Maximum Physical Volumes

[Warren griggs]

Hi All,

I had a problem last night moving some disks off of and exsisting jni card onto a hp fibre card, when I booted with the disks connected to the new card it did not show all of the disks. I didn't pvremove the old disks before I done this, I wanted to just add the new disks and be able to roll back if I needed to. The final disk number is 20 (from an ioscan -fnC disk output).

What I wanted to know is, is there a kernel setting for maximum pv's?

If so what is the parameter I need to change?

Thanks,
Colin.

[Robert-Jan Goossens]

Hi Colin,

Not a kernel setting but a volumegroup setting, look at the output from vgdisplay -v /dev/vgxx , there is a max pv setting, default it is 16. You have to recreate the volume group to increase this number.

Hope it helps,

Robert-Jan.

[Warren griggs]

Robert,

That I understand, but surely that wouldn't effect the ioscan output would it?

I'm thinking maybe that there is a problem on the 3rd party disks?

Thanks,
Colin.

[Warren griggs]

I think I have figured out what this could be.

Does anybody know how many devices the

"HP Tachyon XL2 Fibre Channel Mass Storage Adapter"

can support?

The old jni card that they were connected to can support upto 16 devices and in the ioscan it seems only to have 0 - 7 for the new card.

Thanks,
Colin.

[Robert-Jan Goossens]

Hi Colin,

Yes you are right, ioscan should sea the devices.

You could check if you have the latest driver and patches for the Tachyon loaded, take a look at next links.

http://www.software.hp.com/portal/swdepot/displayInstallInfo.do?productNumber=A6795A

http://www5.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000065680512

Robert-Jan.

[Mark van Hassel]

Colin,

Don't worry about the LUN limitation. The card can support way more than 16 luns. Also, these docs might be interesting for you :
http://docs.hp.com/hpux/onlinedocs/netcom/maxlun-whitepaper-v1.0.pdf
http://docs.hp.com/hpux/pdf/J2635-90014.pdf

HtH,

Mark

[John Meissner]

depending on your PE size you will be linited to the max ammount of physical volumes

a PE size of 4 will only allow aprox 116 (not sure of the EXACT number - but it's close) physical volumes.... whild a PE size of 8 or 12 will allow for more devices. Change your PE size when making your volume group and you will be able to use more disks

[Steven E. Protter]

I have Tachyon Fiber adapters attached to a non-HP disk array. Xiotech Magnitude.

I most certainly do have a LUN limit of 8 because I'm using a relatively unknown array. I've been waiting for a driver upgrade to raise that limit for two years. To know if you face this issue, you need to checki with your disk array maker and then HP for the LUN limit on the driver.

You should be able to increase the number of disks allowed in the volume group with the commands above.

Just note, if the total disk space you are attaching is large you may need to rebuild the volume group.

vgcreate -e allows you to set the number of "clusters(I think)" in the volume group. The default is also lower than practical. Disks got bigger very fast, what can I say.

SEP