NAS arrays are devices that store and share data over a network. They are widely used in businesses and homes for backup, file sharing, and media streaming. However, the reliability of NAS arrays can be compromised due to bad sectors on drives, resulting in data loss or corruption. To prevent this, it is important to improve the reliability of NAS arrays by performing regular self-tests and RAID scrubbing.


Self-tests are diagnostic checks that monitor the health and performance of the NAS array and its components. They can detect potential problems such as bad sectors, electrical issues, and mechanical issues.

RAID Scrubbing

RAID scrubbing is a process that verifies the integrity and consistency of the data stored on the NAS array. It compares the data blocks across different disks and repairs any discrepancies or errors. RAID scrubbing can also recover data from a failed disk if the NAS array is configured with redundancy.

However, RAID Scrubbing alone may not be enough to fix all the bad sectors in some cases. For example, if there is a Command Timeout (CTO) error, RAID Scrubbing would simply find the location of the CTO error, read the data that is supposed to be there from redundant RAID data, and write the data to the bad sector. Because the bad sector is detected by a CTO, no pending reallocation mark is set, and data written to the bad sector will still be bad. If multiple bad sectors are targeted by a single command, only the first bad sector is marked as pending reallocation, and the remaining bad sectors are not marked. RAID Scrubbing will not be marking them as pending reallocation and therefore will not fix them properly.

Tips to Boost your NAS Array Reliability
  1. Run self-tests regularly so that you can identify and fix issues before they affect your data.
  2. Schedule to run RAID scrubbing frequently to ensure that your data is always accurate and accessible.
  3. Perform a Self-Test with the Complete SMART Test option before running RAID Scrubbing. This way, all the bad sectors can be detected and repaired by using the redundant RAID data.

In a data dependent world, the ULINK DA Drive Analyzer AI algorithms disrupt drive failure prediction with 7-8 times more effectiveness than traditional systems.


QNAP and ULINK Release DA Drive Analyzer, AI-powered Drive Failure Prediction Tool for NAS 

 Photo Credit: yacobchuk


Latest Versions

DriveMaster Release

DriveMaster 9: v9.2.1800

Test Suite Release

ULINK NVMe Protocol: v6.0 (New)
ULINK NVMe Regression: v5.0 (New)

TCG Opal Family Certification: v6.0 (New)
TCG Opal Family SSC Multiple Namespaces Protocol Test Suite: v2.0
TCG Opal Family SSC Application Note: v5.5 (New)
TCG Enterprise Application Note: v5.0
ULINK TCG/I1667 Opal Family Protocol: v10.0 (New)
ULINK TCG Enterprise Protocol: v5.0

ULINK SATA/ATA Protocol: v9.0
ULINK SATA/ATA Regression: v9.0 (New)
SATA-IO Device Digital: v4.0
SATA-IO Host Digital: v3.0

ULINK SAS/SCSI Protocol: v4.5
ULINK SAS/SCSI Regression: v5.0 (New)

Test Reporter

v4.4.1 (New)