[linux-lvm] LVM1 and a dying disk

[Rickard Olsson]

One of the disks in my /dev/files_vg vg have been making weird noises 
for a while. This vg is a JBOD with the following disks in it:


majestix root # pvscan
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- ACTIVE   PV "/dev/ide/host2/bus1/target0/lun0/disc" of VG "f2"
      [149 GB / 0 free]
pvscan -- inactive PV "/dev/ide/host2/bus0/target0/lun0/disc"  is in 
EXPORTED VG
  "files_vg" [149.03 GB / 0 free]
pvscan -- inactive PV "/dev/ide/host2/bus0/target1/lun0/disc"  is in 
EXPORTED VG
  "files_vg" [111.77 GB / 0 free]
pvscan -- inactive PV "/dev/ide/host0/bus1/target1/lun0/disc"  is in 
EXPORTED VG
  "files_vg" [93.14 GB / 0 free]
pvscan -- inactive PV "/dev/ide/host0/bus0/target0/lun0/disc"  is in 
EXPORTED VG
  "files_vg" [111.77 GB / 0 free]
pvscan -- inactive PV "/dev/ide/host0/bus0/target1/lun0/disc"  is in 
EXPORTED VG
  "files_vg" [93.14 GB / 0 free]
pvscan -- total: 6 [708 GB] / in use: 6 [708 GB] / in no VG: 0 [0]


Exported, you say? Yep. The machine that this vg was in suffered a fatal 
root filesystem corruption last friday - not related to this disk (I 
name it Black Friday, that same day my VW Passat dropped the rear 
muffler and my upstream ISP had some major network issues that still 
isn't resolved).
The f2 vg is the new vg I'm building to move data over to.


majestix root # vgscan
vgscan -- reading all physical volumes (this may take a while...)
vgscan -- found active volume group "f2"
vgscan -- ERROR "vg_read_with_pv_and_lv(): current PV" can't get data of 
volume
group "files_vgPV_EXP" from physical volume(s)
vgscan -- "/etc/lvmtab" and "/etc/lvmtab.d" successfully created
vgscan -- WARNING: This program does not do a VGDA backup of your volume 
groups


And devfs? Gentoo. Devfs is a major and total pain when trying to do a 
vgimport, listing 6 of those long paths on the command line is no fun. 
And, it doesn't work:


vgimport -- ERROR "pv_read(): PV identifier invalid" reading physical 
volume "/d
ev/ide/host0/bus1/target0/lun0/disc"


I did manage to export the vg before the machine died permanently. The 
backups I had of the root drive are older then the last major change to 
the vg (addition of the Seagate 160GB that shows up as 149.03 GB above). 
The troublesome disk is not showing in the pvscan, it's currently on 
/dev/ide/host0/bus1/target0/lun0/disc and a pvdata for it reveals:


majestix root # pvdata /dev/ide/host0/bus1/target0/lun0/disc
--- Physical volume ---
PV Name               /dev/ide/host0/bus1/target0/lun0/disc
VG Name               ÇD?
PV Size               111.79 GB [234441648 secs] / NOT usable 16.19 MB 
[LVM: 155 KB]
PV#                   0
PV Status             NOT available
Allocatable           yes (but full)
Cur LV                9306113
PE Size (KByte)       16384
Total PE              7153
Free PE               0
Allocated PE          7153
PV UUID               rDBb94-Kb8v-GMDa-HxIi-???

Segmentation fault


As you can see, not all fun and games.

Now, is there any way to re-initialize the pv data on the failing disk 
long enough to get it back into the vg and extract the data? The data 
left in the vg is not critically important (I started backing it up as 
soon as I noticed the noises), but it would be really nice to get it back.

I have considered pvcreating it, but I'm not sure how I'd get it into 
the vg afterwards - would a vgscan/vgchange suffice? Would a reiserfsck 
--rebuild_tree then prune the fs of anything that was on this disk?

    / Rickard Olsson,IT-Konsult/
   / Telefon: +46 70 635 01 42/
  / http://www.webhackande.se/