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Cloud Assembly Support for Multiple Disks Clusters, Disk Sizes per Template & SCSI Controller Management.

With the Introduction of Realize Automation 8.4 & Realize Automation Cloud March Release, Cloud Assembly has now the ability to specify SCSI disk placement, perform 2nd day Disk Operations in Muti-Disk Templates, deploy a Cluster of Disks then attach them to a Cluster of Machines , among some other Disk related operations.

The ability to use different SCSI controllers is important for performance reasons and it is mandatory for some deployment types, such as Oracle Real Application Clusters (RAC).

Then for managing a SCSI disk, you must specify and know its SCSI Controller and Logical Unit Number (LUN). For a vSphere Disk Object, you could now use Cloud Assembly to assign both values in the Cloud Template.

In order to assign a SCSI Controller and LUN, the following Cloud Template properties are available:



Let’s take a look into the following example to understand further both properties. In the code below, a couple of Disk Resources, Disk_1 and Disk_2 are connected to the same SCSI_Controller_3 and have assigned Controller Unit Number 0 and 1 respectively, in the other hand, Disk_3 will leverage SCSI_Controller_2 .

When instanced, you will get a list of the Attached Volumes and each Volume will present its associated properties (including the SCSI Controller and LUN Information) and expose 2nd day Actions, such as Resize Disk.

Under the vSphere Machine Storage you will be able to easily identify which Disk Resource is using what SCSI Controller and associated Unit Number.

Please note that, it is possible to specify the SCSI Controller and omit the Unit Number, in that case, assignment of the SCSI Controller matches the value you enter and the unit number is set to the first available Unit number under that Controller.

You also may omit both, the SCSI Controller and Unit Number, in this case, assignment is set to the first available SCSI Controller, and the first available Unit Number under that Controller.

Please note that Cloud Assembly no longer deploys SCSI disks in random order, SCSI controllers and disks are numbered in order, with zero being first. Each SCSI Controller can support SCSI Disks of Unit Numbers 0–15 and you cannot omit the SCSI Controller and specify only a Unit Number.

Don’t forget, you could make the design a lot more dynamic by using inputs to allow your customers to specify which SCSI Controller and Unit Number to use at Request or Update times.

You could find more examples at VMware Docs for Cloud Assembly.

Switching gears, a new Cloud Assembly feature is allowing you to craft and deploy a Cluster of Machines and attach a Cluster of Disks.

In order to do that, you could take advantage of the allocatePerInstance resource flag, count.index and map_to_object expression syntax in your Cloud Templates.

Consider this example, I would like to create two VMs and attach a couple of Disks on them, normally in this situation, I would have to include 4 Disk definitions in my Cloud Template and have them individually mapped to each specific VM.

However with this new resource flag and expressions, we could simplify the implementation, reduce the number of code lines in my Cloud Template and still meet my requirements as follows:

You could see how leveraging the map_to_object , we could indicate that Disk 0 and 2 (out of the 4 total disks created) must be attached to VM app0 and similarly the remaining Disks to VM app1.

But let’s not stop there, you could define a variable number of VMs, each having a variable number of Disks, and both be collected from your customer input.

And yes, if you were wondering, you could resize all these disks independently as needed. More examples at VMware Docs for Cloud Assembly.

And finally, Realize Automation 8.4 has implement independent 2nd day actions, for each Disks that are created as part of the original VM Template, you could find more detailed information in this blog: Better vRA Support for disks which are part of an image template.


vRealize Automation keeps evolving and providing more granular Out-Of-the-Box capabilities when it comes to Disk Management & 2nd Day Operations, which are as important (may be more) as Day 1 operations.

Related Links:

Announcing vRealize Automation 8.4

Announcing What’s New in vRealize 8.4

vRealize Automation Integration Enhancements with Azure

vRealize Automation Cloud Assembly’s new feature Secure Properties


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