data recovery from a disk with VxFS LVM (OS disk from a HP-UX 11i v2 server)

[ub2000]

Hi,

the disk drive of our rx2620 system broke and I have to try to recover some files from the /home folder. The disk was the result of a standard installation of "HP-UX 11i v2 Mission Critical Operating Environment" so the filesystem is VxFS with LVM.

The disk had signs of malfunction and broke entirely after a disk image was taken using the dd command (bad timing). But it appears dd had the chance to copy all bytes.

When the image is writen onto another disk and the server tries to boot from it, it fails shortly after the "Booting kernel..." message - one of the lines that appears on the screen before the machine automatically reboots is "panic: all VFS_MOUNTROOTs failed NEED DRIVERS ?????" and "Stack Trace... Function Name ... vfs_mountroot+0x1d0"

Putting the disk with the image into a running rx2620 runnung HP-UX 11i v2 does detect the disk, i.e.

ioscan -fn -C disk 

shows additional lines based on the disk (here only the new lines are shown:)

Class I H/W Path Driver S/W State H/W Type Description
=======================================================================
disk 6 0/1/1/1.2.0 sdisk CLAIMED DEVICE IBM IC35L073UCDY10-0
/dev/dsk/c3t2d0 /dev/rdsk/c3t2d0
/dev/dsk/c3t2d0s1 /dev/rdsk/c3t2d0s1
/dev/dsk/c3t2d0s2 /dev/rdsk/c3t2d0s2
/dev/dsk/c3t2d0s3 /dev/rdsk/c3t2d0s3

In order to copy as many files off the home directory as possible from somewhere on that disk I do not know what to try from here. Afaik for LVMs you need mapping information that was previously created with a command like this: vgexport -s -v -m /tmp/vg01.map vg01   -but we never backed up such a mapping file. I also don't know much about VxFS LVM.

Does anyone have any ideas how to recover as many files from that disk image as possible?

UB2000

[Patrick Wallek · Accepted solution]

You can import a disk into another system very easily.

If the disk was the only one in the VG, then just use the 'vgimport' command to import it.  In your example below you would import the c3t2d0s2 device since that is the one that would have been in the VG.

Here are the steps I would take since this is 11.23:

# mkdir /dev/vgimp

# mknod /dev/vgimp/group c 64 0x0f0000

(make sure you use a unique minor number for the group file)

# vgimport -v /dev/vgimp /dev/rdsk/c3t2d0s2

# vgchange -a y /dev/vgimp

If it is the /home LV you wish to get data off of, then you can attempt to mount it.  /home is typically LVOL5 in VG00, so try:

# mount /dev/vgimp/lvol5 /mnt

If you get a prompt about it needing an 'fsck' then do:

# fsck -y -o full /dev/vgimp/rlvol5

After that, try mounting it again.

Good luck.

[ub2000]

Thank you very much, this is what I have been looking for!

An interesting fact: In addition to your solution it was also possible to repair the dead disk by replacing the fuse on the drive. The fuse is an easily accessible but unobstrusive SMD component at the bottom of this drive model in the the corner of the PCB) - If anyone has a completely dead drive it's worth trying to replace replace the fuse. The hard part is to know which one of the small SMD squares is the fuse.