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Exploring VSAN APIs Part 10 – VSAN Disk Health

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In additional to monitoring storage and host utilization of your VSAN Cluster, the health of the individual disks contributing to your VSAN Cluster is probably one of, if not the most important thing to keep an eye on. In the vSphere Web Client, this information can be accessed by navigating over to the VSAN Disk Management tab as seen in the screenshot below.

vsan-disk-health-0
Even though this information is available from the UI, it would also be useful to be able to extract this information programmatically using the vSphere API either for external monitoring or informational purposes. I recently had did some work on this, so I figure I might as well share an example script that demonstrates this functionality. To do so, I of course created a sample vSphere SDK for Perl script called vsanDiskHealth.pl

Disclaimer:  These scripts are provided for informational and educational purposes only. It should be thoroughly tested before attempting to use in a production environment.

The script leverages the QueryPhysicalVsanDisks() API which accepts a list of properties to collect on an individual VSAN Disk. You can also leave the method blank, in which all properties will be returned. For our use case, we are collecting a sub-set of the properties which includes: owner, uuid, isSsd, capacity, capacityUsed, disk_health.

To check the current health of your VSAN Disks, you just need to specify the name of a VSAN enabled Cluster:

./vsanDiskHealth.pl --server .vcenter55-1 --username root --cluster VSAN-Cluster

vsan-disk-health-1

  1. Exploring VSAN APIs Part 1 – Enable VSAN Cluster
  2. Exploring VSAN APIs Part 2 – Query available SSDs
  3. Exploring VSAN APIs Part 3 – Enable VSAN Traffic Type
  4. Exploring VSAN APIs Part 4 – VSAN Disk Mappings
  5. Exploring VSAN APIs Part 5 – VSAN Host Status
  6. Exploring VSAN APIs Part 6 – Modifying Virtual Machine VM Storage Policy
  7. Exploring VSAN APIs Part 7 – VSAN Datastore Folder Management
  8. Exploring VSAN APIs Part 8 – Maintenance Mode
  9. Exploring VSAN APIs Part 9 – VSAN Component count
  10. Exploring VSAN APIs Part 10 – VSAN Disk Health

How to finally inject OVF properties into VCSA when deploying directly onto ESXi?

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One of my biggest pet peeve when it comes to deploying the VCSA (vCenter Server Appliance) and other OVF/OVA directly onto an ESXi host is the lack of OVF property support. If you have deployed the VCSA before, you are probably aware of the different user experience when deploying to a vCenter Server versus deploying directly to an ESXi host. For those of you who are not familiar, the difference is when you deploy an OVF/OVA that contains custom OVF properties such as the VCSA, you have the ability to provide input to these parameters when deploying to a vCenter Server as seen in the screenshot below.

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VSAN Flash/MD capacity reporting

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One of the capabilities that is available with VSAN when creating a VM Storage Policy is the ability to specify the amount of to Flash to reserve for a Virtual Machine object as a read cache. For Virtual Machines that require high levels of performance, you can assign this policy to the Virtual machine and VSAN will ensure a percentage of the Flash capacity is provided to your workload.

vsan-flash-md-capacity-report-3-NEW
A couple weeks back I was asked whether it was possible to report on the total amount of Flash capacity available to a VSAN Cluster including what has been reserved and in use. I thought that this was a great idea as users would probably want to be able see their utilization over time and ensure they do not over provision their Flash capacity.

For those of you who have used RVC, this information is somewhat available today using the vsan.disks_stats command. The only problem is that this information is only provided at a per device level for each ESXi host and not in an aggregate view for the entire VSAN Cluster.

vsan-flash-md-capacity-report-0
Leveraging the work I had done earlier with exploring the VSAN API and looking at the VSAN component count, I was able to extract the necessary information that I was looking for to provide an aggregate view. To demonstrate this functionality, I have created two sample scripts: vSphere SDK for Perl script called vsanFlashAndMDCapacity.pl and PowerCLI script called vsanFlashAndMDCapacity.ps1

Disclaimer:  These scripts are provided for informational and educational purposes only. It should be thoroughly tested before attempting to use in a production environment.

Both scripts work exactly the same way, you just need to connect it to a vCenter Server that has at least one VSAN Cluster. The script will automatically search for all VSAN enabled vSphere Cluster and provide the following information:

  • Total SSD Capacity
  • Total SSD Reserved Capacity
  • Total SSD Used Capacity
  • Total MD Capacity
  • Total MD Reserved Capacity
  • Total MD Used Capacity

Here is an example screenshot for the vSphere SDK for Perl script:

vsan-flash-md-capacity-report-1
Here is an example screenshot for the PowerCLI script:

vsan-flash-md-capacity-report-2
One question I had myself while looking at the results was regarding the "Used" property and what it meant. I think this is best explained with an example after learning about the details from engineering.

Lets say there are 2 VSAN objects:

  • Object1: Configured size: 100GB, space reservation 10%, actual data written 5GB.
  • Object2: Configured size: 100GB, space reservation 10%, actual data written 15GB.

This would mean:

Object1:
Configured/Provisioned: 100GB
Reserved: 10GB
Physical Used: 5GB
Used: 10GB

Object2:
Configured/Provisioned: 100GB
Reserved: 10GB
Physical Used: 15GB
Used: 15GB

The "Used" property is then calculated as the MAX(Physical Used, Reserved). I have also shared this information with engineering, perhaps they may consider adding this information to RVC 🙂 If you think this is something you would like to see in RVC, please leave a comment.