unknown device with lvm

idris · 02-19-2005, 10:33 AM

I had a working LVM setup with two physical volumes (entire disks) in one volume group, and a separate system disk. Then the processor died and I had to change it and the motherboard, and in the process the lvm disks had to be moved from hde and hdf to hdc and hdd. Shouldn't be a problem, right?

However, now pvscan doesn't find /dev/hdd correctly but calls it an unknown device, and
all lvm tools complain about not finding its uuid:

indigo:~# vgscan
Reading all physical volumes. This may take a while...
Couldn't find device with uuid 'p4YzIv-Ntiq-NxPo-J4tw-UDXF-4w4V-FiXqLl'.
Couldn't find all physical volumes for volume group storage.
Volume group "storage" not found
indigo:~# pvscan
Couldn't find device with uuid 'p4YzIv-Ntiq-NxPo-J4tw-UDXF-4w4V-FiXqLl'.
PV unknown device VG storage lvm2 [233.72 GB / 0 free]
PV /dev/hdc VG storage lvm2 [233.75 GB / 768.00 MB free]
Total: 2 [467.47 GB] / in use: 2 [467.47 GB] / in no VG: 0 [0 ]

Attempting to fix this, I did something rather stupid: I created a new physical volume on /dev/hdd with pvcreate -ff, and now pvdisplay returns three entries:

indigo:~# pvdisplay
Couldn't find device with uuid 'p4YzIv-Ntiq-NxPo-J4tw-UDXF-4w4V-FiXqLl'.
--- Physical volume ---
PV Name unknown device
VG Name storage
PV Size 233.72 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 7479
Free PE 0
Allocated PE 7479
PV UUID p4YzIv-Ntiq-NxPo-J4tw-UDXF-4w4V-FiXqLl

--- Physical volume ---
PV Name /dev/hdc
VG Name storage
PV Size 233.75 GB / not usable 0
Allocatable yes
PE Size (KByte) 32768
Total PE 7480
Free PE 24
Allocated PE 7456
PV UUID 7DNebf-aFtA-7bCq-ywZq-qJ32-DAj8-UU6hK5

--- NEW Physical volume ---
PV Name /dev/hdd
VG Name
PV Size 233.76 GB
Allocatable NO
PE Size (KByte) 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 0deIQh-yFLO-KEb2-zn06-7fee-uKmY-UrYlRg

Please, is there's any way to fix this? I'm afraid of tinkering with
it more without knowing what I'm doing since I'd really rather not lose the
data (it's only partially backed up...)

Idris in trouble

idris · 02-21-2005, 01:54 PM

Please, does anyone have any pointers on how to proceed? I'd really really appreciate it (can you tell I'm getting desperate)

Idris

ManishChopra · 05-28-2005, 09:22 AM

This is somewhat related to what Idris has gone thru but is relatively a simpler problem than his. Well for Idris, its a long gone problems, and if is'nt able to add these volumes to any other VG, then bad luck.

I have a small query on LVM's pvcreate command, if anyone might have an idea on it.

Can we undo the change caused by command pvcreate /dev/hda8 that was a Win 32 FAT partition, in order to get back the lost information ?

Originally this command was intended to be as :

[root@localhost]# pvcreate /dev/hdb8

However, it was a typo mistake that the command got executed on /dev/hda8, and that was a windows logical partition. The drive can be seen on windows, but does not show any information stored on it.

--------------------
Error displayed as :

G:\is not accessible

A device attached to the system is not functioning.

---------------------------------------------------

pvcreate has initialized /dev/hda8 as a physical volume, and I want to know if it can be un-done.

I have gone through all other related commands on LVM, but none seem to help me in this case.

e2fsadm(8), lvchange(8), lvcreate(8), lvdisplay(8),
lvextend(8), lvmchange(8), lvmdiskscan(8),
lvmcreate_initrd(8), lvmsadc(8), lvmsar(8),
lvreduce(8), lvremove(8), lvrename(8),
lvscan(8), pvchange(8), pvcreate(8), pvdata(8),
pvdisplay(8), pvmove(8), pvscan(8), vgcfgbackup(8),
vgcfgrestore(8), vgchange(8), vgck(8), vgcreate(8),
vgdisplay(8), vgexport(8), vgextend(8), vgimport(8),
vgmerge(8), vgmknodes(8), vgreduce(8), vgremove(8),
vgrename(8), vgscan(8), vgsplit(8)

From the above commands, pvmove is'nt an option on RHEL 3, hence no good.

If there are any workaround on this problem, please suggest me the way to resolve it, and get the contents of Win32 FAT partition.

Warm regards,

Manish Chopra
(Homepage www.TechTheRightWay.net)

(Formerly with IBM, for their technical support center, and currently researching on technology trends and scenarios changing the IT landscape. Have also appeared for RHCE exam today, without a pass.)

PS. Please help get the open source stabilized and standardized

Golovko · 06-20-2005, 09:59 PM

Missing drives in a volume group have caused me a lot of problems. If you just want to excommunicate the drive from your vg, the following works:

vgreduce --removemissing vg00

where vg00 is your vg. Of course this doesn't solve the problem of recovering any data on the pv you are removing.

Gol

PhillipHuang · 07-09-2007, 01:24 AM

Quote:

Missing drives in a volume group have caused me a lot of problems. If you just want to excommunicate the drive from your vg, the following works:

vgreduce --removemissing vg00

I'm now testing LVM-Mirror on CentOS4.5, and the package is lvm2-2.02.21. First, make /dev/sdf and /dev/sdg as pv, then build vg(named milan) across these two PVs. Create LVM-moirror by executing the following command:

Code:

# pvscan
  PV /dev/sdf   VG milan    lvm2 [30.00 GB / 29.90 GB free]
  PV /dev/sdg   VG milan    lvm2 [30.00 GB / 29.90 GB free]

# vgdisplay
  --- Volume group ---
  VG Name               milan
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  6
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               0
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               59.99 GB
  PE Size               4.00 MB
  Total PE              15358
  Alloc PE / Size       50 / 200.00 MB
  Free  PE / Size       15308 / 59.80 GB
  VG UUID               j0SkJN-5Y2A-PFm2-UJOA-srXO-DImb-fk3kUy

# lvcreate -L 100M -m1 -n mirror milan
# gfs_mkfs -p lock_dlm -t my_cluster:gfs -J 32M -j 2 /dev/milan/mirror
# mount -t gfs -o acl /dev/milan/mirror /mnt
# dd if=/dev/zero of=/mnt/1.iso bs=1M count=100

There will be creating 1.iso on the /dev/milan/mirror, What I want to do is verify the mirror function when one leg(underlying PV) crashes. Hence, I deactivate the lv(# lvchagne -an /dev/milan/mirror) first and destory the PV /dev/sdg by "mkfs.ext3 /dev/sdg".

Code:

# pvscan
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  PV unknown device   VG milan    lvm2 [30.00 GB / 29.90 GB free]
  PV /dev/sdg         VG milan    lvm2 [30.00 GB / 29.90 GB free]

# vgscan
  Reading all physical volumes.  This may take a while...
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  Couldn't find all physical volumes for volume group milan.
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  Couldn't find all physical volumes for volume group milan.
  Volume group "milan" not found

# lvscan
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  Couldn't find all physical volumes for volume group milan.
  Couldn't find device with uuid 'pQMQJ3-Rq3M-kQD9-M6DB-UWLi-Dyk4-3pWoa7'.
  Couldn't find all physical volumes for volume group milan.
  Volume group "milan" not found

As Golovko's comments, "vgreduce --removemissing milan" resolves the complains caused by lossing uuid. Activate the lv again:

Code:

# lvchange -ay /dev/milan/mirror

# pvscan
  PV /dev/sdf   VG milan    lvm2 [30.00 GB / 29.90 GB free]

# lvscan
  ACTIVE            '/dev/milan/mirror' [100.00 MB] inherit

# vgdisplay
--- Volume group ---
  VG Name               milan
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  12
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               30.00 GB
  PE Size               4.00 MB
  Total PE              7679
  Alloc PE / Size       25 / 100.00 MB
  Free  PE / Size       7654 / 29.90 GB
  VG UUID               j0SkJN-5Y2A-PFm2-UJOA-srXO-DImb-fk3kUy

Yes, "vgdisplay" shows there's only a Current PV, and it is really the another leg identified during creating LVM mirror:

Code:

# pvs -a
/dev/sdf     milan  lvm2 a-    30.00G 29.90G

mount this lv and find the 1.iso still exists, it indicates the mirror function runs well and the left lv is linear.

Hope this helpful when you meet the same issue.

Phillip