topic Re: What is PVG in Operating System - HP-UX

What is PVG

Tommy Yip — Fri, 24 May 2002 03:35:17 GMT

I'm the new user of HPUX, can anyone tell me what is PVG, and what is the different between doing mirror with separate disk and mirror with other PVG.

Re: What is PVG

Printaporn_1 — Fri, 24 May 2002 03:41:10 GMT

Hi,

it is for seperate disks in vg to groups for mirroring benefit , that you can control the LV allocation of PE to the right disks.

Re: What is PVG

S.K. Chan — Fri, 24 May 2002 03:47:32 GMT

In my own way I call it a "dirty" mirror (no PVG) vs a "clean" mirror (with PVG). Imagine you got 4 disks (A,B,C,D) and you're going to setup you VG.
Clean-mirror
============
You would setup the VG by putting A and B in PVG1 & C and D in PVG2 when you create your VG the first time using "-g" option to define the PVG name. Now when you create you LVs and you want to mirror say 1 copy you would want the mirrored copy to reside in a separate PVG instead so that you know your mirrored copies are always in PVG2 for example. This would also help in disaster recovery situation. The "lvcreate" command has "-s g" option that tells it to do a PVG-strict mirror. Going forward extending your existing LVs would just be a straight forward "lvextend" since it was already defined as PVG-strict.
Dirty-mirror
============
You setup the VG in a normal manner. In the creation of your LVs, if you simply say mirror 1 copy and let LVM figure out where to put it's mirrored copy then you may end up in a siuation whereby your mirrored copy can reside anywhere in A,B,C,D even on the disk where the primary copy sits ! Having said that you can actually tell lvextend to put your mirror-copy to a specific disk but then you would have to keep track of the PEs, etc, etc. If PVG is setup this is done automatically.

Re: What is PVG

Tom Geudens — Fri, 24 May 2002 03:51:48 GMT

Hi,
There was a fine discussion about this not so long ago ... where was it again ... ah, found it : http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x437142308663d611abdb0090277a778c,00.html

For more information, just search the forums with keyword 'PVG'.

Hope this helps,
Tom

Re: What is PVG

kish_1 — Fri, 24 May 2002 03:54:06 GMT

Hello,
Go through the document B3936-90065.pdf in docs.hp.com
you will have good knowledge of PVG,LVM and mirroring

Re: What is PVG

steven Burgess_2 — Fri, 24 May 2002 03:57:18 GMT

Hi

Have a look at the attached also

Regards

Steve

Re: What is PVG

Victor_5 — Fri, 24 May 2002 13:50:47 GMT

Take a look this paper, you also can get it from IRTC, no is KBAN00000091. Enjoy!