Adding a disk to a volume group --- is it an idiot proof process ?

[Andy Hibbert]

Hi,

I have inherited an HP 9000 800/G30 running
HP UX 10.2. I have a 2gb disk that I want to add to a volume group in the system.

How "intelligent" is SAM when adding disks ?
Will it back off if it detects a problem and restore the original configuration ? or will it
continue to the end and break the volume ? I can't afford the down time to re-build from backups.

Thanks

Andy.

[Paul Gold]

Andy

if SAM detects a problem (or the command line option also) it will halt the changes, it will not continue and make any changes so you shouldnt have any worries

Paul Gold
CAST Systems

[Jennifer Chiarelli]

All you should need to do (after a backup of course) is go into sam and expand the volume group. Then you can expand the file system in sam as well.

[Michael Tully · Accepted solution]

Hi Andy,

This is a fairly easy process that can be
done at the command line. Nothing is actually
committed if there is a problem encountered.
This can be done is SAM but can just as easily
be done at the command line.

The disk can be recognised by running an ioscan
on your system.

# ioscan -funC disk
If you cannot recognise the disk you can run a

# diskinfo /dev/rdsk/cXtXdX on any disk. This
will tell you the type and size. Once you know
which disk it is run the following commands to
add to your existing volume group.
# pvcreate /dev/rdsk/cXtXdX
If the disk has been used before you will encounter an error message. If so add the -f
option to pvcreate to force.

# pvcreate -f /dev/rdsk/cXtXdX
# vgextend /dev/yourvg /dev/dsk/cXtXdX

Then you can add more logical volumes or
extend existing ones.

There are many posts on this.

HTH
Michael

[Bill Hassell]

SAM is quite good at paranoia checking. If the disk has been previously used and has a filesystem, it will ask permission to use it anyway. If the disk does not respond to a simple SCSI inquiry, it will not show up as available. SAM will not perform a surface test or extensive diagnostics, but adding a disk to a volume group will not affect the current definitions.

You can do a simple surface check with dd, something like this:

dd if=/dev/rdsk/XXXX of=/dev/null bs=64k

Replace XXXX with the device file name of the new disk. The above technique is also a way to light up the disk when you are trying to identify a physical disk in the midst of several others. If a read error shows up, dd will stop with an error message.

[Shahul]

Hi

I suggest U to use command line for this. Follow these steps

Connect ur new disk and boot the system.
Once U login
#ioscan -fnC disk

Now U can see all the disk's device files which are connected to system.
Find out ur newly connected disk's device file by using its device ID. Here U should be very careful, If U select wrong device file U will end up in problem. Assume U have selected the device file correctly
#pvcreate -f /dev/rdsk/cxtxdx
#vgextend /dev/vgxx /dev/dsk/cxtxdx

For vrifying ur addition use this
#strings /etc/lvmtab

Now ur job is over.

Best of luck

Shahul

[John Bolene]

Sam is a wonderful tool to use for this purpose. It will check the drive to make sure it can read and write it, and then allow you to add it to the volume group.

If it can't read and write it, it will say that it has 0 bytes of space left.

[Naseemuddin Mohammed]

Hi
Andy,
If you use sam or manual method for adding disk to volume group there will be no down time. If you want extend production filesystem then you need to have you backup ready, unless you Online JFS to use fsadm to extend the file system.

Thanks!