METRO Cluster

[dragana s-v]

Does anyone know is software component of METRO Cluster different from regular MC-SG product? I know the addition would be interface for SAN device but rather than that is the MC-SG the same or not?

[Uday_S_Ankolekar]

Hi,

Overview of MetroCluster/CA

MetroCluster is a set of scripts that work in an MC/ServiceGuard cluster to automate failover to alternate nodes in the case of disaster in a campus or metropolitan cluster. The MetroCluster/CA template contains the following files, installed in /opt/cmcluster/toolkit/SGCA:
sgcapkg.cntl
The MetroCluster/CA control script template. This template must be customized for the specific Disk Array XP Series and HP 9000 host system configuration. Copies of this template must be customized for each separate MC/ServiceGuard package.

Samples
A directory containing sample convenience shell scripts that must be edited before using. These shell scripts may help to automate some configuration tasks. These scripts are contributed, and not supported. This directory also contains sample Raid Manager configuration files and other examples.


Have a look at www.docs.hp.com/hpux/onlinedocs/B7660-90006/B7660-90006.html

[Sridhar Bhaskarla]

Hi,

The nodes in the metropolitan cluster are not going to be adjustant. So, there are obvious limitations to the connectivity to the Disk systems even through SAN. So, it is not possible to share the same set of disks. To achive this, you need to have two seperate disk frames that are continously sync'ed up through ESCON links. You need to use an additional software component to establish and break/resync the mirrors. XP Raid manager for XP systems or symmetrix CLI for EMC. This will be part of your control script. You may also want to configure Arbitrator Nodes to maintain the quorum.

I haven't done this yet but am planning to. There is good documentation out there at docs.hp.com.

-Sri

[dragana s-v]

Hi All,

Thanks for the reply. I have posted my question because in our environment we want to implement Metro Cluster without using EMC or XP. I know we have AutoRaid and yes, there will be arbitrary node. I don't have more details but, I have concern that this option will AutoRaid wont work. If it is possible to make it work how it can be achieved?
Regards,
Dragana

[A. Clay Stephenson]

Hi:

I think your only practical alternative is to choose disk arrays that can continuously 'sync-up' behind the scenes like XP's or EMC. While I can at least concieve of a few techniques that might keep other arrays synced I certainly wouldn't bet the company on it. Normally, when you are looking at this sort of solution, money isn't the primary concern; reliability is. It may be that you can change the question to 'can I locate the data centers closer together but still in separate buildings so that more conventional mirroring becomes possible?'. But if the question remains a true MetroCluster, then you are going to be forced to use the high-end arrays.

My 3 cents, Clay

[Bill Hassell · Accepted solution]

There's nothing in the Autoraid disks that will support data synchronization over a network so the ability to use MC/SG will not work. This isn't a simple task at all since the concept of MC/SG is an essentially seamless transfer of an application package from one system to another, and for that to work, the same data must exist on both systems. Getting two independent disk arrays to stay in sync is a non-trivial task, especially when the sync process could severely slowdown the active server (waiting for the remote writes to complete).

[dragana s-v]

Thanks a lot everyone !!!

Dragana