Time-limited error recovery
Time-Limited Error Recovery ( TLER ) German time-limited error correction , describes the time available to a hard drive to carry out an error correction. The term TLER is for Western Digital - hard drives used. Similar competitor technologies that fulfill the same function are called Error Recovery Control (ERC) at Seagate or Command Completion Time Limit (CCTL) at Samsung and Hitachi .
If a defective sector appears during write / read processes, a hard disk tries to solve the problem itself and to skip the defective sector. This process can take many seconds or minutes. If the hard disk is combined with other hard disks to form a RAID array, the RAID controller usually removes it from the array after eight seconds and marks it as defective if it has not been able to correct the error by then. The result is higher material costs and a less secure array. At this point, TLER intervenes: If the hard drive does not get the error under control within seven seconds (therefore “time-limited”), it “asks” the RAID controller for assistance in troubleshooting. This can prevent the hard drive from being ejected from the array too early.
The default values for the time-limited error correction for desktop hard drives and hard drives for server use therefore differ in the delivery state. Until recently, Western Digital offered a software called WDTLER.EXE for configuring this value as a download. This can no longer be found in the download area of the official website. However, the tool is still available for download on various other websites and in forums.