The primary purpose of implementing RAID (Redundant Array of Independent Disks) is to ensure data availability even in case of drive failure. In a redundant RAID setup, replacing a faulty drive with a new one allows the RAID array to be rebuilt. However, if an uncorrectable read error (UNC) occurs, the RAID typically cannot withstand the removal or failure of another drive. As a result, the Network Attached Storage (NAS) places the RAID in a degraded mode. What should you do in such cases? How can you prevent such situations?
Tips to Deal with RAID in Degraded Mode
If the NAS supports RAID, it can reconstruct data from the faulty sector using redundant information stored on other drives, allowing the system to continue using this reconstructed data. However, due to the presence of the UNC, the RAID enters a degraded mode. This indicates a reduced level of protection against data loss, particularly if other drives within the RAID experience catastrophic failures, such as being unable to spin up.
When the RAID is in a degraded mode, it is crucial for the user to take appropriate action to prevent further complications. The user should perform one of the following actions:
- Replace the drive with the UNC and rebuild the RAID.
- Perform a self-test with the drive containing the UNC, reinsert it, and rebuild the RAID.
- Or repair the UNC-causing bad sector through RAID Scrubbing. RAID Scrubbing involves scanning the RAID and repairing the bad sector responsible for the UNC error by utilizing data calculated from other drives in the RAID.
When the UNC-causing bad sector is successfully repaired, the drive will reallocate the sector to ensure proper functionality.
How to Prevent Degraded RAID Mode?
ULINK DA Drive Analyzer is a revolutionary tool that harnesses artificial intelligence to help organizations stay ahead of disk failures and optimize their RAID arrays for better reliability and performance. It gathers drive health data continuously for individual disks, monitoring critical parameters such as SMART (Self-Monitoring, Analysis, and Reporting Technology) attributes, and temperature. It uses machine learning algorithms to predict drive failures before they occur, allowing administrators to take pre-emptive action and prevent UNCs and RAID in degraded mode.
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QNAP Launches the AI-Powered DA Drive Analyzer 2.0 – Predicts NAS Drive Failure Within 24 Hours & Enhances Enterprise Privacy
Photo Credit: Vladimir_Timofeev
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