Re: multipath slvm hp-ux 11.23 - asm or raw??

From: Svetoslav Gyurov <>
Date: Tue, 12 Feb 2008 18:38:03 +0200
Message-ID: <>


Hi Ujang,

Yes, HP are right and you have mix the terms and technologies. If you look carefully of my mail, I neved said that you need raw LVM or pvlink for running RAC without SG.

You have two storage options for RAC:
- First is to use directly physical disks as they appear in "ioscan -fnC disk" such a disks are /dev/rdsk/c11t5d0 or /dev/rdsk/c6t5d0, in this case the device names must be the same on all nodes, you have no dependencies, less control and no warnings if someone execute pvcreate on such a physical disk, no pvlinks. Also no need of SG/SGeRAC.
- Second if to use Shared LVM. In this case you create volume group with the appropriate logical volumes and propagate it to all nodes. After that you activate the volume group in shared mode (this is were you need SGeRAC) then you can you these logical volumes for the CRS/RAC installation. One thing to note is that you cannot activate the volume group in shared mode unless the cluster has started. Here you have for sure identical logical volume names, better control, dependencies integrated with SGeRAC Toolkit and pvlinks. Using SG/SGeRAC is a MUST.

So in both cases you have raw devices, first they are physical disks / LUNS (NO LVM) and second they are raw logical volumes (Shared LVM).



Ujang Jaenudin wrote:

the little conflict now going on between me and hp :)

The final configuration on the machine is:
1. each machine has 2 HBA
2. raw LVM configured with pvlink on both nodes
3. OCR & voting disk are placed on that raw LVM
4. oracle datafiles put on ASM (disk which formed asm comes from
LUN/disk devices)
    I created script for manual failover in case 1 HBA failure.
5. no service guard at all.
6. sadly HP said that activate raw LVM on 2 nodes is not supported :(
7. for that kind of configuration HP service guard should be in place - HP
8. I got confirmation from metalink that the above configuration is
fully supported
9. anyone has the same configuration? please share for the future problem :)


On Feb 5, 2008 5:25 PM, Svetoslav Gyurov <> wrote:

 Sorry for the late reply. Well I don't have experience running Oracle RAC
without SG, but I know installations which are running without SG, using
physical raw disks and the cluster is running without any problems. The
performance should be the same, in both cases you are using raw devices.
About stability and management using SG is better by the reasons I said in
the previous mail.


 Ujang Jaenudin wrote:

thanks for the details,
you are correct that crs 10g didn't state that we must use slvm.

for this...
"> ............ snip ......

 you can use disks device files as well, BUT first
there is no guarantee that the names of the devices files will be the
same at all nodes and second if someone decide to execute pvcreate at
some of these files there is no warning message and all your data will
be gone."

 how about the experiences about it? stability? performance?
and all over pros & cons?

I really want to use this kind of solution, due to service guard license.


On Feb 1, 2008 4:20 PM, Svetoslav Gyurov <> wrote:

 Hi Ujang,

 From Oracle 10g and appearing of Cluster Ready Services it is not
necessary to use SLVM, you can use disks device files as well, BUT first
there is no guarantee that the names of the devices files will be the
same at all nodes and second if someone decide to execute pvcreate at
some of these files there is no warning message and all your data will
be gone.

About your questions:
1. If you want to use SLVM you need to use Service Guard and Service
Guard Extension for RAC.
2. LVM natively have alternate links which offers you failover and not
load balancing if this is what you called multipath. Better way to have
real multipath (load balancing and failover) is to use Secure Path
depending of the mode of the storage (Active-Passive or Active-Active)
and this is for HP-UX 11iv2 (HP-UX 11iv3 does have native multipath for
AA mode).
3. Yes, I think it is good idea. Depends if you use SLVM then your can
use ASM over SLVM raw device and yes you have at least better management.
4. Yes, it used to be impossible, but before two years HP released
Service Guard Extension for RAC 11.17 which offered new functionality
called SNOR (Single Node Online Reconfiguration), it is also available
as a patch. Actually this new feature gives you the ability to shutdown
all the nodes in the cluster but one and then on this particular node
you can change the mode of the volume group without deactivating it,
make the appropriate changes, propagate the change to the other nodes,
move the volume group back to shared mode and then activate it at all
other nodes. For more information please read:
5. In the concepts of HP-UX this is called APA (auto port aggregation),
bonding is on Linux and timing is on Windows. Actually Service Guard
cannot aggregate ports, but can failover NICs by configuring and using
standby network interfaces i.e. your Service Guard is using lan0 for
HEARTBEAT and lan1 is standby network for interface lan0. So in case of
failure of lan0, Service Guard will automatically bring lan1 online and
try to resume the connection to the other node(s) through this interface.

My personal opinion is to use SLVM over SGeRAC for several reasons:
1. Control - SG is flexible and offers better control. By using raw
device files once the machine boots the Cluster Ready Services are
started immediately and you have less control.
2. Identical logical volume names on all nodes on the cluster and naming
3. Some kind of protection - accidentally doing pvcreate will be refuser
because the device is already initialized
4. Last but not at least Service Guard support for the SGeRAC Toolkit
giving you integration between SGeRAC and Oracle10g stack. Better
control by using multinode packages, package dependencies, cluster
interconnect subnet monitoring and several other good features.

Hope it helps.


Ujang Jaenudin wrote:


I have itanium machine and hp-ux 11.23 installed, with 2 hba for each
I plan to use Shared LVM - raw.

- I plan to not use serviceguard
- is shared LVM natively support multipath (i means there is no
multipath software from storage)
- is it good idea to use ASM on top of shared LVM raw device?? - i
thinking of easy management...
 i heard on shared LVM could not doing online changes.....
- is NIC bonding/teaming can be configured without serviceguard??

thanks for the sharing....



-- Received on Tue Feb 12 2008 - 10:38:03 CST

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