SUMMARY: How to recover corrupted boot device

From: Anil Khullar, Computer Center <Anil.Khullar_at_mailhub.gc.cuny.edu>
Date: Tue, 10 Sep 1996 13:39:42 -0400 (EDT)

Hi,
        Thanks to the folks on the list, and Digital Unix Support, I was
able to recover from a boot_disk crash.

Thanks -
Dave Parker djp_at_unx.dec.com
Javier Aida <jaida_at_gmd.com.pe>
Harinder Singh <singhh_at_vrinet.com>
and Digital Support folks.

Note 1: In the Installation Guide (D3.2C) (Part No: AA-PS2DF-TE) Section
        7.7.2, it wrongly states the following line

 # mkfdmn -t rz57 /dev/rrz0a root_domain ( it should be /dev/rz0a)

Note 2: The first section is documented, however the second and third
sections needed triage with DU Software support.

---------------------------
This what I did to restore my root device (rz3)

 Boot from the CD-ROM version 3.2C of OS
>>> boot dka400

1. select the "3" option (system administration) from INstall menu
This got me to # prompt. At this point it does not know of any drives

# cd /dev
# ./MAKEDEV rz3 tz5 (for boot drive and tape drive)

# disklabel -rw -t advfs rz3 rz26l (create a label for the new drive)
# mkfdmn rz3a root_domain
# mkfset root_domain root
# mount -t advfs root_domain#root /mnt
# cd /mnt
# vrestore -xf /dev/nrmt0h

2. At this point I halted the system and rebooted single user

>>> boot -fl i

Type vmunix for options.
# /sbin/bcheckrc

This will produce errors for the /usr and related filesystems because this
Advfs data does not exist on the partition yet. Also using the mkfdmn for
usr_domain will give errors because entry for it exists in /etc/fdmns

# /sbin/rmfdmn usr_domain (I had more than one partition devoted to /usr)
# mkfdmn /dev/rz3h usr_domain (recreate the first usr partition)
# mkfset usr_domain usr
# mkfset usr_domain local
# mount -t advfs usr_domain#usr /usr
# cd /usr
# vrestore -xvf /dev/nrmt0h

3. At this point this partition is nearly full. I need to do an addvol
but the commmand is in /usr/sbin, and moreover addvol needs ADVFS-UTILITIES
license PAKs to been in kernel memory. So I reboot and immediately
bring it to single user mode.

Then
# /usr/sbin/addvol /dev/rz2d usr_domain

(Note: If the primary device is corrupted in a file_domain, In my case
/dev/rz3h, then data in all partitions in that domain are
unrecoverable)

I rebooted again, and restored /usr/local from the remaining dump.
In my case fortunately /var and all other partitions are on seperate
disks, which helped.

Thanks once again.

anil

Original Question:
>
>Hi,
> I had an ALphaServer 1000 (DU3.2d-1)crash over the weekend due
>to ADVFS EXCEPTION error. The machine will not boot. The boot disk is
>aparently corrupted. I'm waiting for DEC Field Engineer to come and
>replace the drive. I do have a very recent full vdump of /, but was
>not able to find a step-by-step recovery procedure. I was told by
>Software support that such an instruction does exist (I could not find
>it in BOOKREADER ?). Where should I be looking ? Or will someone be
>kind enough to e-mail the instructions if they are not lengthy.
>
>Thanks in advance
>
>anil khullar
>
>
Received on Tue Sep 10 1996 - 20:35:49 NZST

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