menfor.blogg.se - Sector is clear not clear

The benefit of keeping the database in stable storage is that it allows the reporting of unreadable sectors to be persistent, as it will survive reboots, volume reconfigurations, and firmware upgrades (provided the upgrade is to a code that supports USM), volume state changes, and volume transfers. Unique Volume Identifier (not the SSID).It is recorded using volume centric information, which includes: The unreadable sector database is maintained in stable storage and contains an entry for each unreadable sector detected. How does the unreadable sector database work and what is logged to it? An unreadable sector is unrecoverable and the data contained in that location should be considered lost and must be recovered by some other means. However, there is no attempt made by the controller firmware to emulate capabilities for disks that do not natively support them.įor the purposes of this article, an 'unreadable sector' is defined as a volume logical block address (LBA) that is considered completely unreadable due to a physical disk media related double fault condition OR a physical disk media related single fault condition on non-redundant volumes (RAID 0). Persist media error conditions through RAID reconfiguration operations (DVE, DCE).īecause NetApp supports both FC-SCSI and SATA disks in a single subsystem, the feature is designed in a way that does not rely on physical disk functionality and is handled completely in the controller firmware.Successful completion of writes to optimal RAID 5 volumes even when parity cannot be generated.All continuation of reconstructions and other long-running operations despite media errors.Persist reporting of unreadable sectors.

Better reporting of the unreadable sector (and USM related conditions) in the Major Event Log (MEL).

The five main functional improvements provided by USM are:

The feature is designed to be mostly transparent to the end-user and therefore no configurable options are available and the functionality cannot be disabled. The Unreadable Sector Management (USM) feature provides a controller-based method for handling unreadable sectors that are detected during normal I/O processing, and long-running operations such as reconstructions.