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.
Depends on your workload, I have measured (back at Centera) a
significant win for mixed read/write as well (at least 20%) depending on
file size.
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.
Won't ever happen, no one wants to lose 50% of their performance :-)
ric
--
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
