Synology DSM: An Increase in Drive Bad-Sector Count

Symptoms and applicable DSM versions

The stored article concerns DSM 6.2–7.2. It describes a nonzero bad-sector count or an email/DSM notification such as “bad sector count increased.” Bad sectors can develop over time and may exist even on a new drive; a stable count calls for continued monitoring, not an unconditional guarantee of health.

For DSM 7.2.1 or later, use the drive status shown in Storage Manager > HDD/SSD and the current vendor guidance to decide whether replacement is needed.

Inspect the history

1. Open Storage Manager > HDD/SSD.
2. Select the suspect drive.
3. Open Health Info > History > Drive Key Information, using the equivalent label in the installed DSM version.
4. Inspect the Bad Sector Count graph.

Also check the warning emails and DSM desktop notifications. If the count stays stable, continue monitoring and maintaining backups. A rapidly increasing count may precede failure; if DSM reports the drive as Critical, follow the replacement guidance.

Data scrubbing

The source recommends running data scrubbing twice a year. Use it only on a supported pool/filesystem configuration and schedule it for the actual workload. It checks supported data/parity consistency; it is not a replacement for backups, a universal repair of physical bad sectors or a guarantee against data loss.

DSM data-scrubbing guide.

Replace a failing drive

Check the Synology compatibility list for the NAS model and replacement drive. Identify the exact physical drive before removal; consult the drive-identification guide and the model’s hot-swap/shutdown requirements.

RAID types without data protection

1. Back up all data.
2. Shut down the NAS.
3. Remove and replace the failed drive.
4. Start the NAS. For a single-bay model, install DSM as required.
5. Create a new storage pool and volume.
6. Restore the backed-up data to the new storage.

RAID types with data protection

• If an unused suitable drive is available and DSM is version 7, use the documented Replace Drive feature where supported.
• If no unused drive is available, or the system uses a version earlier than DSM 7, replace failed drives one at a time and repair the storage pool after each replacement: DSM 7 / DSM 6.2. Confirm that repair has completed and the pool remains recoverable before removing another drive.

Matching official English article. Its public page may require JavaScript. This stored translation preserves the source’s version-specific flow and qualifies its stable-count and scrubbing claims.

Original case/reference: stored source.