topic Re: cannot see unused disks... in Operating System - HP-UX

cannot see unused disks...

Bing Wong — Mon, 06 Feb 2006 12:12:04 GMT

I am still new to HP-UX world. I have an issue that I need help. I requested storage group to add 40GB to a storage group on EMC that is attached to HP-UX. They created a new LUN and added to an existing storge group. Original size of the sotrage group was 200GB and now it is 240GB. But I don't see the new LUN after I ran "ioscan -fnC disk".
VGDISPLAY--------------------------------
VG Name /dev/vgemc
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 6
Open LV 6
Max PV 16
Cur PV 1
Act PV 1
Max PE per PV 25599
VGDA 2
PE Size (Mbytes) 8
Total PE 25596
Alloc PE 25386
Free PE 210
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

More Questions:
(1) The MAX PE per PV is 25599 and Total PE is 25596. Does it mean that vgemc cannot be expanded any more?
(2) Can 2 storage groups of EMC be attached to one physical HP-UX server?

I really appreciate your help.

Re: cannot see unused disks...

Steven E. Protter — Mon, 06 Feb 2006 12:28:10 GMT

Shalom,

For non-hp disk arrays it is usually necessary to reboot the system so that disk assigned to the WWN, world wide name of a fiber channel adapter can be seen.

You may try:
insf -C disk

But likely you will need to boot.

1) Yes, you are full up on extents and need to set up a new vg for the new disk and/or recreate the volume group with the -p parameter. This will spread your useful PE's physical extents over fewer disks. Make sure you leave room for some extra luns.

2) Yes, directly, one to each fiber card or even more via a Fabric/Fiber optic network, known as a SAN, Storage Area Network.

SEP

Re: cannot see unused disks...

John Dvorchak — Mon, 06 Feb 2006 12:36:39 GMT

Before I reboot I would try ioscan -Cdisk to get the same effect as a reboot. At reboot it will do the ioscan and pick up the new hardware, if the box is already running you can just run ioscan and it will find all new hardware. Then use Stevens suggestion of insf -e to build the /dev/dsk and /dev/rdsk files for you.

Re: cannot see unused disks...

Bing Wong — Mon, 06 Feb 2006 13:45:40 GMT

Thank you.

Is there a way to increase the MAX PE per PV parameter or it is at max already?

Max PE per PV 25599

I will check on our Fabric/Fiber Optic Network/SAN.

Re: cannot see unused disks...

DCE — Mon, 06 Feb 2006 13:49:51 GMT

The max pe is hard coded when the volume group is initially created. The only way to make it larger is to destroy the vg and recreate it with a larger max pe. This will, of course, destroy any existing data, so make sure you have good backups!

Re: cannot see unused disks...

Steven E. Protter — Mon, 06 Feb 2006 13:54:16 GMT

Sorry, that is set at Volume group creation time.

I talked to an engineer about it in 2002 and the reasoning behind this seemed to make sense.

Thats all I recall from that conversation.

SEP

Re: cannot see unused disks...

David Bellamy — Mon, 06 Feb 2006 14:17:57 GMT

Bing all you have to do to see the new disk is
1. ioscan
2. insf -e -C disk
3. ioscan -funC disk

after you do these steps disk will show up

Re: cannot see unused disks...

Bing Wong — Mon, 06 Feb 2006 17:34:17 GMT

I am going to apply cummulative patch for SAM. So I need to backup the system before doing so. What's the best way to back up entire OS and when to make sure all files are backed up.

Thank you for your help.

Re: cannot see unused disks...

Nguyen Anh Tien — Mon, 06 Feb 2006 21:35:30 GMT

Hi BingWong
To backup entire OS (not include your data) you should use ignite -backup.
check ignite installed by:
#swlist |grep -i ignite
you can refer more at:
http://www2.itrc.hp.com/service/james/search.do?searchtext=ignite+backup+software&submit.x=0&submit.y=0&hpl=1&todo=search&searchcriteria=allwords&from=forums&searchcategory=ALL&rn=25&presort=rank&source=7000&esc=us.support.itrc.hp.com&wpa=forums1.itrc.hp.com%3A80&origin=0&chkServStor=on

Re: cannot see unused disks...

Devender Khatana — Tue, 07 Feb 2006 01:35:32 GMT

Hi,

There should not be any problem in adding the new LUN to your vgemc as your vgemc has only one PV so far and will allow 15 more in it. Also the Max_PE_PER_PV and PE_size is set to allow one single disk/LUN of 200GB.

It appears that instead of creating a new LUN they have extended the existing LUN to become of 240GB. Is it ?

If yes even if your MAX_PE_PER_PV is set properly to allow the new size, then also you can not change VG config as HPUx will not allow you to do that. You can not do a PV extention in HPUx.

An alternative will be to ask your storage people to create a new LUN and assign it to your host. Any LUN of sizes upto 200 GB will be enough for you to be added to this VG.

HTH,
Devender

Re: cannot see unused disks...

Yogeeraj_1 — Tue, 07 Feb 2006 01:43:19 GMT

hi,

for the backup see also:

man make_recovery

hope this helps too!

kind regards
yogeeraj

Re: cannot see unused disks...

Bing Wong — Tue, 07 Feb 2006 15:37:46 GMT

Hi Devender,
No, they created a new LUN(40GB) and assigned it to the existing storage group(200GB) on EMC. But I cannot see the 40GB unused disk space after did all the ioscan...That's why HP told me to apply patches to SAM and hopefully SAM will be able to see them. Will let everyone know later.

I understand now that vgemc can have up to 16 PV and each PV max size is 200GB. That's good enough for me!

Thank you.

Re: cannot see unused disks...

Bing Wong — Tue, 07 Feb 2006 15:39:48 GMT

Yes, I will take Ignite backup first.

Thank you.

Re: cannot see unused disks...

Bing Wong — Wed, 08 Feb 2006 13:56:00 GMT

Hi,
What's the command to modify the parameter "PE Size (Mbytes)" of a VG? Can it be modified dynamically - reboot required?

Thanks.
Bing

Re: cannot see unused disks...

Darrel Louis — Wed, 08 Feb 2006 17:06:41 GMT

Bing,

PE-size can't be changed after the Volume Group has been created.
You need to specify the PE-size during the vgcreate command.
Check the man page : man vgcreate

vgcreate -s

Darrel