[linux-lvm] Error -154 can't get data from VG

[Bruno Kraychete da Costa]

Hi,

I'm writing from this hotmail account because my main machine is down. It 
has LVM, but after some problems, I cannot seem to get it up again. It's a 
SuSE 7.0 with kernel 2.4.0-test9. I was using LVM tools from suse 
distribution (lvm-0.8-131) and I'm not sure what patches they incorporated 
yet. I've got /dev/hda1 as my /boot (20MB) and all other partitions (/, 
home, var, tmp, swap) in the "rootvg" volume group.

Well, the history. I added a second HD to my machine and was planning to add 
it to my "rootvg". I actually made that far. I had this "data" LV and I was 
planning to make the new HD as my new "data". So I deactivated the current 
"data" LV, renamed it to "olddata" and created the new one in the new space 
coming from the new HD. Now, all I had to do was to copy the contents from 
"olddata" to "data". Whe I tried to mount /dev/rootvg/olddata, Linux froze. 
Tried SysReq, no go. Thinking a little, I remembered that I had forgotten to 
make that LV ("olddata") active again. Pushed reset button with my fingers 
crossed. The initrd failed to find my old /dev/rootvg/root LV. Crap! :(

Using SuSE7 boot disk, I managed to get a shell with LVM tools available. 
Vgscan and vgchanged succeeded and I could find the reason why my initrd 
failed. /dev/rootvg/root was not the "3a:00" device anymore. It was now 
"3a:01". Changed my initrd, umounted /dev/rootvg/root and rebooted. Got the 
same error again. I must have changed the wrong thing. No problems ... let's 
do it again. Booted from SuSE7 floppy to the shell with LVM tools and ... 
vgscan is now failing!! I'm getting "error -154 can't get data from physical 
volumes" or something like that. I cannot restore my /etc/lvmtab because my 
/etc dir is inside /dev/rootvg/root :( When I first booted from the boot 
disk and got LVM to work, it created /etc/lvmtab*, but it did so in the 
ramdisk. Given that, I have the following questions:

1) Why my Linux box froze when I (accidently) tried to mount an inactive LV? 
Shouldn't it throw some error message or something?

2) Why LVM didn't get corrupted when my box froze, but then got corrupted 
when I simply rebooted my box? :(

3) Since we have now some people that put their / in a volume group, isn't 
it a good idea to have LVM save VGDA backups outside a LVM volume group? 
(next time I can get my box to boot, I'll make a link from /etc/lvm* to 
/boot/lvm/lvm*, so VGDA data will be stored in /dev/hda1).

So, from your experience, do you think it is possible to get my data back 
from LVM's current state in my machine? All I have available is this shell 
with LVM tools from SuSE7 boot disk. :(

Thank you for your help,

Bruno.

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