Avi Kivity wrote:
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.
Different tests on different hardware
give different results at different times!
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.
We don't get to decide this, customers do.
As they say in the raid forum... fast, cheap, good - pick any 2
We just need to ensure we don't turn good into bad with fs mistakes.
jim
P.S. no flames because we chose no-battery == disable-write-cache
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
