While a drive is in operation, the head may come across a sector with a weakened magnetic read level. HDD Role Grown Defects (G-list) HDD Level This is common in HyperFlex (HX)/ Virtual Storage Area Network (VSAN) environments. If disks are in Just a Bunch Of Disk (JBOD), the OS will see errors as they are not corrected by the controller.If the OS has the required context to correctly resolve the medium error, it should be handled by the OS.This notification is no longer just an advisory message that would inform the system that the event has occurred, it is a request for the OS to act because the HDD and RAID controller was not able to recover from the medium error.If the HDD reports a medium error and the RAID controller cannot handle the recovery, then the host will be notified of the error.When does the Operating System (OS) see medium errors? In some cases, the controller will not be able to handle the medium error and will pass the error to the host to handle the error.Based on the RAID configuration, the controller may be able to handle the medium error reported by the HDD and no further action will be required.
The RAID controller will encounter medium errors while Patrol Reads, Consistency Checks, Normal Reads, Rebuilds, and Read / Modify / Write operations.How does the Raid controller detect medium errors? If all the recovery steps fail the drive will generate a 03/11/0x error back to the host and the LBA(s) will be placed on the pending defect list.
#Raid monitor proccess code#
When the HDD is unable to retrieve data that was written it invokes the HDD recovery code which will try various error recovery steps to successfully read the data from the media. The HDD tries to read from the media and for some reason is unable to retrieve the data that was written. Step 1.The HDD periodically performs Background Media Scans to detect errors. How does the HDD detect the medium error? Poor error map function in HDD manufacture that results in padding the current primary defect locations.Transient conditions caused by temporary shock, vibration, or acoustic events that result in off-track writes.Transient conditions, high fly writes caused by soft particles.Sometimes recoverable with multiple retries. Unreliable Logical Bus Address (LBA) read location.The most common cause of medium errors is poor signal amplitude that results in Note: Medium errors are also referred to as media errors Handle HDD Medium Errors The document also outlines the Hard Disk Drive's (HDD) and Redundant Array of Independent Disks (RAID) controller's role when you identify medium errors on the drives. If your network is live, make sure that you understand the potential impact of any command. All of the devices used in this document started with a cleared (default) configuration.
The information in this document was created from the devices in a specific lab environment. The information in this document is based on hard disks in Unified Computing System (UCS). There are no specific requirements for this document.
#Raid monitor proccess how to#
This document describes different types of disk errors, how to classify them, and tools you can use to identify them.
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