ERROR: V-3-24996: Unable to get disk layout version

[Vinod Udapudi]

Hi All,

We recently had server crash issue because of /stand/vmunix is missing. Finally we recovered the machine with IGNITE backup.

After this system is up and running but one mount is failing. Its not mounting.

UX:vxfs mount: ERROR: V-3-20003: Cannot open /dev/vg04/home: No such device or address
UX:vxfs mount: ERROR: V-3-24996: Unable to get disk layout version

lvdisplay /dev/vg04/home

"/dev/vg04/home": not a logical volume.

lvdisplay: Cannot display logical volume "/dev/vg04/home".

ll /dev/vg04/home
brw-r-----   1 root       sys         64 0x040010 Oct  9 23:53 /dev/vg04/home

swlist | grep -i vx
  Base-VXFS                             B.11.31        Base VxFS File System 4.1 Bundle for HP-UX
  Base-VxFS-50                          B.05.00.01     Veritas File System Bundle 5.0 for HP-UX

uname -r
B.11.31

model
ia64 hp server rx2620

Thanks in advance

Regards

Vinod

[Matti_Kurkela]

"Cannot open /dev/vg04/home: No such device or address" is the more important error message in this case.

The device node only translates the human-readable name "/dev/vg04/home" into parameters that are meaningful to the kernel: "block device, major number 64, minor number 0x040010". As the device node exists, the error message means the kernel does not currently have a device configured that would match those parameters: it's telling you "the device number you tried to access is not currently connected to anything at all."

(It's like looking up a telephone number from an old phonebook and getting a recorded message from the phone company: "The number you tried to reach is not connected. Please check the number and try again.")

Since major device number 64 is LVM1 (the major device number works like a telephone area code), the error ultimately means that the vg04 volume group might not be activated or maybe it is not even included in the current LVM configuration (/etc/lvmtab).

That would mean Ignite has failed to re-import the vg04 volume group, so you may have to import it manually.

What happens if you run these commands:

vgchange -a y vg04
strings /etc/lvmtab

The first command is likely to output an error message: what is the message?

The second command should output a list of all LVM1 volume groups and their PVs, whether activated or not. The list may include some garbage characters: that is normal, don't worry about it. (It is because /etc/lvmtab is actually a binary file, and we're using a general-purpose tool to view the human-readable parts of it.)

[Vinod Udapudi]

Thank you very much. Yes thats the problem looks like

vgchange -a y vg04
Volume group "/dev/vg04" is already active in requested mode.

strings /etc/lvmtab
/dev/vg00
/dev/disk/disk12_p2
/dev/vg05
/dev/disk/disk19
/dev/disk/disk16
/dev/disk/disk17
/dev/disk/disk18
/dev/vg04
/dev/disk/disk15
/dev/disk/disk14

only /home on VG04 is not mounting. Except /home rest all mounted fine.

But I cant see /home under vgdisplay -v /dev/vg04. So looks like VG04 is not reading /home LVol.

Any suggestions to fix this. I am thinking about existing data on /home.

Thank in advance

Regards

Vinod

[henry78]

Hi,
did you had any error during ignite recovery (see install.log) ?

regards
Tony78

[Matti_Kurkela · Accepted solution]

So the VG is currently active?

That might mean your Ignite backup was from the time before /dev/vg04/home was created. But in that case, I would not expect /etc/fstab to know about /dev/vg04/home either: with some sloppy admin practices, I guess /etc/fstab at the Ignite backup time might have been older than the current LVM configuration, but I don't immediately see how /etc/fstab that came from an Ignite restore could be newer than the LVM information.

So I have a feeling that I might be missing some important pieces of the puzzle. So you had a /stand filesystem failure, and an Ignite restore. Did you do any LVM-related recovery/changes after the Ignite restore? Did you import any VGs? If you did, did you use map files? Were the map files up to date, or old ones found from some random location?

Let's see what the VG looks like at the present time. Please show the output of this command:

vgdisplay -v vg04

 Let's also create a new map file for further inspection (and, maybe, recovery).

With the -p option, vgexport will just do a "preview" instead of actual export... but it will create the map file, which is exactly what we need.

vgexport -v -s -p -m /tmp/vg04-broken.map vg04

 Please attach the /tmp/vg04-broken.map file to this thread, too.

From the device node, we know that the missing LV should have ID 0x10 (hexadecimal) = 16 (decimal) and its name is "home".

That map file will contain the three things required in importing a VG: the VGID, and the names and numbers of the LVs in the VG.

If /dev/vg04/home is the only thing missing from the map file, we know the device number and the name from our examination of the device node... and the VGID does not normally change after VG creation anyway. We could make a copy of the map file, very carefully edit it to add the information of the "missing" LV, then export and re-import the VG: if the LV is actually present and intact on the disks and just missed in the import procedure (because somehow a wrong map file was used), and nobody has been extending/creating any LVs in this VG before the problem was noticed, that might be a possible way to fix it..

[Vinod Udapudi]

Yes . The VG is currently active.

You are right. I dont know how come /home is not identified by OS. Even in SAM I cant see any logical volume information but can see under file system without any infrmation. SAM shows as ? for /home.

The device file exists but not matching time stamp with ther device files.

Luckily I had backup from Data Protector. So I removed rhome and home with rm -rf. CReated a new logical volume and then new file system followed by new /home.

Restored backup from DP and reboted the server. Then everything looks fine.

but without this I dont know how can we recover. As we have same problem on other server also which we restoted from Ignite.

I will post the results.

Thanks again

Vinod

[Vinod Udapudi]

As I said we have same problem on other machine too which is restored from Ignite.

Attached is the text file with all information.

Please suggest me the way to fix this.

Thanks in advance

Vinod