topic Re: The amazing dissapearing Logical volume in Operating System - HP-UX

The amazing dissapearing Logical volume

u856100 — Fri, 08 Mar 2002 08:39:05 GMT

Guys,

I am currently trying to uncover the mystery of three logical volumes that are missing from my system. Sam acknowledges that they are there, but cannot see the mount points. My fstab does not indicate their existence, and there are no missing peripherals from the setup. It all seems a bit weird?

The volume group consists of four 2gig disks, 2 of which have Oracle installed, spread over two logical volumes.

I was curious as to whether there is some sort of history log that I can look in to check of their existence.

thanks for any suggestions whatsoever!

John

Re: The amazing dissapearing Logical volume

Thierry Poels_1 — Fri, 08 Mar 2002 08:43:17 GMT

Hi,

is it possible this are raw volumes used for Oracle data??
Oracle can use raw devices instead of cooked filesystems (with ordinary directories and files) for high performance. In this case you will not find any references in /etc/fstab. Check with your DBA.

regards,
Thierry.

Re: The amazing dissapearing Logical volume

Rainer von Bongartz — Fri, 08 Mar 2002 08:47:48 GMT

Looks like you got raw volumes therer with no file system on it.

You wont't seee theese volumes with tools that look for file systems.

Try vgdisplay -v instead

Regards
rainer

Re: The amazing dissapearing Logical volume

Volker Borowski — Fri, 08 Mar 2002 09:04:03 GMT

Hi,

switch to oracle user and do

svrmgrl
connect internal
select * from dba_data_files;
select * from v$datafile;
select * from v$controlfile;
select * from v$logfile;

Check out if the names listed refer to your raw logical volumes or to links that point to these volumes. If yes, Oracle is using these volumes directly, if not, they might have been created and even mounted, but not enterd into the fstab-file.

Volker

Re: The amazing dissapearing Logical volume

u856100 — Fri, 08 Mar 2002 09:04:33 GMT

Hi Gents,

thanks for your suggestions.
There are no raw file systems used by Oracle and I can see the allocated Logical volume groups i.e. :

in sam 'Disks and File Systems'

Name MB available PV's LV's
--------------------------------------
vg00 164 of 2044 1 8
vg01 0 of 8128 4 5

and

#pvdisplay -v vg01 produces :

Volume groups --

Cur LV 5

Re: The amazing dissapearing Logical volume

Rainer von Bongartz — Fri, 08 Mar 2002 09:18:41 GMT

what's the output of

vgdisplay -v vg00
vgdisplay -v vg01

Regards
Rainer

Re: The amazing dissapearing Logical volume

u856100 — Fri, 08 Mar 2002 09:34:07 GMT

I have just checked the tables mentioned above for mount points of the dbf's ctl's etc.

These are all fine and belong to a visible volume group.

I am pretty sure this is not an Oracle problem but something simpler regarding system setup.

The only thing that has happened recently is a power cut where my machine was killed (only a workstation and hash unit so no UPS). I have rebooted since then, about 4 times, but still no lost LV's

hmmmm

Re: The amazing dissapearing Logical volume

u856100 — Fri, 08 Mar 2002 09:35:23 GMT

Sorry, forgot to mention that vg00 is fine and is only recording the standard 8 LV's

cheers

John

Re: The amazing dissapearing Logical volume

Kenny Chau — Fri, 08 Mar 2002 09:35:59 GMT

First, you can do an ioscan on the disk:

# ioscan -fnC disk

Check that all the disk are there and check the device file, ie. /dev/dsk/cXtXdX and /dev/rdsk/cXtXdX

If they are all there, do an vgdisplay

# vgdisplay -v /dev/vg00
# vgdisplay -v /dev/vg01

Check that the how many disks are in the VG and check how many LVs are in 1 VG. Calculate the PEs from the output to see if it matched.

Try to mount the missing LVs to a temp mount point to see if you can mount the LVs.

Have you reboot your server before? If you had reboot your server and did not add the FS in the fstab, it will not mount it after reboot.

Hope this helps.
Kenny.

Re: The amazing dissapearing Logical volume

Carlos Fernandez Riera — Fri, 08 Mar 2002 09:46:04 GMT

1- first thing i do is try to mount them:

mount /dev/vgxx/lvolmissing1 /tmp_mnt

Try with diferent options too:

mount -F HFS /dev/vgxx/lvolmissing1 /tmp_mnt

If it can be mounted then , just see what files contain and maybe you can known what s that.

If you cannot mount go to step 2:

2- dd if=/dev/vgxx/rlvolxx of=/tmp/test1 bs=1024k count=1

strings /tmp/test1 | head -10

If it was a oracle datafile you should see:

Z[\]

followed by a ORACLE_SID.

HTH

Re: The amazing dissapearing Logical volume

Bill McNAMARA_1 — Fri, 08 Mar 2002 11:10:17 GMT

once you've got everything mounted the way you want:

mount -p > /etc/fstab

Later,
Bill

Re: The amazing dissapearing Logical volume

u856100 — Fri, 08 Mar 2002 14:04:52 GMT

Ah,

Apologies to the guys who mentioned it was an oracle related issue.

After interrogating the VG holding Oracle, I can see that the application has been (rather strangely) striped across three disks. I assume that the missing LV's have been created for something like swap.

Why it has striped the application data rather than the oradata, I have no idea (my first install, not knowing a great deal about Oracle architecture).

Anyway, I will look to tidy the structure.

Thanks for everyones help!
Can I re-allocate points to the Oracle related answers? please pose an answer back to this thread and I will assign the surplus!

cheers

John