Re: FUA and TCQ (was: Plan: journalling fixes for WAPBL)

[<Paul.Koning%dell.com@localhost>]

> On Sep 23, 2016, at 5:49 AM, Edgar Fuß <ef%math.uni-bonn.de@localhost> wrote:
> 
>> The whole point of tagged queueing is to let you *not* set [the write 
>> cache] bit in the mode pages and still get good performance.
> I don't get that. My understanding was that TCQ allowed the drive to re-order 
> commands within the bounds described by the tags. With the write cache 
> disabled, all write commands must hit stable storage before being reported 
> completed. So what's the point of tagging with cacheing disabled?

I'm not sure.  But I have the impression that in the real world tagging is rarely, if ever, used.

	paul