![]() ![]() Generally, Western Digital enterprise drives such as Raptor, Caviar RE2 and RE2-GP (RAID Edition) come with TLER Read "Enabled" (7 seconds) and TLER Write "Enabled" (7 seconds) while desktop drives such as Caviar SE, SE16, and GP come with TLER Read and Write Disabled (configured as 0 seconds, to disable). The array controller can then handle the data recovery for the limited amount involved, rather than marking the entire drive as faulty.Įffectively, TLER and similar features limit the performance of on-drive error handling, to allow hardware RAID controllers and software RAID implementations to handle the error if problematic. If the drive itself is inherently reliable but has some bad sectors, then TLER and similar features prevent a disk from being unnecessarily marked as 'failed' by limiting the time spent on correcting detected errors before advising the array controller of a failed operation. This is a long process, degrades performance, and if more drives fail under the resulting additional workload, it may be catastrophic. Hardware RAID controllers and software RAID implementations are designed to recognise a drive which does not respond within a few seconds, and mark it as unreliable, indicating that it should be withdrawn from use and the array rebuilt from parity data. The process for this can sometimes take several seconds or (under heavy usage) minutes, during which time the drive is unresponsive. Modern hard drives feature an ability to recover from some read/write errors by internally remapping sectors and performing other forms of self-test and recovery. ![]() ![]() In some cases, there is a conflict as to whether error handling should be undertaken by the hard drive or by the RAID implementation, which leads to drives being marked as unusable and significant performance degradation, when this could otherwise have been avoided. Limiting the recovery time allows for improved error handling in hardware or software RAID environments. In computing, error recovery control ( ERC) ( Western Digital: time-limited error recovery ( TLER), Samsung/ Hitachi: command completion time limit ( CCTL)) is a feature of hard disks which allow a system administrator to configure the amount of time a drive's firmware is allowed to spend recovering from a read or write error. JSTOR ( April 2010) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Error recovery control" – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification. ![]()
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