I figure out weird behavior with NFS (v4). We are experiencing problem with Jira Data Center and we found as the most possible reason slow response time on NFS disk (used for shared cache between nodes - so we need fast response time). OS is Debian 11.
We are using Atlassian support tools utility mentioned in this KB article.
Based on "Grading the Results" part we identified problem with 2 of 4 values - open/delete
Where we are getting avg. results around 2,2 millions nanoseconds (as bad are values more than 150k for Open and more than 300k for Delete).
But it's still not that weird thing. I'm getting those bad values, but customer not(also when tried log in as me). So we don't have any idea why is this happening.