Mark Lord wrote:
Jody McIntyre wrote:
We turn write caching off for data integrity reasons (write reordering
does bad things to journalling file systems if power is interrupted -
and at the scale of many Lustre deployments, it happens often enough to
be a concern.) I'm also concerned about the effects of NCQ in this area
so we'll probably turn it off anyway.
..
I haven't done a detailed examination lately, but..
Both write-caching and NCQ re-ordering should be safe on Linux.
The kernel will issue FLUSH_CACHE_EXT commands as required to checkpoint
data to the disk.
It depends on the fs's use of barriers (or not).
Without barriers, FLUSH CACHE[ EXT] isn't issued very often.
Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
