NAS-138129 / 26.04 / special vdev changes to catch up with ZFS 2.4

[william-gr]

• Relax vdev types for special/metadada vdev in pool creation
• Change special_small_block_size from checkboxes to select box (Inherit/On/Off)
• Add conditional validation only when "On" is selected (1 byte to 16 MiB)
• Fix inherit label formatting to show human-readable sizes (e.g., "128 KiB")
• Style customize link as text link positioned close to field
• Update pool creation helptext from "small block IO" to "blocks below configured size"
• Apply changes to both dataset and zvol forms

Testing:

Create a pool with a couple raidz special vdevs. Set special vdev attribute on dataset and zvol.

Downstream

Affects	Reasoning
Documentation	Special Vdev now allows all the types and new options in daatset/zvol edit
Testing

[bugclerk]

Jira URL: https://ixsystems.atlassian.net/browse/NAS-138129

[claude[bot]]

Claude finished @william-gr's task —— View job

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Code Review Complete! 🎉

Great work on implementing the special vdev enhancements for ZFS 2.4! The implementation is solid with well-structured code, comprehensive tests, and good architectural decisions. Here's my feedback:

✅ Positive Aspects

The PR demonstrates strong engineering practices with thorough test coverage (172 new test lines for dataset form, 163 for zvol form), proper use of shared utilities in dataset.utils.ts, and consistent implementation across both dataset and zvol forms. The validation logic is well thought out with conditional validators that activate only when needed.

🔍 Areas for Improvement

1. Modern Angular Pattern Violations (CLAUDE.md)

The codebase should follow modern Angular patterns per CLAUDE.md guidelines:

• @ngneat/until-destroy usage: Both other-options-section.component.ts:4 and zvol-form.component.ts:6 use @ngneat/until-destroy, but CLAUDE.md states: "RxJS Cleanup: Use takeUntilDestroyed(this.destroyRef) from @angular/core/rxjs-interop instead of @ngneat/until-destroy."

This is a codebase-wide pattern to migrate, so it's acceptable for this PR to maintain consistency with existing code. However, future work should move toward takeUntilDestroyed.

2. Template Expression Complexity

Both templates have complex inline expressions that hurt readability:

In other-options-section.component.html:135-156 and zvol-form.component.html:173-194:

form.value.special_small_block_size === OnOff.On

Consider extracting to component properties:

protected get isSpecialVdevEnabled(): boolean {
  return this.form.value.special_small_block_size === OnOff.On;
}

3. Accessibility Enhancement

The customize link buttons have good aria-labels, but the threshold input field could benefit from more context. Consider adding aria-describedby to connect the tooltip content more explicitly.

4. Minor Code Duplication

The logic for toggling showCustomizeSpecialSmallBlockSize and setting default values is duplicated between:

• other-options-section.component.ts:252-259
• zvol-form.component.ts:849-856

Consider extracting to a shared utility if this pattern appears elsewhere, though the current duplication is minimal and acceptable.

5. Test Coverage Gaps (Codecov: 75.38%)

Per Codecov, 32 lines are missing coverage, primarily in:

• zvol-form.component.ts: 25 missing lines (62.12% patch coverage)
• other-options-section.component.ts: 3 missing lines (93.33% patch coverage)

The zvol form could benefit from additional tests covering edge cases in the inheritance logic (lines 469-484) and encryption integration paths.

📝 Code Quality Notes

Good:

• ✅ Enum extraction properly implemented (OnOff.On instead of hardcoded strings) per reviewer feedback
• ✅ Validation only applies when OnOff.On is selected (lines 202-213 in other-options-section, 234-245 in zvol-form)
• ✅ Proper use of constants from dataset.constants.ts for thresholds
• ✅ Human-readable size formatting with buildNormalizedFileSize()
• ✅ Consistent payload transformation via shared transformSpecialSmallBlockSizeForPayload utility
• ✅ SCSS mixin reuse with customize-link-button for consistent styling

Architecture: The separation between UI state (special_small_block_size + special_small_block_size_custom) and API payload is well-designed. The transformSpecialSmallBlockSizeForPayload function in dataset.utils.ts:114-136 elegantly handles the mapping.

🎯 Summary

This is a well-executed PR that successfully implements the ZFS 2.4 special vdev requirements with proper validation, thorough testing, and consistent UX across forms. The code is maintainable and follows most project conventions. The main suggestion is to align with modern Angular patterns (particularly takeUntilDestroyed) in future iterations, though maintaining consistency with existing code is reasonable for this PR.

[codecov[bot]]

Codecov Report

:x: Patch coverage is 76.11940% with 32 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 86.28%. Comparing base (fae8433) to head (b67743e). :warning: Report is 5 commits behind head on master. :white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...tasets/components/zvol-form/zvol-form.component.ts	63.23%	25 Missing :warning:
...options-section/other-options-section.component.ts	93.47%	3 Missing :warning:
...data-wizard-step/metadata-wizard-step.component.ts	40.00%	3 Missing :warning:
src/app/pages/datasets/utils/dataset.utils.ts	91.66%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #12719      +/-   ##
==========================================
- Coverage   86.29%   86.28%   -0.02%     
==========================================
  Files        1826     1825       -1     
  Lines       67746    67908     +162     
  Branches     8176     8219      +43     
==========================================
+ Hits        58463    58593     +130     
- Misses       9283     9315      +32     

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[bugclerk]

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