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NinjaOne Backup — Error 311: Integrity Check Failed

Audience: T2 Use when: Backup fails with "Error 311: INTEGRITY_CHECK_TOO_MANY_ERRORS_FAILED."

What This Error Means

NinjaOne performs periodic integrity checks on the backup repository stored on the NAS. Error 311 means the integrity check found too many inconsistent or missing files within the repository — exceeding the threshold where the repository can be considered reliable.

This is different from a backup job failure — it means the backup data that's already stored on the NAS may be partially corrupt or incomplete.

Why Integrity Checks Fail

Cause Explanation
NAS drive failure or degradation Files written to the NAS were corrupt at the hardware level
NAS filesystem errors The NAS filesystem (ext4, Btrfs, etc.) has errors affecting backup repository files
Abrupt backup interruption A power loss or crash mid-write left repository files in an inconsistent state
NAS storage full during a write Files were partially written when the drive hit capacity
Repository corruption from a previous error A prior Error 342 (write error) or 306 (snapshot deleted) left orphaned data

Step 1 — Check NAS Drive Health First

Before attempting any repository repair, confirm the NAS storage is healthy:

  1. Log into NAS admin panel (Synology DSM or QNAP QTS)
  2. Synology: Storage Manager → HDD/SSD → check SMART for all drives; check storage pool health
  3. QNAP: Storage & Snapshots → check disk health and RAID status
  4. Confirm no drives are degraded, failed, or showing reallocated sectors

If the NAS drive is failing: replacing the drive takes priority over fixing the backup repository. A corrupt repository on a failing drive will re-corrupt.

Step 2 — Check NAS Free Space

# From the protected device
Get-ChildItem "\\NAS-HOSTNAME\backups\ninjaone" -ErrorAction Stop |
Measure-Object -Sum Length | Select @{N='TotalGB';E={[math]::Round($_.Sum/1GB,1)}}

Also check NAS admin panel for free space on the backup volume. If it's critically low, address space first (empty recycle bin, delete decommissioned device folders).

Step 3 — Delete and Rebuild the Repository

If the NAS hardware is healthy and Error 311 persists: the cleanest fix is to delete the corrupt repository and let NinjaOne run a fresh full backup.

⚠ This means losing all existing local revisions for that device. Cloud revisions are unaffected. Discuss with T3 or Nate before doing this on a server.

To delete the local repository:

  1. NinjaOne → device → Backup → Manage → Image Backup Plan → Delete Local Backup Data
  2. Confirm deletion
  3. Trigger a new backup run — NinjaOne will perform a fresh full local backup (takes hours for large systems)

Step 4 — If Cloud Data Is Also Affected

Error 311 typically affects only the local NAS repository. Cloud data is stored separately in AWS. If cloud integrity is also suspect: escalate to NinjaOne Support — they have backend tools to assess cloud repository health.

Escalate to NinjaOne Support If:

  • Error 311 recurs after deleting and rebuilding the local repository
  • Cloud revisions also appear inconsistent or missing
  • NAS hardware is healthy but integrity failures continue
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