No csum errors in scrub report

Hi ,
I’m getting some “No Csum” counts on all scrub reports. What does this count means and is this something that needs attention?

Pool name: main

Scrub Status: finished

Scrub Statistics
Attribute Value
ID 4
Start Time December 1st 2017, 4:42:02 am
End Time December 1st 2017, 4:46:40 am
Data Scrubbed 92.78 GB
Data Extents Scrubbed 1542763
Tree Extents Scrubbed 9713
Tree Bytes Scrubbed 159137792
Read Errors 0
Csum Errors 0
Verify Errors 0
No Csum 7104
Csum Discards 0
Super Errors 0
Malloc Errors 0
Uncorrectable Errors 0
Unverified Errors 0
Corrected Errors 0
Last Physical 118251061248

@belka A belated Welcome to the Rockstor community.

This is normal, as long as you have no entries with Error in the name you should be good. I’m afraid I am not clear on exactly what this means but I’m assuming it’s encountering elements that are currently unused and so have no csum as their is no data to have a check sum for. If you look to the issue that added this UI feature you will see an example of the output for a know good disk that also has a 228 count for “No Csum”:

You will also see in that issue an example of what the UI looks like if any errors have been found.

Apologies for not being able to answer this query fully.

If any forum members can find the exact definition of the “No Csum” in the “btrfs scrub status” output for a finished scrub that would be great as I should know and just haven’t gotten around to researching this.

Hope that helps.