vSphere API – Page 24

VSAN Flash/MD capacity reporting

04.29.2014 by William Lam // Leave a Comment

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.

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.

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:

Here is an example screenshot for the PowerCLI script:

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.

Exploring VSAN APIs Part 9 – VSAN Component count

04.09.2014 by William Lam // 4 Comments

The last topic that I would like to explore before concluding my VSAN API blog series are some of the advanced VSAN disk statistics that are available for either troubleshooting or informational purposes. One such statistic that would be handy to know about is the number of VSAN Components per ESXi host, which I have already demonstrated in my recent VSAN configuration maximum query script and VSAN PowerCLI vCheck Plugins.

These disk statistics are made available through the VSAN InternalSystem manager and using the QueryPhysicalVsanDisks() vSphere API method, we can either retrieve all or a specific set of properties for each ESXi host. I have created a sample vSphere SDK for Perl script called vsanDiskStatsQueries.pl that will demonstrate the use of this API.

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

Here is an example of running the script against a VSAN Cluster which will produce the number of VSAN components for each ESXi host:

./vsanDiskStatsQueries.pl --server vcenter55-1.primp-industries.com --username root --cluster VSAN-Cluster

If we take a look at the script, you will notice we filtered on two specific properties: lsom_objects_count and owner. One thing to note is the output for this method is JSON string, so you will need to parse the output accordingly.

The owner property indicates the UUID of a specific ESXi host and the lsom_objects_count represents the number of VSAN components. To be able to identify the particular ESXi host and compare it to the owner property, we use the QueryHostStatus() API which was discussed in Exploring VSAN APIs Part 5. Once we have a match for the current ESXi host, we simply extract the lsom_objects_count property which I use a simple hash table to keep track of the results and display it at the very end of the script.

This concludes my 9-part series of exploring the new VSAN APIs. Hopefully for those of you who followed the series have enjoyed it, I know I definitely had fun learning about the new APIs and how you can automate every aspect of VSAN from a scripting and programmatic perspective.

VSAN vCheck Plugins

04.07.2014 by William Lam // 5 Comments

After creating my VSAN Configuration Maximum query script I thought it would also be useful to create an equivalent set of VSAN vCheck Plugins. For those of you who have not heard of or used vCheck (pretty rare unless you do not use PowerShell/PowerCLI in your environment), it is a PowerShell reporting HTML framework created by Alan Renouf. vCheck allows you to schedule a series of PowerCLI scripts/checks against your vSphere environment and produces a daily report on the things you care most about such as datastore capacity being under a certain threshold or potential snapshots growing out of control in your environment.

Given this is the primary use case for vCheck, I figure it would make sense to implement these same set of VSAN configuration maximum checks in vCheck as well. This would also give me the opportunity to learn more about vCheck as I have never used it before. If you are new to vCheck, I highly recommend you check out Jonathan Medd's article on how to get started with vCheck here.

Here is a sample report of a real VSAN environment to get an idea of what the report could look like: VSAN-vCheck-Report.html

Below are the VSAN vCheck Plugins that I have created which also includes a bonus plugin which reports on the capacity of a VSAN Datastore. You can pick and choose the VSAN plugins that you want to use in your environment and then customize the threshold parameter for each report based on your requirements.

For those of you who are looking to evaluate VSAN in their environment, hopefully these VSAN vCheck reports will come in handy. If there are others that you feel that might be useful, feel free to leave a comment or contribute back to the vCheck project on Github.