read from backups:

  1. Log in as root.

  2. Shut down the system by entering /etc/shutdown.

  3. At the prompt to reboot, insert your boot floppy disk in the floppy disk drive and press <Enter>.

  4. At the Boot: prompt, press <Enter> to boot from the floppy disk.

  5. When prompted, insert the root floppy disk and press <Enter>.

  6. When you see the system prompt, verify that you can access your floppy disk or tape drive; follow the steps in ``Reading backups''.

Reading backups

At the end of the installation procedure, you made a complete backup of your system. If you have not already backed up your system, do it now using the instructions in ``Running unscheduled filesystem backups'' in the System Administration Guide.

Verify that you can read from this backup after booting from the emergency boot floppy disk set.

NOTE: Unless you have a second floppy disk drive, you can only read from tape backups when you boot from the floppy disk drive with your boot and root floppy disks.

  1. Make sure that the root floppy disk is in the drive.

  2. List the contents of the backup: 

       cpio -itvcB -I /dev/rct0

    NOTE: You must be able to access your backup tape volumes when you boot from the emergency boot floppy disk set. If you cannot, follow the steps in the next section, ``Booting from the hard disk''.

  3. Once you are satisfied that you can read backups after booting from your emergency boot floppy disk set, reboot the system from the hard disk by entering /etc/haltsys at the prompt.

  4. When you see the message to reboot, remove the floppy disk from the drive and press <Enter>.

  5. At the Boot: prompt, press <Enter> to boot from the hard drive.

For information on using your emergency boot floppy disk set to access and restore a corrupted root filesystem, see ``Restoring a corrupted root filesystem''.

Booting from the hard disk

If you experience problems booting your system with the emergency boot floppy disk set or you cannot access your backup volumes when you boot with these floppy disks, reboot the system from the hard drive:

  1. Press the computer ``reset'' button, or turn the power off, then on.

  2. At the Boot: prompt, press <Enter> to reboot from the hard drive.

  3. If you have trouble with your floppy disks, try ``Configuring the floppy disks'' again.