LVM and VxVM

Using all disk space after mirroring

 
BigMax
Advisor

Using all disk space after mirroring

So i have HP-ux on parisc server.
I had a two 73 GB hard disks wihout a mirror. Than i installed MirrorDisk/UX (licenced copy) and created a root mirror according to HP documents and recomendations. It worked fine. Than i got two 300Gb hard disks from HP. So i have removed mirror using also that HP document.
After that i changed one of the 73Gb disks to 300 and created a mirror, then i removed the mirror leaving 300Gb as a master. Then Installed one more 300GB disk instead of the las 73gb one and rebuild the mirror once again. So now it works fine - no problems but i want to use all th 300 gbs.
So i have vg00 and SAM says the following:
Disk megabytes 286102 (300Gb - is correct) and usable megabytes 70102 (73gb - also correct).
A have 9 LVol's in this Vg.

So the thing is that i cannot create new lvol,
and also i cannot add new VG.

So does anyone have idea how no use all the 300Gbs?
It does not metter to me - to add a new lvol, vg or extend one of existing.

Thanks in advance!
The document is in attach. see page 22 for root mirror.
18 REPLIES 18
Victor BERRIDGE
Honored Contributor

Re: Using all disk space after mirroring

Greetings my friend,

What happened is you used the default vg parameters with your system, and there is not alternative but to reinstall... that is, all the definition of the volume group is done once at the creation time (max pvs max extents etc...) you have a way of getting yourself out by using an ignite tape and using it to reinstall on the 300GB disks, it will then set new values according to the disk size


All the best
Victor
Matti_Kurkela
Honored Contributor

Re: Using all disk space after mirroring

This might be one of the top 5 problems people are having with HP-UX LVM.

There are some parameters that are set when a VG is created and cannot easily be changed afterwards. These are:
- the max number of PVs in VG (Max PV)
- the max number of physical extents per PV (Max PE)
- the size of physical extents in VG (PE size)

If the Max PE value is not specified when creating the volume group, it will be automatically set to 1016 or the smallest number necessary to cover the (largest) PV in the VG _at the time of creation_.

The default PE size is 4 megabytes. So, if the system disk is larger than about 4 gigabytes (=always on modern disks), the vg00 will always be auto-sized so that it cannot later accept bigger PVs than used at the creation time.

The only way to fix this problem is to destroy the VG an re-create it with a larger MaxPE value - and if the VG is vg00, this usually means creating an Ignite tape (make_tape_recovery -x inc_entire=vg00) and using it to recreate the system with a larger vg00.

At the moment, I don't remember whether you can override the autodetected parameters of vg00 when installing HP-UX. (It might be that you can easily change PE size, but not MaxPE.) If you suspect you'll need to move vg00 to larger disks, you should make sure the vg00 is created with suitable parameters at HP-UX installation time.

This is also why it is generally not recommended to put data volumes in vg00: the data will usually grow beyond original estimates, and re-creating a separate data VG is much more convenient than re-Igniting the entire system when you hit LVM limits.
MK
BigMax
Advisor

Re: Using all disk space after mirroring

Thanks guys, can you please check the attached screenshoot? Maybe it will tell you smthing abount the param of my vg00.
Victor BERRIDGE
Honored Contributor

Re: Using all disk space after mirroring

Yes its your maxPE that limits your total size... And as said it is set at volume group creation...

But now 73GB is plenty big enough for vg00, why not use them as for system purpose only and start of a new group vg01 in mirror using your 300GB disks?

All the best
Victor
BigMax
Advisor

Re: Using all disk space after mirroring

Maybe it's a solution - to leave one 73 gb for system and two 300gb for data but the task is to use onlu 2 disks and mirror both system and data.
BigMax
Advisor

Re: Using all disk space after mirroring

So guys... is it really no way to use all the disk without reinstalling? Maybe some magic....
Victor BERRIDGE
Honored Contributor

Re: Using all disk space after mirroring

As I said,
Use the 2 73GB for vg00, and use the 2 300GB for vg01 and mirror the 2 vgs!
You have then the best of all
BigMax
Advisor

Re: Using all disk space after mirroring

Ha! This is not acceptable because my server has only 3 ports for HDD's as i told i have 3440 parisc.
Robert-Jan Goossens_1
Honored Contributor

Re: Using all disk space after mirroring

two options.

A If you have a tape drive attached to this system or you have an ignite server in your subnet, create an make_tape_recovery/make_net_recovery and recover your system to the larger disks.

B If you are on 11.11, call the HP Response Centre and request the unsupported utility called vgmodify.

Best regards,
Robert-Jan