Can we create new VG?

[Gino Castoldi_2]

Hi,

Background:
L2000, HP-UX 11.0, SureStore E 12H AutoRAID
Disk Array with six 18GB drives.
(There are two L2000's that run MC/SG that share the AutoRAID disk array).

(vg00 = boot disk only, vg01 = AutoRAID disk array).

We have extra disk space on vg01. Can we allocate that disk space to a new volume group or just to the existing volume group (vg01)?
Note: The AutoRAID has allocated all disk space.

(10 points to any good answer).
Thank you Gino.

[James R. Ferguson · Accepted solution]

Hi Gino:

No, a physical disk belongs to one and only one volume group.

Regards!

...JRF...

[Patrick Wallek]

Has the LUN, or LUNS, that have the free disk space been added to another VG? If not, then you can create another VG using that LUN.

You could also vgextend an existing VG to use that LUN as well.

Either way will work. Extending a current VG usually gives you a bit more flexibility since you can then use that disk space, if needed, with LVs that are currently configured.

[Domenico_5]

ciao gino

Depends,is vg01 used in Service Guard??

If not, you can create a new local volume and not a volume group.

bye

[Thierry Poels_1]

Hi,

a Volume Group is a group of Volumes, either physical disks or LUNs (Logical Units, part of a disk array).
So if you have no more free disks or LUNs it's quite difficult to create a new VG.

regards,
Thierry.

[Darrell Allen]

Hi Gino,

A disk / lun can only be a member of one VG. Extra disk space in vg01 can not be allocated to another vg unless you can free all physical extents (PE) from a single disk. Then you could vgreduce that disk from vg01 and vgextend another VG.

Darrell

[Vincent Farrugia]

Hello,

If I understand you correctly, you have vg01 taking up the space of all the AutoRAID array, but you want to use some empty space on this vg to create another vg.

You can do that "on the fly" in theory. But, since AutoRAID does not write contiguously, you would be risking data loss if you reduce the size of your vg on the fly. I would suggest taking a whole backup or two of the vg01, recreate the vg with the size you want, then restore the data afresh.

Now, doing this may pose some performance problems on your AutoRAID, though. The best strategy is to keep 50% of the disk space unused, so that all data in the AutoRAID will be in Raid 0/1. If you are making another vg and fill it in, more data will be stored and it will pose some performance problems.

HTH,
Vince

[Thomas Schler_1]

Volume groups are defined by a set of individual physical volumes (disks) or a set of individual physical volume groups.

If you already use all the six disks of the array to set up volume group vg01, there's no chance to define an additional volume group since there are no more disks available. If you reduce (vgreduce) volume group vg01 to get (unused) disks freed, you can use these disks to define a third volume group (beside vg00 and vg01).

If you are not able to vgreduce vg01, i.e. all the disks are at least partially
used, you have two possibilities:

1. Just create new logical volumes within vg01. These logical volumes must be part of the filesystems defined within MC/SG.

2. Re-arrange all the logical volumes on vg01 to get disks that are completely not occuppied by data, so that you are able to vgreduce vg01 at the end. This procedure is, of course, very time-consuming and, maybe, you have to stop all or a subset of software packages defined in MC/SG, temporarely.

[Magdi KAMAL]

Hi Gino,

If one disk ( Physical Volume ) is already attributed to a Volume Groupe, you can not reattribute it again to a different one.

But, you still can do the following :

When you create your LUNs on the AutoRaid, so that one of it will be attributed to vg00.

If you had already created your LUNs and had attributed all of them to the vg01, then you need to perform a backup and to reconfigure the LUNs again to pring out whatever LUNs out from your vg01 and then attribute them to the vg00. And this attribution will be outside the MC Service Guard and fixed for specific server ( Not package ) !

Magdi

[Gino Castoldi_2]

Hi Everyone,

Thank you for all your answers.

Basically my only option is to vgextend the volume group (vg01). I can not re-configure the AutoRAID.

Thank you again Gino.