Thursday Oct 24, 2013

Adding an existing Control Domain to a Server Pool

I got a question about LDoms:

"Is it possible to move a Control Domain built through Ops Center with pre-existing LDoms into a server pool? If so, do I need to delete and recreate anything?"

Yes, you can do this. You have to stop the LDom guests, and then you can add the CDom to a Server Pool. If the guests are using shared storage, you should be able to bring them up in the Server Pool. If the guests are not on shared storage, you can use the Migrate Storage option to bring their storage in.

Thursday Aug 01, 2013

LDoms and Maintenance Mode

 I got a few questions about how maintenance mode works with LDoms.

"I have a Control Domain that I need to do maintenance on. What does being put in maintenance mode actually do for a Control Domain?"

Maintenance mode is what you use when you're going to be shutting a system down, or otherwise tinkering with it, and you don't want Ops Center to generate incidents and notification of incidents. Maintenance mode stops new incidents from being generated, but it doesn't stop polling, or monitoring, the system and it doesn't prevent alerts.

"What does maintenance mode do with the guests on a Control Domain?"

If you have auto recovery set and the Control Domain is a member of a server pool of eligible systems, putting the Control Domain in maintenance mode automatically migrates guests to an available Control Domain.  When a Control Domain is in maintenance mode, it is not eligible to receive guests and the placement policies for guest creation and for automatic recovery won't select this server as a possible destination. If there isn't a server pool or there aren't any eligible systems in the pool, the guests are shut down.

You can select a logical domain from the Assets section to view the Dashboard for the virtual machine and the Automatic Recovery status, either Enabled or Disabled.

To change the status, click the action in the Actions pane.

"If I have to do maintenance on a system and I do not want to initiate auto-recovery, what do I have to do so that I can manually bring down the Control Domain (and all its Guest domains)?"

Use the Disable Automatic Recovery action.

"If I put a Control Domain into maintenance mode, does that also put the OS into maintenance mode?"

No, just the Control Domain server. You have to put the OS into maintenance mode separately.

"Also, is there an easy way to see what assets are in maintenance mode? Can we put assets into, or take them out of, maintenance mode on some sort of group level?"

You can create a user-defined group that will automatically include assets in maintenance mode. The docs here explain how to set up these groups. You'll use a group rule that looks like this:


Tuesday Jul 09, 2013

Limits on LDom numbers

I got a question - or a few linked questions - about installing LDoms in a Server Pool through Ops Center.

I have some T5240s (2x SPARC T2+) and some T5440s (4x SPARC T2+) running as standalone Control Domains with some LDoms each.

1. Is there any limit to the number of CDoms per Server Pool within Ops Center?

No, there is not.

2. What about the number of LDoms per Server Pool, per CDom, or per server?

The only limitation on the number of LDoms is that a server or physical domain can't have more LDoms than it has threads, or have more than 128. If you get close to that limit and start having LDoms with one thread, performance will start to suffer.

3. Is it possible to mix them within the same server pool?

Yep. Depending on your LDom version and the hardware, live migration might not be possible, but you can have server pools with different hardware types, and automatic failover will work fine.

If you're also looking at setting up Server Pools through Ops Center, we put together a how-to about setting up a Server Pool which could be helpful. There's also a white paper on the OTN with best practices for setting up a virtualized SPARC environment.

Tuesday Jul 02, 2013

Migrating an LDOM from a T4 to a T5

I got a question about LDoms:

"Is there any restriction against migrating LDoms between the T4 and T5 platforms?"

The only restriction is that, at present, you can't do a live migration. However, with Ops Center 12.1.4, you can put T4 and T5s together in a Server Pool and either manually migrate the LDoms to a new host or configure them for automated cold-migration failover.

Take a look at the Server Pool and Oracle VM Server for SPARC chapters for more information.

Friday Jun 21, 2013

FAQ: Creating a new LDOM domain

I got a question about creating LDOM domains:

"I have a Server Pool set up, and I need to create a secondary LDom domain on a machine in the pool. When I click on the machine, though, the 'create logical domain' command is grayed out. The machine still has available CPU threads and free RAM. What's going on?"

This one has an easy answer. In a Server Pool, the Create Logical Domain action is under the pool's actions, rather than the individual machine's actions. This is because the Server Pool decides where to put the new domain based on the Server Pool's placement policy. So, in this case, you need to select the Server Pool in the Assets section, and then create the new domain from there.

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This blog discusses issues encountered in Ops Center and highlights the ways in which the documentation can help you

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