maxvg > 256 ?

[Lai Nee Shyang_1]

Hi there,
I've something rather silly to ask. Is there anyway to incrase the maxvg to be more than 256 on HP-UX 11.0.
I've have a V2500 runing HP-UX11.0, connected to a XP512 and XP256. Currently we have 3 groups of VGs in this system, CA and BC (both 80 VGs) and a QA system (63 VGs). But our space are runnning out and we are migration to a XP1024, with CA and BC both 136 VGs. The maxvg doesn't even able to cover 136x2VGs.
Anyone has any creative idea ? I'm really in a fix...

Thanks.

Lai

[twang]

To verify the maxvg:
# sysdef | grep vg

To change:
- creating a new kernel:
# cp /stand/system /stand/system.prev
# cp /stand/vmunix /stand/vmunix.prev
# vi /stand/system

add the following line and save file.

maxvgs 20 .

then,
# mk_kernel -s /stand/system -o /stand/vmunix

Note: backup OS using ignite-ux before any system change.

[Lai Nee Shyang_1]

Hi Twang,

Can this method to increase the maxvg to more than 256 ?? That's the crucial point..

Lai

[twang]

Sorry for my misunderstanding, I don't think that the maxvgs parameter can be increased to 256.
(no point please)

[Lai Nee Shyang_1]

Hi Twang

NO problem, thanks for your attention.

Lai

[RolandH]

Hi twang,

I have a 11i system and I opened sam and looked in the help section of the configurable parameters. The max was 256 there,too. So I don't think you can increase this parameter more than 256.

I think there is no way that you must redesign your XP1024 configuration together with HP.

That will not really help, but this is the only advise I can give you.

Roland

[Lai Nee Shyang_1]

Hi Roland,

I end up in this situation due to a over-look from HP's presales. They sell me a XP1024 without first looking if my V2500 can handle it in the first place. That's why i was hoping if there's any remote chance of changing the Maxvg parameter for more than 256. Now that the XP1024 has rolled in but the server cannot support all the volumes. I can't change the luns size, VG size because it is a CA/BC copy of my production, and changing the production means catrastophic moves (backup / restore, 3-4 days without production, probably I'll out of job then).

Well, just a crazy idea. But thanks Twang and Roland anyway. U ITRC guys r great..

Lai

[RolandH]

Hi Lai Nee,

another idea. Perhaps you are able to use veritas volume manager instead of LVM and you have not the limitation with that. Check it with HP.


Roland

[RolandH · Accepted solution]

Hi Lai,

I have just spoken to a colleague of me and he is certified in VMM and he said the parameter has no affect on VMM.

But the change from LVM to Veritas is a little bit complex. The next problem is you can not have LVM and Veritas at same time.
ie. one part of the 136VG is LVM and one is Veritas. That you stay under the maxvg limit. NO WAY!!! But it is possible to change the LVM structure to Veritas. Think about it together with HP about a migration to veritas. I think HP owe you some.(especially the HP Sales man. Otherwise send him a bullet)

Roland

[RolandH]

Hi Lai (again and again and again),

First of all it is possible to have LVM and Veritas paralell on one system (good news, is'nt it). Second, there is a tool that can convert LVM VG to VMM VG without any loss of data "vxconvert" (VERY VERY GOOD NEWS). But you must be aware of some restrictions in the migration process!! With support from HP and a license for VMM I think you migration will be possible (99,8 %). =;-}}}


I have attached the migration manual.



HTH
ROLAND

[RolandH]

I think the first attachment is corupted!!!

[Patrick Wallek]

How about looking at it a little differently. Do you ABSOLUTELY HAVE to have all of those as separate VGs? Can you combine some of the VGs so that you have fewer VGs with more LVs in each VG? Each LUN on the array does not have to be it's own VG. When you create LVs you can specify the c?t?d? device that it is created on so you could still have 1 LV per LUN if that is your requirement.

By the way, the reason for the limit is in the minor number of each VGs group file. The 0x??0000 number. The ?? is a unique hexadecimal number assigned to each VG. The max for a 2 digit hex number is FF, which to us humans is 255. So you have a range of 00-FF, or 0-255 for a total of 256 possible VGs

[Cheryl Griffin]

Currently 256 is the limit but there is an SR for to have the limit increased, SR #8606128492. I would suggest contacting your local HP Response Center and ask that they raise the priority on this SR. Customer feedback is always taken into consideration when prioritizing SR's/ER's.

[Lai Nee Shyang_1]

Hi Roland,

Thanks. That's great idea abt moving to VNM. I need to check out with the HP folks abt the migration and license $$. I'm only worried whether the CA and BC copy can be move to VNM without moving the production copy. Let me check with them.

Hi Patrick Wallek,

Sad to say, my V2500 hosts 3 copies of LUNs, CA, BC and another QA. All to be expanded to 136 VG (each 108.5 GB). I can change the QA VG sizing, but i can't change the CA and BC VG sizing without changing the master copy, which is my Production copy. And I believe to change it means 3-4 days of down time (current production is 8.4Tb). For that, my bosses may hang me. Beside Roland's suggestion of moving to VNM, the next option is to move the BC copy out and shrink the number of VG on QA. But I have physical constrains as I need to find servers and services from HP to move the BC copy out of the v2500.

Cherly,
Thanks! I didn't know there is such a request going on, I'll check with my HP folks here. But I only worried it may be tie in to some addressing space in HP-UX and it may not be easy to change, or they can only release this change in next ver of HP-UX.

To all u guys, thanks again.


Lai

[RolandH]

Hi Lai,

I'll keep my fingers crossed.
Give us feedback, if you find a solution.

Roland

[Steven_155]

I know it's been addressed, but can you change the maxvgs using command lines instead of editing the system file?

I tried the following:

kmtune -l -q maxvgs
kmtune -s maxvgs=25
kmtune -d


The -u flag won't work since it cannot be dynamically changed.

I figured there must way to do it this way.

[Steven_155]

Oh, try this!

# kmtune -l -q maxvgs
# kmtune -s maxvgs=25
# kmtune -d
# mk_kernel -o /stand/vmunix
# sync
# reboot
# kmtune -l -q maxvgs