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6e338f Anonymous 2026-04-21 11:16:04
Raid disk migration
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# Migration Process and Incident Analysis
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1. Objective of migration
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The goal was to:
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Replace existing RAID storage with larger disks
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Preserve all media data and permissions
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Minimize downtime for Jellyfin media services
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2. Migration approach
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Step 1 — New RAID creation
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Two new disks were configured in PERC as RAID1
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The system exposed them as /dev/sdd
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Step 2 — Filesystem creation
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A GPT partition table was created
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ext4 filesystem was applied to the new volume
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Step 3 — Initial data transfer
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Data was copied using:
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rsync -aHAX --numeric-ids --progress
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From:
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/mnt/Media
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To:
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/mnt/newMedia
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3. Secondary migration
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A separate dataset was migrated:
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/mnt/BonusDisk/JellyfinMedia/Motorvakantie 2024
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→ /mnt/Media/JellyfinMedia/Motorvakantie 2024
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This was done using rsync with preservation flags to maintain:
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Ownership
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Permissions
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ACLs
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Extended attributes
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4. Issue encountered during migration
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Symptom
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Two MP4 files became unreadable after migration.
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Observed error
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moov atom not found
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Invalid data found when processing input
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5. Investigation outcome
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Key findings
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Files existed in both source and destination
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File sizes were consistent in some cases
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ffprobe failed on both copies
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Original playback still worked in media players
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Root cause
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The issue was not filesystem corruption but:
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MP4 container metadata inconsistency
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Likely incomplete or non-finalized file state during copy
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rsync faithfully copied an already problematic file state
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6. Technical explanation
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MP4 files rely on a moov atom containing index metadata.
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Possible scenarios:
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moov located at end of file (camera-style encoding)
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file copied during incomplete write/finalization
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metadata not properly finalized before transfer
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This causes:
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ffprobe failure
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but partial playback may still succeed in tolerant players
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7. Resolution approach
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For affected files:
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Attempt container rebuild using ffmpeg:
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ffmpeg -i input.mp4 -c copy -movflags +faststart output.mp4
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If unsuccessful:
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re-copy from true original source
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or re-ingest from camera/archive
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8. Lessons learned
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1. Rsync preserves problems
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Rsync does not validate media integrity; it replicates file state exactly.
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2. Media must be “finalized” before migration
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Files actively written or not fully closed can copy as corrupted artifacts.
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3. Verification requires more than size checks
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Tools like ffprobe or checksum validation are required for media integrity
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4. Two-pass rsync is essential for live systems
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Initial sync during operation
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Final sync after stopping writes
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9. Best-practice migration workflow (refined)
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Create destination RAID and filesystem
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Perform initial rsync pass
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Stop all write processes
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Perform final rsync pass
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Validate with:
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rsync --dry-run
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media probing (ffprobe)
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Switch mounts via UUID in /etc/fstab
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Monitor system before removing old storage