topic virtual disk in Operating System - HP-UX

virtual disk

Flavio Remo Rossi — Mon, 04 Oct 2004 10:32:17 GMT

Hi all,
I have an EVA5000 attached to un rp5470 with HP-UX1.11. I extended the vitual disk on EVA from 40 to 80 Gb. On HP-UX I see 40Gb. How can I update the information into HP-UX ?
Thanks

Re: virtual disk

A. Clay Stephenson — Mon, 04 Oct 2004 10:41:54 GMT

The disk's (physical or virtual) size is recorded when the volume is added to a volume group. You will either need to backup and restore after recreating the VG OR you can reduce the virtual disk back to its original size (if that operation preserves data) and then use the space to create another disk and add that disk to the same volume group. You can then extend LVOL's and filesystems. LVM does not expect the size of disks to change "on the fly".

Re: virtual disk

RAC_1 — Mon, 04 Oct 2004 10:42:43 GMT

What commands you used?? Did you do extendfs??

Anil

Re: virtual disk

Uwe Zessin — Mon, 04 Oct 2004 13:02:25 GMT

You cannot shrink the size of a virtual disk on the EVA. The only way is to delete it and re-create with a smaller size.

This is a destructive operation!

The old data is gone, because the EVA does not present unwritten data. If you read a block that was never written the EVA does not go to the disk - it 'invents' data.

On some operating systems (and users of Secure Path) it will also appear as a new disk, because the EVA assigns a new LUN WWN. You can save the old one and re-assign it to the new virtual disk as long as it is not presented to a host.

Re: virtual disk

Tim D Fulford — Mon, 04 Oct 2004 15:15:19 GMT

Hi

There is a possible way of doing this IF you are lucky. I think I saw A. Clay propose it some time ago & it is devilishly cleaver & devious...

The basic idea is to trick LVM into re-creating its meta-data with the right sized disk whilst maintaining the Lvols.

0 - backup EVERYTHING ... just in case ..
1 - vgchange -a n vgxx
2 - ll /dev/vgxx/group # note minor number for step 8
3 - tar cf /dev/vgxx.tar /dev/vgxx
4 - vgcfgbackup vgxx # JUST in case #
5 - vgexport -m /tmp/vgxx.map vgxx
6 - pvcreate -f /dev/rdsk/cXtYdZ
7 - mkdir /dev/vgxx
8 - mknod /dev/vgxx/group c 64 0x00000
9 - vgcreate -p 20480 vgxx /dev/dsk/cXtYdZ
*** step 9 must complete sucessfully ***
10 - tar xf /dev/vgxx.tar

And now you have the VG with an 80GB vDisk... I've not tested it yet, so you might want to give it a whirl on a testbed... if step 9 does not work it is probably becasue -p 20480 is too large, I know 20000 DOES work because I use that value regularly..

Good luck, Tim

Re: virtual disk

Flavio Remo Rossi — Tue, 05 Oct 2004 02:59:47 GMT

Hi all,
thanks to all your answers were helpfull and clarifying for me, now i'm going to assign points (I don't forget to do ) but I have another question, What do you think about the idea below ?
Someone tell me : If you use VxFS,LVM (as Volume Manager) and you can use FSADM , you can do the following :
1) BACKUP DATA - to do in any case !
2) lvdisplay -v - to check the Hwpath
3) lvmextend -L "size inMb" \
/dev/vgname/volumename /dev/disk/HWpath
4) fsadm -Fvxfs -b "size inMb" /mpuntpoint

Where "size inMb" is the differences between the original dimension and the new dimension.
What do you (all) think about this ? Is it a good idea? Any idea,suggest will be appreciate
Thanks to all

Re: virtual disk

Sunil Sharma_1 — Tue, 05 Oct 2004 03:15:56 GMT

Your solution will not work in LVM metadata configuration disk is configured as 40 GB and there is no free space to extend volume.

lvextend will fail.

Sunil

Re: virtual disk

Robert-Jan Goossens — Tue, 05 Oct 2004 04:17:12 GMT

Hi,

As Sunil just said this will not work, you can check it yourself.

# pvdisplay /dev/dsk/cxtydz

PE Size (Mbytes) X Total PE = 40 GB

The "disk" has to be recreated as an 80 GB disk.

Regards,
Robert-Jan

Re: virtual disk

John Jimenez — Tue, 05 Oct 2004 13:57:45 GMT

I have an RP7410 which does not have the capabilities of expanding a LUN. We were looking into the EVA. I heard that there was a bug and the the operating system was unable see when the eva was expanded. This was 60 days ago... I heard HP UX 11.11 was working on the problem.... For now you might need to back up your data, remove the logical volume and volume group. Delete the LUN, recreate the LUN, Volume Group, And logical Volume, and restore...

Re: virtual disk

John Jimenez — Tue, 05 Oct 2004 13:59:18 GMT

I have a VA7410 Disk array...

Re: virtual disk

Hoang Chi Cong_1 — Tue, 05 Oct 2004 21:00:50 GMT

Hi man.
For the second question:
If you have Online JFS you can do these command. That means you can extend a logical volume withow "unmount"
Just remember: The size in command:
lvextend -L size /dev/vgx/lvxx
has the same size in this command:
fsadm -F vxfs -b size /mount point.

(Hm....you must be carefull: the right command is: lvextend, not: lvmextend!!!)

Hope this hepls.

Regard,

Jim