Disks missing from /etc/lvmtab

[WSS]

Hi All,

I have some disks missing from /etc/lvmtab and need to get them back in there via vgextend etc, but wanted your advice on the best way to do it - This is the output from strings /etc/lvmtab -

root@ugos388# strings /etc/lvmtab
/dev/vg00
/dev/dsk/c2t1d0s2
/dev/dsk/c3t0d0s2
/dev/vgapp
/dev/dsk/c4t0d1
/dev/dsk/c8t0d1
/dev/vgclwss
/dev/dsk/c4t0d3
/dev/dsk/c4t0d4
/dev/dsk/c4t0d5
/dev/dsk/c4t0d6
/dev/vgclord
/dev/dsk/c4t0d7
/dev/dsk/c8t0d7
root@ugos388#

The volume group /dev/vgclwss should have the alternate disks in the lvmtab, which should be /dev/dsk/c8 ...

Can someone tell me how to identify the 4 disks that need to be put into the /etc/lvmtab file and the syntax to do that.

Thanks alot
Trev

[Ninad_1]

Hi,

When you say the alternate disks are missing - do you mean the disks shown in vgdisplay -v output as Alternate Link ?
Then they will not show in the lvmtab as they are just differnt path to same disk.
Regards,
Ninad

[James R. Ferguson]

Hi Trev:

First, one does not edit '/etc/lvmtab'. It is a binary file maintained by 'vgscan', 'vgextend', 'vgreduce', 'vgimport' and 'vgexport'.

If you want to add alternate links (pvlinks) to the volume group "/dev/vgclwss", use 'vgextend':

# vgextend /dev/vgclwss /dev/dsk/cXtYdZ

Regards!

...JRF...

[HGN]

Hi

The alternate disks will not show up on the /etc/lvmtab file.

Rgds

HGN

[Victor Fridyev · Accepted solution]

Hi,

AFAIK, the simplest way to see alternate pth disks in /etc/lvmtab is to add the disks to volume group.

If the alternate path is dev/dsk/c8t0 , then the needed command is
vgextend /dev/vgclwss dev/dsk/c8t0d3 /dev/dsk/c8t0d4 /dev/dsk/c8t0d5 /dev/dsk/c8t0d6

HTH

[Josiah Henline]

Both the primary link and the alternate link should be included in the VG and the lvmtab.

If you are not sure and are not on a clustered system, you could do the following steps:

mv /etc/lvmtab /etc/lvmtab.bak
vgscan -v # This will take awhile to run
strings /etc/lvmtab
#You should see the pvlinks in the vgdisplay and the lvmtab
vgchange -a y /dev/vgclwss
vgdisplay -v /dev/vgclwss

If you have a way to find out which devices are suppose to be the alternate links, you can simply vgextend them into the VG.

vgextend /dev/vgclwss /dev/dsk/cXtXdX

[Ninad_1]

WSS,

Sorry - the disks should be visible in /etc/lvmtab.
And you can add those disks using vgextend vgname disk1 disk2 ..
No points for my posts please.

Regards,
Ninad

[Darrel Louis]

Hi,

Before using vgextend check with pvdisplay -v /dev/dsk/c8t?d? if the disk belongs to a Volume Group.

Darrel

[Sivakumar TS]

Hi,

to rescan and recreate the /etc/lvmtab,

do move the existing lvmtab and rin #vgscan

Regards,

Siva.

[Enrico P.]

Hi,
if the commmand

vgdisplay -v /dev/vgclwss

not shows the Alternate Link disk, Es:

PV Name /dev/dsk/c6t3d4
PV Name /dev/dsk/c4t4d3 Alternate Link

You need to add them:

vgextend /dev/vgclwss /dev/dsk/c8t0d3 /dev/dsk/c8t0d4 /dev/dsk/c8t0d5 /dev/dsk/c8t0d6

and

strings /etc/lvmtab should to show them

If the vgdisplay show them and lvmtan not show them, you need to run the vgscan command:

mv /etc/lvmtab /etc/lvmtab.old
vgscan -a -v -p (preview)
then
vgscan -a -v

Enrico

[Arunkumar.B]

HI,

Automatically the links will not disappear.Pls check the root cause of that...
For bringing the links its not a matter.u can issue vgextend..Is there any errors in the syslog regarding the missing links..

Cheers
Arunkumar.B

[Sandman!]

Could you post the output of ioscan...

# ioscan -fnC disk

Were the alternate links present in /etc/lvmtab? If that's the case then the easiest way to recover them is by doing a vgchange i.e.

# vgchange -a y vgclwss

See vgchange(1M) for details.

[rariasn]

Hi Trev,

Verify than diskc c7t0d[3-6], are presents in "vgclwss":

# vgdisplay -v vgclwss

--> Act PV ?
--> Physical volumes ---
PV Names ?

rgs,

ran

[BPatrick]

Trev,
Copy the lvmtab to some safe location and then do a vgscan
vgscan -a -v
this will recreate the lvmtab file

[Sp4admin]

vgdipslay -v vgXX should show the pv links. then vgextend dev/vgXX /dev/dsk/c#t#d#. do a strings on /etc/lvmtab and you should the the pv link.

[Mridul Shrivastava]

If a storage is connected to the server then its not recommended to execute vgscan -a -v as it will add device files to other vgs also and u may get confused so better way to add alternate disk is to do it manually. you know the device file names so execute vgextend command for each pv that will be added as alternate link.
If you want to do load sharing and change the prmiary link for different pvs then after extending it to alternate link execute vgreduce command on primarly link so the next link will become primary link. Later on add other link also so that will become alternate. This is helpful while planning for load sharing..

[WSS]

Thanks for all responses guys, I have vgextend'ed the volume group and the disks are now seen in the strings /etc/lvmtab. Sorry it's taken a while to get back, but been a little hectic here.

For those that suggested doing a vgscan -a -v I didn't do this, as this can cause more problems than is already there!! You need to be VERY careful when running vgscan it's a very powerful command

James - I never said I was going to 'edit' the /etc/lvmtab file, I know you can't do that, I said I was going to use vgextend to add the disks

All people that suggested searching for the correct disks and using vgextend to add them I have assigned points.

In Summary -

I did this (for each disk that should be in /dev/vgclwss)

# ioscan -fnC disk | grep c8t0d3 (d4, d5 & d6)
# vgextend /dev/vgclwss /dev/dsk/c8t0d3 (d4, d5 & d6)

And this is now my strings /etc/lvmtab output -

# strings /etc/lvmtab
/dev/vg00
/dev/dsk/c2t1d0s2
/dev/dsk/c3t0d0s2
/dev/vgapp
/dev/dsk/c4t0d1
/dev/dsk/c8t0d1
/dev/vgclwss
/dev/dsk/c4t0d3
/dev/dsk/c4t0d4
/dev/dsk/c4t0d5
/dev/dsk/c4t0d6
/dev/dsk/c8t0d3
/dev/dsk/c8t0d4
/dev/dsk/c8t0d5
/dev/dsk/c8t0d6
/dev/vgclord
/dev/dsk/c4t0d7
/dev/dsk/c8t0d7


Thanks all.
Trev