RAC oracle

[Francesco_13]

Hi,
we planning to install oracle cluster.
I need service guard software or other HP-UX extension?

Thanks.
Best regards

[Victor Fridyev · Accepted solution]

Hi,

Oracle RAC is an independent product. You need nothing additional.

[Serviceguard for Linux]

If you are implementing Oracle RAC (9i) on an HP-UX system you need SGeRAC.

If you are implementing Oracle RAC on Linux, you do not need Serviceguard.

[Carsten Krege]

HP's High Availability Product - ServiceGuard OPS Edition - has gone through a product name change and will now be called ServiceGuard Extension for RAC (or SGeRAC). This change has been made to provide better visibility for its capabilities with Oracle RAC (Real Application Cluster (= RAC) is Oracle's new name for OPS):

The name changes requires also a change of the product numbers:

New: SGeRAC:
T1859BA (HPUX 11.11)
T1907BA (HPUX 11.23)
Old: SGOPS Edition: B5161FA

Beginning with version A.11.14.01 (for HPUX 11.22) the product structure of SGeRAC has changed so now, SGeRAC, does not contain SG code anymore. SGeRAC is now an add-on product to SG, meaning that SG has to be installed first before you can install ServiceGuard extension for RAC (SGeRAC). SGeRAC and SG releases and version numbers will continue to be concurrent.

Beginning with version A.11.14.01 the SGeRAC product depot will not deliver those files which are shipped in the ServiceGuard product. The depot for SGeRAC will include only four files: cmgmsd, 32-bit and 64-bit version of NMAPI2 shared libraries (libnmapi2.1) and gmsetlog.

Also starting with SGeRAC A.11.14.01, SGeRAC patches will be released
independently from SG. The SGeRAC patch process will be same as the SG process. Some fixes may just required one SGeRAC patch, some fixes may require an SG plus a SGeRAC patch.

Carsten

[Fred Ruffet]

Hi !

You don't *need* SG. You can install RAC without it and run without it.

IMHO SG is intended to help you in managing a FailOver Cluster, whereas RAC is intended to run Active/Active clusters.

Regards,

Fred

[Carsten Krege]

Well, in order to run Oracle RAC installation you need some high availability software. The common approach on HPUX is to use ServiceGuard together with Serviceguard Extension for RAC (SGeRAC).

I believe with Oracle 10g you can also use the new Oracle built-in Cluster Ready Services Clusterware as high availability software. To my knowledge this is based on TruCluster (from HP) and fully provided and supported by Oracle. If this is an option for you, you should check with Oracle.

Carsten

[Fred Ruffet]

I understand this, Carsten, but if I understand, SG's goal is to detect failures on a node to launch things on the other one.

What needs to be launched on the second node when your running RAC on an active/active cluster ?

Regards,

Fred

[Francesco Campalastri]

You do not need MC/SG to install Oracle RAC but you need MC/SG to avoid single point of failure.

You have to make all the oracle instance communicating trough a very high speed channel as LAN Gigabit or fabric switched SAN.

If this link (dlm) is down ALL the oracle instance freeze because there are no more information about every SGA.

MC/SG let you duplicate the high speed channel for dlm (and many other thinghs) and I suggest you to use it very warmly.


Bye
Francesco (me too)

[Fred Ruffet]

Thanks Francesco (you too :) !

This seems to be a great argument for SG. SG has just passed from the "good thing" status to the "necessary" one.

Anyway, SG seems to include many thing just for this... As long as SG is a collection of other products, couldn't the one bringing this feature be taken appart ?

Regards,

Fred

[Carsten Krege]

Fred,

> I understand this, Carsten, but if I
> understand, SG's goal is to detect
> failures on a node to launch things on
> the other one.

This is basically true. More important on SGeRAC is the capability to provide group membership services. The base advantage is that it basically allows to run multiple Oracle instances on a single node.

> What needs to be launched on the second
> node when your running RAC on an
> active/active cluster ?

Each node starts one or more Oracle packages that do not failover to the other node in case of a failure. If one Oracle package fails, the other node takes over the load (managed by some external connection software).
Furthermore you can define additional packages that just behave like on a normal SG cluster.


The Oracle manual "Oracle Real Application Clusters Installation and Configuration Guide" on http://otn.oracle.com/documentation/database10g.html, specifically http://download-uk.oracle.com/docs/html/B10766_02/prehpux.htm#sthref860 (login required) lists the software requirements on HPUX:

"Real Application Clusters:

HP Serviceguard A11.15.00 or higher
HP Serviceguard Extension for RAC A11.15.00 or higher

HyperFabric software - Required if you want to use Hyper Messaging protocol as the cluster interconnect

.01 or higher

Note: HP Serviceguard is required only if you want to use HPâ s shared logical volumes for CRS or database files."

This is a good point. When you want to use LVM, you need to activate your volume groups shared (vgchange -a s ..) and this feature becomes only available with SGeRAC installed.
Veritas Cluster Volume Manager also integrates with SGeRAC.

If you're not using any of these (not sure this is possible), you still need the Oracle Cluster Ready Services on each of the node. THis is at least my understanding.

The Oracle manual also states on
http://download-uk.oracle.com/docs/html/B10766_02/intro.htm#i1030440 :

"For functionality required from the vendor clusterware, Oracle's clusterware provides the equivalent functionality. Also, using Oracle clusterware reduces installation and support complications. However, vendor clusterware may be needed if customers use non-ethernet interconnect or if you have deployed clusterware-dependent applications on the same cluster where you deploy RAC."

Cars