HA & Failover options

Hi all,

Let me give a brief background before i pose my questions:

Background:
We are currently working on the architectural phase of a program which will involve implementing a given solution for multiple companies. We have proposed to have physically separate organisation specific instances for all the technology components (App Server, DB Server, Security Infrastructure, Web Server, Infrastructure services for Systems Management, Backup & Recovery). Major softwares used are Oracle Application Server 10g Release 3 and Oracle Database Release 2. The project has some strict HA & Failover requirements

The OS choices are AIX 5.2/5.3 and RedHat Linux 3/4. The box choices are a) Commodity Servers: IBM x Series or HP ML/DI Series with Windows 2003 Server or Red Hat Enterprise Linux ES 3.0 or 4.0 b) Unix Server IBM P570 Series with AIX 5.2 or AIX 5.3.

The HA software choices are IBM's HACMP/XD, Veritas Global Cluster Software, RAC and Data Guard (DG), Oracle Application Server's Clustering features.

Constraints:

1. We have historically not used RAC or DG or Oracle Application Server Clustering in this shop
2. We have performed an exercise of aligning different technology components. For instance, Database instance and Reports Server would sit together in the same physical box, All infrastructure services would sit in the same box c)We have also made platform choices for all technology components other than Application Server and Database Server

Questions:
a) For database which is the best cluster solution: HACMP/XD or VCGS or RAC+Oracle Clusterware+Dataguard? I'm aware that in hardware based clustering, the passive instance doesn't get used whereas in an Oracle RAC solution it does get used. But i don't want to make use of mid-range servers (p570 is one) along with Oracle RAC and a hardware cluster since my cost shoots up. I would preferably use commodity server clusters when deploying an Oracle RAC solution. Share your thoughts on this. Also, how stable is Oracle clusterware? Please give your estimation of the three options.

b)Do you have any large scale implementation experience of Oracle DB on low end boxes such as IBM x Series/ HP ML/DI Series with either Windows 2003 Server or Red Hat Enterprise Linux ES 3.0 or 4.0? If yes, share your experiences.

c) n+1 vs n+n

Currently we are proposing a 2*1 instance configuration across two locations for the database based on it being a middle-path solution. i.e., it is not exhorbitantly priced and at the same time it offers reasonable failover and HA facilities. We are aware of the problems in this option such as no protection from instance or node failures at the secondary site, potential performance degradation at the secondary site, manageability problems owing to asymmetric configurations across primary and secondary sites

Can you provide your thoughts on n+n or n+1 configurations when dealing with multiple database instances?

d) Generic vs Specific clustering solutions

Veritas Global Cluster Software has the advantage of being platform independent whereas HACMP doesn't have. Does this factor ever play a role in deciding the cluster software?

d) Cost

>From a cost perspective out of the three options (IBM's HACMP/XD,
Veritas Global Cluster Software, RAC and Data Guard) which one is the cheapest and which the costliest?

e) When using Data Guard is there a requirement for Global clustering software or will the local clustering software itself perform the job? Also, how instantaneous is failover to the secondary site with data guard when failures occur in the primary site?

e) Data replication

For data replication across primary and secondary sites we have options such as a) SAN or NAS based disk replication b) Data Guard. What are the advantages/disadvantages in these two options?

f) Oracle Application Server

Historically we haven't used Application Server's clustering features in this shop. For load balancing we have used Network Load balancers. We didn't use Application Server's clustering features in the past because the earlier releases of Oracle Application Server had some bugs in this aspect. What is current status? Received on Tue May 09 2006 - 06:35:37 CDT