With Erasure Coding we can shrink write-cold data even more to have less used space on the extend store. I’m not going to explain how this works as Nutanix has done a great job explaining this already (Link, Link). In this blog post I want to show when Erasure Coding kicks in and how much data reduction I got.
My lab is a 4 node cluster (which is the minimum nodes to enable Erasure Coding) so I will have a saving approximately 25%. This is because I have a strip size of 2/1 (2 data blocks and 1 parity block) and off course 1 empty block for the rebuild.
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/erasure-coding-savings-1024x385.png)
Lets put this to the test. I have created the following storage container:
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/ec-sc-1024x160.jpg)
The “Erasure-Coding” storage container is create with no storage optimisation enabled except Erasure Coding.
There are 4 Windows virtual machine created with their bootdisk (100GB) on the default workload container and a 200GB data disk on the erasure coding storage container:
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/windows_vms-1024x405.jpg)
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/200gb_ec-1024x291.jpg)
Then I generated 100GB of random data on each virtual machine on the disk which is on the erasure coding enabled storage container:
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/100gb_ec-1024x263.jpg)
I’ve waited a full curator scan to be sure storage optimalisation is up to data 😉
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/curator_running-1024x688.jpg)
As you can see in the screenshot the actual data is still 400GiB on the Storage Container:
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/full_data-1024x457.jpg)
And to be more specific the curator reduction report is also showing the same numbers (800GB as this is the raw data, as I’m running Replication Factor 2).
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/reduction_report-1024x666.jpg)
Now lets wait for 7 days. To see what erasure coding is doing with the data.
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/after7_days_reduction.jpg)
And the curator data reduction report looks like this:
![](https://www.jeroentielen.nl/wp-content/uploads/2024/01/7days_reduction_report.jpg)
Please keep in mind that erasure coding is only for specific type of workloads, for example:
- Write once, read many (WORM) workloads;
- Backups;
- Archives;
- File servers;
- Log servers;
- Email (depending on usage).