How to determine what disks are not assigned to any volume group

[Becke]

Hi Guys,

would anyone be able to tell me what is the command to find out what disks are not assigned to any of the volume groups in the system and are available.

And what is the command to add a disk and extend the root volume group. I'm learning hp at the moment and my expertise is in AIX.

Please advise,

Cheers,
Raf

[Steven E. Protter · Accepted solution]

Part 1.

Two commands and eyballs.

strings /etc/lvmtab

# lists the contents of a volume group.

ioscan -fnC disk

Any disk listed on the ioscan and not the strins command is not assigned.

There are other ways of figuring it out as well. sam can be helpful.

Lts say we identified a disk /dev/dsk/c2t2d0 that is not in a volume group and you want to extend vg02 ti include it.

vgextend /dev/vg02 /dev/dsk/c2t2d0

SEP

[Sudeesh]

Hello,

ioscan -fnC disk -> will give you all the disks configured in the system.

strings /etc/lvmtab -> will give all the disks added to vg.

Match these out puts and you can identify the disks that are not configured into any of the vg.

You can add a disk to root vg (vg00) with the normal vgextend command.

vgextend /dev/vg00 /dev/dsk/cxtydz

But if you are planning to extend /,swap or /stand logical volumes inside root vg... it is not possible even with Online JFS because these lvols have contigious allocation policy.

Hope this helps

Sudeesh

[Naveej.K.A]

Hi,

Before adding any disk to a volume group, you have to make the disk usable by LVM.

pvcreate -f /dev/rdsk/c2t2d0 # -f for forceful creation and don't forget to use the raw device file to initialize the disk for LVM

Regards,
--Naveej

[Bharat Katkar]

Hi Raf,
Just to summarize the steps...

1. # strings /etc/lvmtab
Note the Output
2. # ioscan -fnC disk
Note the Output and select all those disks which were not in the output of #1
3. # pvcreate -f
This will create a PV
4. # vgextend vg00

Thereafter you can use lvcreate or lvextend to create new LV's or extend existing LV.
If you are creating new LV then use:
# newfs -F vxfs
and if you have extended LV and want to increase filesystem size then:
# extendfs -F vxfs
That's all.
Hope that helps.
Regards,

[Bill Hassell]

The very easiest way is to ask SAM. Run sam and select Disks and File Systems, then select Volume Groups. Now select Actions -> Create, then choose a dummy name for a new volume group and then Select Disk. SAM will find all disks that do not belong to volume groups defined on this system. You can then cancel out if you wish.

[Stuart Abramson]

All these answers are right. I don't use SAM because on a system with a lot of disks SAM can take forever to respond (it just seems like forever compared to using commands). I wrote a script to do this for me, which I would attach but I don't have it handy. It uses "inq" which is an EMC command.

[Saravanan_15]

Dear Farhan,
You can use the following simple script to find out which are disks not assigned to any VG,

#ioscan -kfnC disk|grep dsk|awk '{print $1}' > /tmp/dsk1
#strings /etc/lvmtab|grep dsk > /tmp/dsk2
#diff /tmp/dsk1 /tmp/dsk2|grep dsk|awk '{print $2}'

good luck...

Regards,
Saravanan M

[Stephen Keane]

Slight caveat, iocsan -Cdisk etc will also list CD-ROM/CD re-writer devices.

[Becke]

Thanks for everyone's response and help, i was away off sick and will try soon, this info would be enough to find out the disks.

Cheers,
Raf

[Geoff Wild]

Also - look at the pvdisplay command....

Rgds...Geoff