Determining which servers are part of my app_cluster?

[Vince_Noir]

Hi,

I've inherited a NBU envirnonment and I'm trying to determine whether media server clustering is setup correctly. Running an nbemmcmd -listhosts shows me two app_cluster entries with the windows cluster name (all good). How can I determine that the correct nodes have been added to the app_cluster?

7.5.0.6

Thanks

[revarooo]

try this:

 nbemmcmd -listhosts -list_app_clusters -masterserver <your_master_hostname> -verbose

[Marianne]

We would still like to see this post resolved:

https://www-secure.symantec.com/connect/forums/quesiton-regarding-restoring-cluster

Seems no app-cluster was created for those media servers?

[Vince_Noir]

Hi Marianne,

That's what I'm trying to do. 

Using the first answer as a guide, the command I ran was actually

nbemmcmd -listhosts -list_server_in_app_cluster -clustername <cluster>

Which did return the 2 cluster nodes that shuold be part of the cluster.

The part I'm stuck at is when you are to create a storage unit for the application. I can only see it when I create a basic disk, but then I can't create a disk pool from a basic disk. Is that correct?

[Marianne]

..........  but then I can't create a disk pool from a basic disk. 

Correct. Disk pools need Advanced Disk.

[Vince_Noir]

So can I use media server clustering with disk pools (and therefore Advanced Disks)?

[Marianne]

The High Availability Guide does not make any distiction between Basic and Advanced disk under the Adding disk storage units topic. 

I have in all honesty never tried to configure Advanced Disk in an app_cluster. 

Hopefully someone else on this forum has done it and can share experience.

The other alternative is to ask Support.

It was not supported in NBU 6.5: http://www.symantec.com/docs/TECH86340

I cannot find documentation to say if Advanced disk is supported or not in version 7.x.

[Vince_Noir]

I might just do that (ask support)

I've got a feeling that they won't be supported.

[Marianne]

The alternative will be to create BasicDisk STU per volume/lun and to group them in Storage Unit Group.

Problem is that they cannot be used in SLP.

Curious to know what Support says....

[Vince_Noir]

We use SLP so that would be a no go!

I'll let you know when I find out.

[Vince_Noir · Accepted solution]

Hi Marianne,

It's not supported, just got this back from support. 

I have discussed this issue with one of Backline Team Member and he confirmed that the App_Cluster configuration was meant for Media Manager Storage Units and not for Disk Storage Units.

We had similar feature called "Shared Disks" wherein multiple media servers were performing write operation, but this was causing many inconsistencies in Image DB, so we had to discontinue that.

In our scenario we are also looking for same thing which is not recommended and not possible to configure with. We also not recommend you to use App_Cluster configuration with Basic Disk Storage Unit. Though its working fine for you at this time. It may create your image database inconsistent.

Let me know if you have any further queries or concerns on this

Thanks.

[Marianne]

I have discussed this issue with one of Backline Team Member and he confirmed that the App_Cluster configuration was meant for Media Manager Storage Units and not for Disk Storage Units.

Fact is - this stament is incorrect.

The NBU HA manual clearly documents creating Disk Storage Units in an App Cluster under this topic:

Adding disk storage units

All steps are listed as well as the following under point 6:

Use the NetBackup Administration Console to create a disk storage unit for

each application. Specify the virtual name of the application as media server

name for the storage unit.

So, NO WAY is App Cluster meant for tape only. 

The manual is simply not saying Basic or Advanced...

The question here is about Advanced Disk.

Hopefully you have NOT agreed to close the case??

[Vince_Noir]

I've emailed him back asking him to clear up why the manual states disks!

[Marianne]

Please ask the engineer to carefully read through http://www.symantec.com/docs/TECH86340

In 2009, Symantec said (extract from TN):  

It is not known when AdvancedDisk and app_cluster on a Windows cluster will be supported.

Surely by now (4 years and many versions later) there should be a better answer....