Bug 834172
| Summary: | Conservative merge for meta-data split-brain | ||
|---|---|---|---|
| Product: | [Community] GlusterFS | Reporter: | Pranith Kumar K <pkarampu> |
| Component: | replicate | Assignee: | Pranith Kumar K <pkarampu> |
| Status: | CLOSED EOL | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | pre-release | CC: | bugs, gluster-bugs, jdarcy, vbellur |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | FutureFeature | ||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2015-10-22 15:40:20 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Kind of an enhancement request, which would normally be low severity, but this seems like a pretty important thing to add. pre-release version is ambiguous and about to be removed as a choice. If you believe this is still a bug, please change the status back to NEW and choose the appropriate, applicable version for it. |
Description of problem: Avati, What should be the behavior when there is metadata split-brain?. While we are doing mostly the right thing in terms of detecting a syntactic conflict in meta data (and calling it "split brain"), we are doing nothing at all in terms of merging/resolving conflicts. Unlike data, there are more interesting possibilities with POSIX metadata w.r.t semantic merge/resolution. The entire problem boils down to basically two attributes - permission and ownership. Rest of the attributes are either non-modifiable as "meta data" (st_blocks, st_ctime etc.) or we don't care (e.g st_atime). We can provide a few merge policy options if we detect meta data conflict, like - "apply the most conservative permission", "apply most conservative permission ignoring the execute bit", "change ownership to owner of parent directory", "change ownership to root". At the very least we need to support a very basic semantic merge - if copies are accidentally identical, consider the conflict resolved. And this needs to be done for both meta data and data (and possibly extended to GFID mismatch as well) Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: