feat: decrease the reconnect delay of v2 volume nvme initiator

[derekbit]

Which issue(s) this PR fixes:

Issue longhorn/longhorn#9818

What this PR does / why we need it:

The current default value for --reconnect-delay is 10 seconds. We can reduce this value to 2 seconds.

• Advantages: Faster IO resumption post-upgrade
• Disadvantages: Increased frequency of retries

Special notes for your reviewer:

Additional documentation or context

[coderabbitai]

Walkthrough

The changes in this pull request involve modifying the defaultReconnectDelay constant in the pkg/nvme/nvmecli.go file from 10 seconds to 2 seconds. This adjustment affects the reconnect delay behavior within the connect function of the NVMe CLI. No new functions were introduced, and existing functionalities related to NVMe device management, including command execution and error handling, remain unchanged.

Changes

File	Change Summary
pkg/nvme/nvmecli.go	Updated defaultReconnectDelay constant from 10 to 2

Assessment against linked issues

Objective	Addressed	Explanation
Decrease the reconnect delay of v2 volume NVMe initiator (#9818)	✅

Possibly related PRs

• chore: update nvme-cli to v2.10.2 #159: The changes in this PR involve updating the nvme-cli tool, which is directly related to the functionality of the pkg/nvme/nvmecli.go file where the defaultReconnectDelay constant is modified, impacting the reconnect behavior of the NVMe CLI.

Suggested reviewers

• DamiaSan
• innobead

---

📜 Recent review details

Configuration used: .coderabbit.yaml
Review profile: CHILL

📥 Commits

Reviewing files that changed from the base of the PR and between a878ed0 and 9ef1e51.

📒 Files selected for processing (1)

• pkg/nvme/nvmecli.go (1 hunks)

🔇 Additional comments (1)

pkg/nvme/nvmecli.go (1)

22-22: LGTM with considerations for monitoring

The reduction of defaultReconnectDelay from 10s to 2s aligns with the goal of faster IO resumption after upgrades. While this change will improve recovery speed, it may lead to increased retry frequency.

Consider:

1. Adding monitoring/metrics for reconnection attempts to track the impact of this change
2. Adding a comment explaining the rationale for the 2-second value to help future maintainers understand the trade-off decision

Let's verify if there are any other timeouts or delays that might need adjustment to work harmoniously with this change:

✅ Verification successful

Based on the verification results, I can now generate the final response:

Verified: Reconnect delay change is safe and isolated

The change to defaultReconnectDelay is used solely as a parameter for the NVMe connect command and works in conjunction with other timeout parameters (ctrl-loss-tmo and keep-alive-tmo). The reduced delay of 2 seconds is a reasonable value that doesn't conflict with other timing configurations.

• The change is properly scoped to the NVMe connect command in pkg/nvme/nvmecli.go
• No other components or timeouts in the codebase depend on this value
• The value is passed directly to the NVMe CLI without any derived calculations

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Search for related timeout/delay configurations
rg -n '(timeout|delay|tmo).*=.*[0-9]+' --type go

# Search for any existing monitoring of reconnection attempts
rg -n '(reconnect|retry).*metrics?' --type go

Length of output: 694

---

Script:

#!/bin/bash
# Let's search for the usage of defaultReconnectDelay and any related connection parameters
ast-grep --pattern 'defaultReconnectDelay'

# Search for nvme connect command usage and parameters
rg -n 'nvme.*connect.*-.*delay' --type go -A 3 -B 3

# Search for any retry or reconnect logic
rg -n 'func.*(connect|reconnect)' --type go -A 5

Length of output: 34845

---

Script:

#!/bin/bash
# Let's search for any other timeout or delay configurations in the NVMe related code
rg -n '(timeout|delay).*=.*[0-9]+' pkg/nvme/ -A 2 -B 2

# Search for any comments or documentation about reconnection behavior
rg -n 'reconnect' pkg/nvme/ --type go -A 2 -B 2

Length of output: 415

---

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 22.89%. Comparing base (a878ed0) to head (9ef1e51).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #164   +/-   ##
=======================================
  Coverage   22.89%   22.89%           
=======================================
  Files          34       34           
  Lines        4813     4813           
=======================================
  Hits         1102     1102           
  Misses       3537     3537           
  Partials      174      174           

Flag	Coverage Δ
unittests	22.89% <ø> (ø)

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[DamiaSan]

It's ok for me, 2 is also the default value we have in go-spdk-helper for BdevNvmeAttachController.