Tejun Heo wrote:
For most SATA drives, disabling write back cache seems to take high toll on write throughput. :-(
I measured this yesterday. This is true for pure write workloads; for mixed read/write workloads the throughput decrease is negligible.
As long as the error status is sticky, it doesn't have to hold on to the data, it's not gonna be able to write it anyway. The drive has to hold onto the failure information only. Yeah, but fully agreed on that it's most likely dependent on the specific firmware. There isn't any requirement on how to handle write back failure in the ATA spec. It wouldn't be too surprising if there are some drives which happily report the old data after silent write failure followed by flush and power loss at the right timing.
I got flamed for this on another list, but let's disable the write cache and live with the performance drop.
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