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Windows 2000 Cluster can not share same disk on EMA12000 SAN

Michael Knight_1
Occasional Visitor

Windows 2000 Cluster can not share same disk on EMA12000 SAN

Hi,

I am trying to build a Win2k Cluster using shared storage from a EMA12000 SAN.

With one Windows box powered down, its partner can see and access the shared storage, and vice versa.

However, when they are both powered up, only one Windows box can access the shared storage. The other cannot see or access it.

This happens both before I install the MS Clustering Services, and afterwards. With the Cluster Service running on both nodes, one node will always control the Shared storage, with the other unable to see or access it as before. It does differ slightly in that when the cluster service is stopped on the first node, the shared disks are then re-assigned to the second node.

However, in order for the cluster service to run propely, both boxes must be able to access the shared storage at the same time.

I am using one Fibre Channel Host Bus Adaptor in each Windows box which then connects to a GBICS in the SAN's switch. The SAN is controlled by a Tru64 Cluster running StorageWorks ver 8.6. The Shared disk in the SAN has been 'zoned off so that only WinNT can access it. The remaining disks have been zoned for Tru64 access only. The Command Line Console has been disabled, and the SAN is running in multi bus failover mode.

Please help!
"There are ten types of person in this country: those that understand binary, and those that don't." Jeremy Paxman, 2003
5 REPLIES
Vincent Fleming
Honored Contributor

Re: Windows 2000 Cluster can not share same disk on EMA12000 SAN

I don't understand...

Only one machine in the cluster should be able to access the cluster disks at a time. ie: They should never see the same drives at the same time.

You should be able to assign some of the shared disks to one server, and the rest of them to the other server, though. They would each be able to access the array, but on different disks/Luns.

This is because the two cannot mount the same filesystem at the same time.

Can you try to describe your problem again?

Thanks,

Vince
No matter where you go, there you are.
Michael Knight_1
Occasional Visitor

Re: Windows 2000 Cluster can not share same disk on EMA12000 SAN

So the disks can only be accessed by the Node which currently 'owns' them as a resource.

If that's true (and I am very much learning MS Clustering as I go on) then my cluster is up and running.

I just felt that both machines should be able to at least see the shared disk at the same time. I understand your point about both file systems being unable to mount the same disk as the same time, I was thinking that the Cluster Service took over and imposed some kind of control onto it.

If thats it, then it's all done!

Thanks,

Michael
"There are ten types of person in this country: those that understand binary, and those that don't." Jeremy Paxman, 2003
Vincent Fleming
Honored Contributor

Re: Windows 2000 Cluster can not share same disk on EMA12000 SAN

Michael,

The MSCS software hides the LUNs from Windows until it needs to see them, so it does sound like you've got it right.

Happy computing!

Vince
No matter where you go, there you are.
Michael Knight_1
Occasional Visitor

Re: Windows 2000 Cluster can not share same disk on EMA12000 SAN

There is still something not quite right...

Without the MSCS software being installed, the two Win2K hosts cannot see the shared disk at the same time.

If one is powered down then the other can see it, and vice versa. But when they are both powered up at the same time, only one node can see and access the disk.

I understand the point about possible file corruption if both hosts can access the disk at the same time - but they cant access it full stop!

Am I missing something obvious again!?

Thanks,

Michael
"There are ten types of person in this country: those that understand binary, and those that don't." Jeremy Paxman, 2003
dentistcorn
Regular Advisor

Re: Windows 2000 Cluster can not share same disk on EMA12000 SAN

I've done this a billion times:
It seems you have not configured the disk to be a resource of the cluster. In fact... I know that's what the issue is. Try this:


1- Bring both nodes down.

2- If you haven't already create your storage units on the HSG80 and give them the appropriate Host access.

3- Only bring one node up.. say node A. In the LDM (disk manager) make sure you can see the new disk and give it a drive signature.

4- Refrain from upgrading the disk to Dynamic... Important!!!

5- Reboot

6- when node A comes back up ( node B is still off!!!) assuming clustering is installed and configured, add the new disk as disk resource to your cluster group.

7- Power up node B.

8- Both nodes should see the disk resource now.

At no time should both nodes see the new disk at the same time. One of the servers must be off until you have finsihed configuring your disk

Once Clusdisk takes over the disk, it becomes a resource of the cluster. Both nodes should now have access to the disk.

It's not enough to just install the cluster service. You must have a group configured and the disk must be a resource in that group. If not you will get excalty the issues you are seeing.

If you have a mixed OS environment, be extra careful to zone it out at the swicth and to use LUN masking or selective storage presentation. Also, check out compaq's guide to heterogenous SANs.