Sata 3 Gb/S; Time-Limited Error Recovery (Tler) - Western Digital WD1002FBYS Technical Reference Manual

Product Features
3.1

SATA 3 Gb/s

SATA 3 Gb/s is the next generation interface for SATA hard drives. It adds to the functionality
of the SATA I interface with the following features:
Native Command Queuing (NCQ) — server feature for performance in random I/O
transaction environments. It aggregates many small random data transfers and allows the
disk to reorder the commands in a sequential order for faster access.
Improved Power Management— provides improved power management features
including Host Initiated SATA Power Management (HIPM) and Device Initiated SATA
Power Management (DIPM).
Staggered Spin-up — allows the system to control whether the drive will spin up
immediately or wait until the interface is fully ready before spinning up.
Asynchronous Signal Recovery (ASR) — robustness feature that improves signal
recovery.
Enclosure Services — defines external enclosure management and support features.
Backplane Interconnect — defines how to lay out signal line traces in a backplane.
Auto-activate DMA — provides increased command efficiency through automated
activation of the DMA controller.
Device Configuration Overlay (DCO) — allows hiding of supported features via a
SATA feature mask.
3.2

Time-Limited Error Recovery (TLER)

WD has delivered coordinated error management in the form of Time Limited Error Recovery
(TLER). TLER-capable hard drives will perform the normal error recovery and, after 7 seconds,
issue an error message to the RAID controller and defer the error recovery task until a later
time. With coordinated error handling, the hard drive is not dropped from the RAID array,
thereby avoiding the entire RAID recovery, replacement, rebuild, and return experience.
The error handling is further coordinated between the TLER-capable hard drive and the RAID
card. The TLER capable drive will respond without waiting on the error to be resolved. RAID
cards are very capable of handling this with a combination of parity protection and journaling.
The RAID card flags the error in the error log and proceeds to deliver data using parity
protection until the drive retries its own error recovery and corrects the error. This is quite
similar to error management proven in SCSI-RAID for many years. Though TLER is designed
for RAID environments, it is fully compatible with and will not be detrimental when used in
non-RAID environments.
16 RELEASED 11/13/08 (WD CONFIDENTIAL)
WD RE3 XL333M
2679-701179-A01